Glossary Archives - The Absolute Sound https://www.theabsolutesound.com/category/audiopedia/glossary/ High-performance Audio and Music Reviews Mon, 10 Feb 2025 15:36:52 +0000 en-US hourly 1 https://wordpress.org/?v=6.8.2 Glossary: Sound Quality (SQ) https://www.theabsolutesound.com/articles/hi-fi-audio-glossary-sound-quality-sq/ Thu, 15 Aug 2024 22:36:15 +0000 https://www.theabsolutesound.com/?post_type=articles&p=56424 Over recent years, our online guides have created an extensive […]

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Over recent years, our online guides have created an extensive encyclopedia of audio terminology. We decided to bring these disparate dictionaries of audio terms together for the first time. This exhaustive guide is the result.

While the days of trying to baffle people with terms only the cognoscenti know are (hopefully) behind us – many readers might recall the patronizing salesman in the ‘Grammo-phone’ sketch from Not The Nine O’clock News in the early 1980s – this is still a terminology-led industry, and knowing the terms is a good idea if we are to be able to recognize how components might conceivably be different, and why.

While it’s important not to get too hung up on the terminology – we are in an industry where observed performance should always remain more important than specifications – knowing the difference between a ported loudspeaker and a sealed-box loudspeaker is important and knowing that a sealed-box loudspeaker and an infinite baffle design are basically one and the same is important, too.

 

SOUND QUALITY (SQ) TERMS

 

Accuracy

A problematic concept taken literally, but sometimes meant to indicate believability. See Realism, Believability, and the absolute sound.

Bass

Lower musical frequencies, from approximately 20 Hz to 200 Hz.

Believability

When we judge audio equipment we are fundamentally asking if the rendition of sound is “believable” in the sense that real instruments in a real performance space might sound like this. Believability integrates the instrumental and vocal sounds captured, along with the effects and mixing and mastering processing applied to the recording. See also: the absolute sound.

Black Background

By ‘black background’ we generally mean the myriad elements of noise and distortion that mask or blur the rendition of small signals (e.g. reflections in a concert venue or harmonics from an instrument). So, when a speaker or DAC or amplifier is introduced into a reference system and resolution or ambience or inter-transient silence or depth of image or soundspace rendition are increased, these phenomena can fall under the ‘black background’ term.

Bright

Refers to an elevated level of treble, generally somewhere in the range between 4 kHz and 10 kHz. See Frequency Balance.

Definition

See Resolution

Dynamics

The ability of the device we are discussing to produce soft and loud sounds without distortion. Dynamics are affected by timing: when a device doesn’t respond to an input as quickly as the input requires, the transition from soft to loud or back can be delayed leading to a “heavy” or “slow” or “soft” sound. Well executing dynamic timing leads to terms like “punch”, “drive”, “quickness”, and “pace”.

Frequency

Musical instruments and voices produce sound by vibrating (strings, instrument bodies, vocal chords, oscillators, horns, drum skins, etc). These vibrations can be characterized by their frequencies. Frequencies are measured in terms of cycles per second or Hz (1 Hertz is 1 cycle per second). A “low” frequency would be for example the low string (E1) of a bass guitar, which is 41 Hz. A “middle” frequency would be A4 on a piano keyboard, which is 440 Hz. A “high” frequency would be the top note of a piccolo, C8, which is 4186 Hz. An important thing to understand when using instrumental examples is that all acoustic instruments and voices vibrate (resonate) at the fundamental frequencies mentioned above and at multiples of the fundamental. So, a piano will resonate at 440 Hz (fundamental) when A4 is played and at 880 Hz (second harmonic) and 1320 Hz (third harmonic) and 1760 Hz (fourth harmonic) and so on. So, the sound of real instruments extends well above their highest fundamental tone. See: Bass, Midrange, Treble.

Frequency Response

When discussing sound quality, we often mention a set of terms related to frequency response. Frequency response is the output level of the device (speaker, amp, DAC, etc) for each relevant frequency (generally 20 Hz to 20 kHz, but possibly higher). A signal of constant level is fed into the device at each frequency, and we measure the output. Since the input is level with frequency, we generally want the output to be level with frequency or “flat”. But there can be cases where we do not want exactly flat response, particularly with speakers where on-axis and off-axis measurements may differ and, e.g., flat on-axis response may not sound accurate.

Frequency Balance (overall)

We often characterize the frequency response of a device using the term frequency balance. When we are speaking about overall balance, we usually mean the basic shape of the frequency response curve: is it tilted up in the treble or up in the bass or scooped (depressed) in the middle or rolled off in bass and treble?

Frequency Balance (octave to octave)

We may discuss frequency balance in octave-to-octave terms. Octaves are just a doubling of frequency. So the octave above 41 Hz extends to 82 Hz, and the octave above 440 Hz extends to 880 Hz. Octave-to-octave frequency balance is a useful way to communicate if local regions of frequency response are smooth and even or bumpy or peaky. The smoother an octave and the next one are, the more instruments in that range sound right, because the fundamentals and harmonics are in balance. It helps to understand the the harmonic character of an instrument is how we know a guitar from a cello or a piano from a clarinet.

Midrange

Middle frequencies of musical instruments and voices, generally from approximately 300 Hz to 3000 Hz.

Noise Level

This term usually does not refer to audible noise in the sense of noise you hear explicitly as you would with wind noise in a car. Rather, reviewers and audiophiles estimate the very low-level noise of audio devices by observing how the device affects small signals (instrumental overtones or venue reflections). Sometimes a low noise level is referred to as a “black background”.

PRaT (Pace, Rhythm and Timing)

While it is easy to think of musical sounds in what is called the “frequency domain”, meaning in terms of the musical notes with their frequencies (e.g. A4 on piano has a fundamental of 440 Hz), we also need to think of the output of audio equipment in terms of time. Almost all audio equipment has some amount of time distortion, meaning that certain tones that should have occurred at time t=X will completely or partially occur at t=X+.01 seconds or t=X+.2 seconds. This timing error leads to observational terms like “blur” and “overhang” and “slowness” and “softness”. As a way of summarizing how well a device limits time error, some reviewers use the term PRaT (Pace, Rhythm, and Timing) to capture the accuracy or lack thereof in the time dimension.

Realism

The idea that reproduced music sounds, or does not sound, as it would when performed. A difficult concept because of the listener’s generally limited knowledge of the original performance environment, and the heavy use of studio techniques in which the music is not performed in a real space at one time. See: Believability.

Resolution

By visual analogy, resolution is the ability of a device to produce separate aural images of closely spaced objects (could be closely spaced in location or in time). A high resolution sound field has clarity, depth, and little blur. We perceive resolution as definition of sounds.

Soundstage

The reason for having stereo (2 channel) or potentially even more channels is to present the music as occurring in a 3-dimensional space. Soundstage refers to the 3-dimensional presentation of performers, primarily in the left-right and front-back elements of their positioning on a virtual stage. We often refer also to the overall dimensions of the virtual stage that is presented, articulating whether it is wide or narrow and shallow or deep.

Soundspace

This term refers to the sense that an audio device gives of the size and shape of the overall space in which the virtual performers appear. Remember that the instruments and voices resonate to make sounds. These sounds travel out from the instruments and if the performance were in a large concert hall, the reflections would occur perhaps 1 or 2 seconds after the initial sound from the instrument made its way to your ears. The time delay of the reflections is used by your ear/brain to sense the size and shape of the concert hall. If the performance were in a small club, the reflections would occur more quickly and your ear/brain would sense the smaller venue.

the absolute sound

This term refers to the sound of real instruments and voices played in a real space. The idea of the absolute sound is to create a reference or a standard for observationally objective evaluation of the sound of audio equipment. If the sound of audio equipment believably resembles the absolute sound, we judge that it is performing well. If the sound does not believably resemble the absolute sound, then we judge that it is performing poorly. Since nothing is perfect, these evaluations must necessarily comprehend the tradeoffs that all real audio equipment make. Listeners can learn what the absolute sound means by attending concerts, especially those involving acoustic or limited-amplification instruments and voices. Without such a reference communication between listeners is rendered limited if not impossible. See: Believability.

Tilt

See Frequency Balance.

Transparency

Transparency is used to indicate the sense that a device can transmit a signal faithfully. In music reproduction, this means the device gets closer to what we imagine happened at the live (studio or concert) event. Transparency is mostly a combination of resolution and naturalness. We add the naturalness criterion because at times, practically speaking, there are some artificial distortions that can seem to enhance resolution at the price of naturalness.

Treble

Upper frequencies of instruments and voices, generally from approximately 4000 Hz to 20,000 Hz or higher.

Warm

Refers to somewhat elevated mid-bass and lower midrange, generally somewhere in the range from 80 Hz to 400 Hz.

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Glossary: Speakers https://www.theabsolutesound.com/articles/hi-fi-audio-glossary-speakers/ Mon, 12 Aug 2024 20:41:58 +0000 https://www.theabsolutesound.com/?post_type=articles&p=56362 Over recent years, our online guides have created an extensive […]

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Over recent years, our online guides have created an extensive encyclopedia of audio terminology. We decided to bring these disparate dictionaries of audio terms together for the first time. This exhaustive guide is the result.

While the days of trying to baffle people with terms only the cognoscenti know are (hopefully) behind us – many readers might recall the patronizing salesman in the ‘Grammo-phone’ sketch from Not The Nine O’clock News in the early 1980s – this is still a terminology-led industry, and knowing the terms is a good idea if we are to be able to recognize how components might conceivably be different, and why.

While it’s important not to get too hung up on the terminology – we are in an industry where observed performance should always remain more important than specifications – knowing the difference between a ported loudspeaker and a sealed-box loudspeaker is important and knowing that a sealed-box loudspeaker and an infinite baffle design are basically one and the same is important, too.

 

LOUDSPEAKER TERMS

The world of high-performance loudspeakers has cultivated a language all its own to describe not only the various configurations and types of speaker and drive units, but also their performance characteristics.

 

Active

Loudspeaker systems that contain or partner dedicated electronics – power amplification plus electronic crossovers and equalizers, some of which can be entirely in the digital domain.

Bandwidth

The range of frequencies with defined upper and lower limits over which a system operates.

Bass

Lower part of the audible frequency range. Can be subdivided into deep bass (below 40Hz), midbass (40Hz–100Hz), and upper bass (100Hz–250Hz).

Baffle

The front face of a loudspeaker. Its role is to hold the loudspeaker drivers securely, while preventing the sound emanating from the front of the loudspeaker interacting with any emanating from the rear.

Bracing

The inside of a loudspeaker cabinet can flex and resonate, adding its own colorations. Judicious and careful use of cabinet bracing can help stiffen the cabinet and reduce unwanted distortions.

Brilliance

Alternative terminology for the highest audible frequencies from 6kHz–12kHz.

Co-Axial

Literally ‘symmetrical about a common core’, as in shielded aerial cable or loudspeaker drive units (such as those made by KEF or Tannoy).

Coloration

A general term used to describe the audible effects of a whole range of different distortions in different hi-fi components, but especially record decks and loudspeakers.

Crossover

More precisely described as a dividing network, the electrical circuitry inside a loudspeaker, which apportions the drive signal to the individual drive units.

Decibel (dB)

A logarithmic unit used to express relative loudness.

Distortion

Literally any deviation from the original, though often specified to particular mechanisms. Also known as ‘nonlinearities’.

Drive Unit or Driver

The sources of acoustic output in a loudspeaker; includes woofers, tweeters, and so on.

Dynamic Drivers

Loudspeaker drivers that create compressions and rarefactions in air by means of a pistonic drive unit operating at audio frequencies. These are typically cone-shaped for drivers operating in the bass and lower midrange, and dome-shaped for upper midrange and high frequency drivers.

Dynamic Range

The ratio (dBs) between the loudest and softest sounds a system or component can handle.

Electrostatic

A principle employed in some exotic loudspeaker and headphone transducers, whereby a large sheet of thin material (typically Mylar) is induced to vibrate (at audio frequencies) across its whole area by an electrostatic charge.

Enclosure (a.k.a. Cabinet)

The rigid mounting for the loudspeaker drive units, often also containing the crossover network, and – in some active loudspeaker systems – even the amplifiers. In most cases, the term is self-explanatory (the enclosure encloses the drivers, crossover, etc.), but can also notionally be applied to the frame housing planar magnetic or electrostatic panels.

Filter

An electrical circuit used to limit the bandwidth of a signal, and one of the principle properties required of a crossover.

Frequency Range/Spectrum

Can refer to any spread of frequencies, but most commonly the Audio Band of human hearing, from 20 cycles per second (20Hz) in the extreme bass to 20,000 cycles per second (20kHz) in the highest treble.

Frequency Response

The variation in output across a specified range of different frequencies.

 

Harmonic

Harmonics are the whole number multiples of a base frequency called a fundamental.

Harmonic Distortion (Thd)

The addition of unwanted harmonics to a signal.

 

HF

High frequency (i.e., treble). Often used in terms of describing loudspeaker drive units (‘HF’ directly equating to ‘tweeter’).

Horn

As the name suggests, a design using an acoustic horn – often with a specialized compression drive unit – to increase the efficiency of the loudspeaker system. This is one of the earliest examples of loudspeaker technology, as the basic concept predates electrical loudspeaker driver design.

Hz (Hertz)

Unit of frequency of vibration, 1Hz = 1 cycle per second.

Impedance

Measure of the electrical resistance (and reactance) of a component’s inputs and outputs.

Infinite Baffle (a.k.a Sealed Box)

In theory, the sides and rear of a loudspeaker cabinet act as extensions of the front baffle in trying to keep rear-radiation from the loudspeaker drivers at bay. When the cabinet is fully sealed, preventing any rear-radiating sound in the process, it is considered an infinite baffle.

kHz

1000Hz or vibrations per second (1kHz actually corresponds to a tone nearly two octaves above middle C).

LF

Low frequency (i.e., bass). Often used in terms of describing loudspeaker drive units (‘LF’ directly equating to ‘woofer’).

Materials

Materials science has caught up with the world of loudspeakers in all three places, but especially in enclosure material (which can often be aluminum, carbon-fiber, or one of a wealth of mineral-filled resins) and drive unit materials (which can be also be made from aluminum or carbon-fiber, but also ceramic, industrial diamond, beryllium, a number of different plastics, as well as composites conjoined by lightweight foam.

Midband or Midrange

The middle range of audio frequencies, where the ear is most sensitive. Can be subdivided into lower midrange (250Hz–500Hz), midranges (500Hz–1kHz), and upper midranges (1kHz– 2kHz).

Monitor

High quality (usually standmount) loudspeaker.

Moving Coil

A transducer system that changes mechanical energy into electrical energy or vice versa, used in high quality pickup cartridges and in conventional loudspeaker drive units.

Noise

Random unwanted low-level signals.

Octave

Span of frequency or pitch that represents a doubling or halving of frequency.

Ohm

Unit of electrical impedance or resistance.

Port

In reflex loaded loudspeakers, the opening which is ‘tuned’ to the box size and main driver characteristics to improve output at low frequencies.

Presence

Alternative terminology for the high frequencies between 4kHz–6kHz.

Reflection

Higher frequencies can be very directional, and their output can easily ‘bounce’ off reflective walls and ceilings, interfering with the sound directly from the tweeter itself. Room acoustics experts recommend placing absorption at the ‘first reflection points’ either side of the loudspeaker to limit this interference.

Resonance

A physical property where one vibrating system causes another system to ‘sympathetically’ vibrate at specific frequencies. These resonances can happen inside the loudspeaker cabinet, along the walls of the cabinet.

Sensitivity

The amount of output (loudness, expressed in decibels) for a given electrical input (usually 1 watt).

Separation

The separateness of the left and right channels of a stereo audio system.

Signal-To-Noise, S/N

The difference between maximum level of a signal and the background noise left when the signal is removed.

Snake Oil

A term used by consumers to describe products that involve technological principles that are not well understood by the consumer. Examples of such technologies include EMI, decimation mathematics, image creation in the brain, bandwidth of the ear, phase effects, pre-ringing and reference measurement parameters. Snake Oil is a term of approbation which strongly implies that what is not understood is not valuable, rather than focusing value judgements on results achieved.

Stereo

Literally ‘solid’ – a system which uses two loudspeakers (or a pair of headphones) to create solid spatial sonic images.

Subsonic

Below the audible frequency range, commonly considered to be anything below 20Hz.

Top Octave

Very high frequencies in the 10kHz–20kHz region.

Treble

Upper part of the audible frequency range. Can be subdivided into lower treble (2kHz–3.5kHz), treble (3.5kHz–6kHz), and upper treble (6kHz– 10kHz). Also see Presence and Brilliance.

Transmission Line

Instead of a conventional sealed or ported enclosure, a transmission line takes the sound generated from the back of the bass speaker through a long and labyrinthine damped pathway within the speaker enclosure itself.

Tweeter

Small loudspeaker drive unit used for higher frequency (treble) sounds. Commonly a pistonic dome design but can be anything from a planar magnetic or folded ribbon of metal foil to the corona discharge of high-energy electrical plasma. As this last can produce hazardous levels of nitrogen oxides and ozone in a living room, plasma tweeters are relatively rare!

Ultrasonic

Frequencies above the notional limits of audibility, but still considered important in high-resolution audio systems. Typically, in the region from 20kHz–100kHz.

Watt

Unit of electrical power (the product of voltage and current).

Woofer

Loudspeaker drive unit that handles lower frequency (bass) sounds.

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Glossary: Digital https://www.theabsolutesound.com/articles/hi-fi-audio-glossary-digital/ Mon, 12 Aug 2024 20:36:20 +0000 https://www.theabsolutesound.com/?post_type=articles&p=56360 Over recent years, our online guides have created an extensive […]

The post Glossary: Digital appeared first on The Absolute Sound.

]]>

Over recent years, our online guides have created an extensive encyclopedia of audio terminology. We decided to bring these disparate dictionaries of audio terms together for the first time. This exhaustive guide is the result.

While the days of trying to baffle people with terms only the cognoscenti know are (hopefully) behind us – many readers might recall the patronizing salesman in the ‘Grammo-phone’ sketch from Not The Nine O’clock News in the early 1980s – this is still a terminology-led industry, and knowing the terms is a good idea if we are to be able to recognize how components might conceivably be different, and why.

While it’s important not to get too hung up on the terminology – we are in an industry where observed performance should always remain more important than specifications – knowing the difference between a ported loudspeaker and a sealed-box loudspeaker is important and knowing that a sealed-box loudspeaker and an infinite baffle design are basically one and the same is important, too.

 

DIGITAL AUDIO TERMS

Perhaps no single category in all of high‑end audio has spawned a more convoluted ‘alphabet soup’ of technical terms and abbreviations than digital audio. Indeed, the topic has given rise to so many TLAs (three-letter acronyms) that at times it seems almost impossible to keep them straight in one’s mind. We present here a minimalist glossary that, while by no means exhaustive, covers at least a few of the more common acronyms and terms you are apt to encounter when you go shopping for digital audio components.

 

AAC

This acronym stands for ‘Advanced Audio Coding’, which is one of several coding standards for lossy digital audio compression (see ‘Compression’ in this glossary for more details). AAC was originally developed as the successor of MP3, which is another form of lossy compression. AAC is generally thought to deliver somewhat better sound quality than MP3 for any given bit rate.

AAC comes up often in product specifications sheets because it is the default audio format for such popular products and services as: YouTube, iPhone, iPod, iPad, iTunes, and the Sony PlayStation 3.

ADC

The acronym ADC (sometimes also shown as ‘A/D’) is shorthand for ‘Analogue-to-Digital Converter’. Realistically, not many audiophiles own, or would have any reason to own ADCs, but it is worth bearing in mind that recording studios and production houses use ADCs in order to create the digital audio music files that most of us enjoy.

ADCs receive analogue audio signals, sample those signals at very high frequencies (under the control of extremely accurate clocks) and then generate digital bit-streams (that is, multi-bit words of digital audio data) that represent the sampled analogue audio signals as accurately as possible. As with any other type of audio equipment, ADCs are not created equal, and some have audibly superior performance capabilities to others.

AIFF

This acronym stands for ‘Audio Interchange File Format’, which is a digital audio file format developed by Apple. AIFF stores audio data in uncompressed pulse-code modulation (PCM) format and is therefore lossless. Because they are both uncompressed and lossless, AIFF files require more data storage space than compressed audio files would do, but the trade off—one that many audiophiles happily embrace—is that AIFF introduces no sonically deleterious ‘compression artefacts’ of any kind.

ALAC (and ALE)

The acronym ALAC stands for ‘Apple Lossless Audio Codec’, which is sometimes alternatively called ALE (for ‘Apple Lossless Encoding’). In short, ALAC is a method for compressing digital audio data in a completely lossless manner (meaning all of the original audio data is preserved).

ALAC was initially a proprietary Apple standard, but as of 2011 Apple made the codec available as open source and royalty free software. Both iTunes and iOS devices support ALAC (whereas Apple systems and devices typically do not support other lossless standards), so that ALAC has become the de facto lossless compression standard for audiophiles who use Apple computers and/or iOS devices.

Note that AIFF and ALAC are not the same things. AIFF digital audio data is not compressed at all and therefore is inherently lossless; ALAC digital audio data is compressed but can be decoded for playback in a lossless manner. ALAC digital audio files are roughly one half the size of equivalent uncompressed files.

Bit

One unit of digital data, typically represented by voltages either above or below a clear-cut threshold and by convention held to represent a ‘1’ or a ‘0’ as used in binary numbers. Typically abbreviated as a lower-case ‘b’ – as in, “My DAC can handle PCM digital audio files at resolutions up to 32-bit/384kHz.”

Bit-rate

The speed, expressed in number of bits per second, at which digital audio data is processed or transferred from one device to another or playback. For example, one of the better sounding and more popular forms of MP3 transfers data at 320kbps (kilobits per second).

Byte

An 8-bit ‘word’ of digital data, abbreviated with a capital ‘B’ – as in, “I store my digital music library on a 2TB drive” (where 2TB means ‘2 Terabyte’). The digital word lengths used in digital audio are typically multiples of 8-bits: hence, 16-bit, 24-bit, or 32-bit words are frequently discussed.

CD

The acronym stands for ‘Compact Disc’, a physical storage format for digital audio commercially launched in the early 1980s by Philips and Sony. CDs are polycarbonate discs that incorporate a highly reflective metallic layer upon which ‘pits’ can be etched along with shiny spaces in between the pits, known as ‘lands’. The pits and lands effectively represent the ‘1s’ and ‘0s’ inherent in digital audio data.

By convention, CD standards are set forth in the so-called Red Book, which calls for the digital audio data to be stored in 16-bit words of data sampled at a rate of 44.1 kHz. When writers talk about ‘CD resolution’ digital audio files, they will often refer to them as ‘16/44.1’ files. While CDs are arguably the most popular digital audio format on the planet, other storage formats are now on the rise, many of them offering resolutions (and, in principle, sound quality) much higher than that of CDs.

“The ear is extraordinarily sensitive to timing and thus can readily differentiate between clock errors.”

Clock

Digital clocks are extremely important in digital audio, both when encoding and decoding or playing back digital audio files. Since clocks govern the precise time intervals at which digital audio files are captured, and then later played back, it is critically important for clocks to be stable and accurate so that the intervals between clock beats are maintained with extreme precision.

The human ear is remarkably sensitive to clock timing errors, so that errors occurring down at the picosecond lever are thought to be audible. The more accurate, stable, and precise a clock is, the better the sound of the component will be (all other things being equal). Some very high-end components use extremely exotic Rubidium (or ‘atomic’) clocks to achieve the ‘nth’ degree of sound quality.

Codec

A codec is a software or firmware program that can encode or decode a digital audio stream. The term ‘codec’ represents a condensation of the more cumbersome phrase ‘encoder decoder’. Some popular codecs you may have heard of include MP3, MP4, ALAC, FLAC, Ogg Vorbis, and many more.

Compression

Compression is a data manipulation process where digital audio files are condensed in order to conserve data storage space. It is useful to think of compression, as it applies to digital audio, as a two-part process. First, digital audio files are compressed to reduce them to a more compact and manageable size for storage; then, later on, the compressed files are decoded or de-compressed for playback. There are many types of audio compression algorithms, but they generally fall into two categories: lossy compression and lossless compression.

Lossy compression algorithms do the most efficient job of compressing data, but with the tradeoff that—when it comes time to decode the lossy files—only part of the original digital audio data is restored, while some is irretrievably lost (hence the name ‘lossy’). Two of the more popular lossy compression codecs are AAC and MP3.

Lossless compression algorithms are less efficient than lossy algorithms in terms of conserving storage space, but they have the benefit that—when it comes time to decode the files—fully 100% of the original digital audio data is restored. Most audiophiles perceive lossless compression to offer audible performance benefits vs. lossy compression (although there is some debate on this topic).

As broadband internet speeds continue to increase and very high-capacity storage devices have become less expensive and more commonly available (even in small, portable, handheld devices) there is less pressure on audiophiles to conserve storage space, so that over time lossless compression algorithms have become increasingly popular. Two of the more popular lossless compression codecs are ALAC and FLAC.

DAC

This acronym stands for ‘Digital-to-Analogue Converter’, with the DAC serving as an essential ingredient in any digital audio playback device. In simple terms, the job of the DAC is to receive digital audio data at extremely precisely clocked intervals and to convert that data into an analogue output that mirrors (or is proportionate to) the numerical values of the digital audio data received.

DACs can be, and often are, condensed to fit on single integrated circuit chips, with popular DAC makers including firms such as Burr-Brown, ESS, Texas Instruments, Wolfson, and many more. However, it is possible to create DACs from individual, discrete parts—an approach some audio component manufacturers have pursued in the interest of superior sound quality.

Either way, it is important to understand that the DAC devices used in a given component do not necessarily define or determine the component’s characteristic sound (other circuit elements also play a major role in determining sound quality).

DSD

The acronym stands for ‘Direct Stream Digital’, which is a digital audio encoding and decoding system developed by Philips and Sony as the format of choice for use in their higher-than-CD-resolution Super Audio CD discs (commonly called SACDs).

Unlike, PCM (pulse code modulation) formats, which store digital audio data in the form of 16-bit, 24-bit, or even 32-bit words sampled or clocked at rates ranging from 44.1 to 384 kHz, DSD is a single-bit, delta sigma modulated encoding process, but with extremely high sampling rates of 2.8224 MHz (known as DSD64) or 5.6448 MHz (known as DSD128). In principle, DSD files are extremely easy to decode for analogue playback, requiring only a basic low-pass filter. Some critics argue that DSD files have high frequency noise issues to contend with and that the delta sigma process has some inherent errors that are difficult to overcome. Proponents of DSD, however, argue the DSD achieves a smooth, free-flowing, analogue-like sound that is often difficult for PCM to achieve.

While SACD discs have never achieved the popularity of conventional Red Book CDs, their underlying DSD file format has won widespread popularity in recent years, since many music lovers now prefer listening to files downloaded or streamed from the Internet (or a local network). DSD files can be streamed or downloaded via a transfer process called ‘DoP’, which stands for ‘DSD over PCM’. This process does not convert DSD files to PCM format, but rather temporarily stores DSD data in PCM ‘data containers’ in order to simplify file transfers.

DSP

The acronym stands for ‘Digital Signal Processing’, a topic that comes up often in discussion of digital audio. One of the beauties of digital audio is the fact that, once analogue signals are converted into digital formats, they can be processed in ways that would be difficult if not impossible to achieve solely through analogue means. For example, DSP can be used to implement complex digital filtering systems that can shape the sonic character of the ultimate playback presentation in extremely subtle and potentially desirable ways. Likewise, DSP makes possible certain elaborate equalization (EQ) systems that would be very difficult to execute with a purely analogue EQ system. Finally, DSP allows designers greater control over various sonic variables including noise, transient response, resolution, etc. as well as greater control over various processing/ playback artefacts.

Dynamic Range

In audio, dynamic range is the difference between the smallest and the largest usable signal that can be passed through a transmission or playback system; this difference is expressed as a ratio and typically is quoted in dB (decibels). The human ear is said to have about 140dB of dynamic range (which is also, in rough terms, about the same dynamic range as some of today’s best microphones).

Since digital audio inherently involves creating digital representations of analogue sound waves, one question that arises is this: “Does the digital system have more or less dynamic range than the analogue signals it is attempting to represent?” All other things being equal, digital components with greater dynamic range often offer superior sound, in part because they do not lose low-level signals in noise, nor do they overload on very high-level signals.

Part of today’s emphasis on higher-than-CD-resolution digital audio files involves the fact that 24-bit files offer dramatically higher dynamic range than do the 16-bit files found in CDs.

FLAC

The acronym stands for ‘Free Lossless Audio Codec’. FLAC is one of the most popular and widely supported lossless audio codecs in use today, in part because it is an open-source, royalty-free software package, but also because FLAC readily supports metadata tagging, complete with storage of album cover art and the like.

Jitter

As mentioned under ‘Clocks’, above, timing is absolutely crucial in digital audio with particular emphasis on maintaining absolutely identical time intervals between clock pulses. Unfortunately, nothing is perfect so that small variations or errors between intervals can and do occur—errors called ‘jitter’, which will usually be quoted as worst case timing variations (for example: ‘Jitter: </= 9 picoseconds’).

As mentioned elsewhere in this glossary, the ear is extraordinarily sensitive to timing and thus can readily differentiate between clock errors, even when those errors are measured in the parts per million vs. clocks with errors measured in the parts per billion. The point is that all other things being equal, the digital playback system with the lowest jitter almost invariably sounds best.

kbps and Mbps

The former acronym stands for ‘kilobits per second’ and the latter for ‘megabits per second’; both terms are used to express data transfer speeds. ‘kbps’ figures often come up in discussion of lossy compression codecs as a means of comparing the net amount of audio data one codec can supply vs. another codec (typically, the higher the data rate, the better the lossy codec’s sonic performance will be).

You might, for example, see digital downloads offered in two types of lossy formats: ‘MP3 (CBR at 128 kbps) or MP3 (VBR at 320kbps)’—where CBR stands for ‘constant bit rate’ and VBR is short for ‘variable bit rate’. In this case, the MP3 128kbps digital audio file would take up less storage space, but the MP3 320kbps digital audio file would offer markedly superior sound quality.

One small tip: In talking or reading about acronyms like these bear in mind that a lower case ‘b’ denotes ‘bits’, while a capital ‘B’ denotes ‘Bytes’.

Metadata

Literally ‘beyond data’, metadata is information about the data itself. For example, in an audio file, this might mean the title track, the artist, the composer, the genre, date of recording, date of composition, the album cover, band members, and more. This information about the music is generally ‘embedded’ within the file itself, to be read and displayed by media players and music servers alike. Metadata is enormously useful for listeners, simply because ‘Good Vibrations’ is a more memorable file name than ‘a156e03c’ to humans. Older file formats (such as WAV) are less robust in preserving metadata than their more modern counterparts.

MP3

MP3 is one of the oldest and most widely supported lossy digital audio compression codecs in the world. Over time MP3, which was created by the Fraunhofer Institute in the early 1990s, has emerged as a free ISO (International Organization for Standardization) standard that has also been incorporated by the MPEG (Motion Picture Experts Group) as part of both the MPEG-1 and MPEG-2 Audio Layer III standard.

MP3 was instrumental in the explosive growth that personal digital audio devices have enjoyed over the last 15 years or so, because it offered a means of substantially compressing large digital audio files so that even fairly large music libraries could be condensed to fit in devices with limited storage capacity (for example, early generation iPods).

MP3 also served, for many listeners, as an introduction to ‘perceptual coding’, where the general idea is to reduce the amount of data used to represent aspects of sound thought to be beyond the perceptual resolution of most listeners, while devoting data to the aspects of sound most readily heard and perceived. The concept was to reduce dramatically the amount of data that needed to be stored while still appearing to deliver full fidelity sound for most listeners, most of the time. Naturally, the idea of throwing out potentially useful sonic data did not sit well with most audiophiles and has been a topic of controversy and heated debate ever since.

Networked Audio & Network Streaming

Music stored on a computer can be removed to devices distributed across a home network (more accurately, a LAN or Local Area Network). This typically involves storing music on a computer or network attached storage device, which also runs some form of music server program to store and order these music files. The music itself is played through a ‘media renderer’ in your audio system that is also attached to the same computer network.

Functionally similar to internet streaming, networked audio distributes your own music library within the local network, instead of relying on online providers to stream their own music. While the popularity of personal libraries stored locally looks set to wane as online services proliferate, the networked audio system is a great way to store all your existing music collection in one easily accessible place.

PCM (and LPCM)

The former acronym stands for ‘pulse-code modulation’, while the latter stands for ‘linear pulse-code modulation’; both are means of representing analogue audio signals in a digital format. Many audiophiles use the terms PCM and LPCM interchangeably, though in fact the terms do not mean the same thing. PCM/LPCM is by far the most popular digital audio encoding format in use today.

Both PCM and LPCM sample the amplitude of analogue signals at precise and identical timing intervals. When each sample is taken, the amplitude of the signal is quantized and recorded as a multi-bit digital word. The difference between PCM and LPCM involves the manner in which signal amplitude is quantized; in PCM, samples are quantized to the nearest value within a range of possible digital steps, whereas in LPCM, samples are quantized to steps that are uniform in level.

The quality of PCM and LPCM encoding is largely controlled by two factors: the sampling rate (that is, the rate at which samples are taken) and the bit-depth of the samples taken (that is, the length in bits of the digital words used to represent each sample). As a general rule, all other things being equal, higher sampling rates and greater bit depths equate to better sound quality. Thus, a 24-bit/384kHz file of a song would likely sound superior to a 16-bit/44.1kHz file of the same song, assuming the master recording captured high levels of sonic detail and nuance in the first place.

“All other things being equal, higher sampling rates and greater bit depths equate to better sound quality.”

Resolution

In simple terms, ‘Resolution’ is the catchall phrase most audiophiles use to describe the amount of digital audio data used to represent analogue audio signals. As a general rule, the less data used the lower the resolution (and sound quality) will be, while the greater the amount of data used the greater the resolution (and sound quality) will be—up to a level where a perceived ‘point of diminishing returns’ is reached.

Generally speaking, lossy compression codecs yield what are considered low-resolution digital audio files. CD files, captured at 16-bits/44.1kHz are considered the standard, and files with higher-than-CD bit-depths and/ or sampling rates are considered to be high-resolution files.

Can listeners hear the difference? In a word, yes. The only area where there is room for discussion involves the question, ‘When is high resolution high enough?’

Servers

This term is the shortened form of the term ‘music server’. Typically, music servers provide a means of storing large quantities of digital audio files along with user interfaces that facilitate loading, organizing, and playing digital audio files. As a general rule, servers are typically thought to be self-contained units that not only store digital audio files, but also can deliver them for playback on demand.

Snake Oil

A term used by consumers to describe products that involve technological principles that are not well understood by the consumer. Examples of such technologies include EMI, decimation mathematics, image creation in the brain, bandwidth of the ear, phase effects, pre-ringing and reference measurement parameters. Snake Oil is a term of approbation which strongly implies that what is not understood is not valuable, rather than focusing value judgements on results achieved.

Streamers

By definition, streamers are network-attached devices that may offer Ethernet, Wi-Fi, and/or Bluetooth connectivity, or any combination of the above. The primary purpose of the streamer is to allow digital files from a music streaming service (e.g. Qobuz, Tidal, Spotify, Apple Music etc) to be located, selected and converted from internet protocol format to a format readable by an audio device like a digital-to-audio converter (DAC). Streamers are usually connected to the internet via an RJ 45 connector on an Ethernet cable connected to a switch or router that is part of your home network (hard wiring limits droputs and allows hi-resolution signals, unlike Bluetooth). DACs usually accept USB, S/PDIF, AES/EBU, I2S or Optical inputs.  Streamers may or may not have storage of their own for local files (in which case they would properly be called ‘streamer/servers’). Streamers often have an input or inputs to accept external files, for example on a memory stick or a portable SSD. Streamers have user interfaces to allow their owners to view, choose, and play audio content from the available network resources at hand. The compatibility of streamers with various user interface applications (e.g. Tidal Connect or Roon) and the provision of interfaces for switching between services (e.g. BluSound OS allows choosing between 25 services and selection of multiple output devices) is a point of differentiation between streamers.

UPnP/DLNA

UPnP (Universal Plug and Play) and DLNA (Digital Living Network Alliance) are similar sets of interoperability guidelines, allowing digital media devices to work together with little or no need for complex ‘handshaking’ protocols. Devices that fall under one (or more usually, both) standards are designed to be compatible with one another as standard, and fall into three broad categories for audio systems: control point (which might be an app on a tablet), media renderer (the network-attached DAC or streamer), and media server (that might be a computer or NAS drive).

WMA

This acronym stands for ‘Windows Media Audio’ a family of audio data compression codecs developed by Microsoft that together are part of the Windows Media framework or ‘ecosystem’. The are four WMA codecs:

  • The original WMA codec is a lossy compression algorithm comparable to MP3.
  • The WMA PRO codec supports multichannel or surround sound files (with up to eight discrete channels) and supports ‘high resolution audio’ (at up to 24-bit/96kHz levels).
  • The WMA Lossless codec is a lossless compression algorithm.
  • The WMA Voice codec is a low bit-rate, lossy compression algorithm focused specifically on conversational voice content.

WAV (or WAVE)

This acronym stands for ‘Waveform Audio File Format’, which was developed by Microsoft and IBM, and which is an uncompressed and therefore lossless file format that typically uses LPCM encoding. In theory, WAV supports compressed audio as well, though this is rarely seen in actual practice.

WAV and AIFF files are compatible with Windows, Macintosh, and Linux operating systems.

In simple terms, WAV—much like AIFF—is all about preserving maximum sound quality while eliminating compression artefacts of any kind. Two drawbacks are that WAV files take up considerably more storage space than files encoded by lossless compression codecs and that WAV files do not lend themselves to storage of album/song-related metadata. Recognizing the sonic potential of WAV, many manufacturers of ripping and/or music server software have come up with workarounds to allow WAV files to be stored with associated metadata.

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Glossary: Analog https://www.theabsolutesound.com/articles/hi-fi-audio-glossary-analog/ Mon, 12 Aug 2024 20:31:05 +0000 https://www.theabsolutesound.com/?post_type=articles&p=56357 Over recent years, our online guides have created an extensive […]

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Over recent years, our online guides have created an extensive encyclopedia of audio terminology. We decided to bring these disparate dictionaries of audio terms together for the first time. This exhaustive guide is the result.

While the days of trying to baffle people with terms only the cognoscenti know are (hopefully) behind us – many readers might recall the patronizing salesman in the ‘Grammo-phone’ sketch from Not The Nine O’clock News in the early 1980s – this is still a terminology-led industry, and knowing the terms is a good idea if we are to be able to recognize how components might conceivably be different, and why.

While it’s important not to get too hung up on the terminology – we are in an industry where observed performance should always remain more important than specifications – knowing the difference between a ported loudspeaker and a sealed-box loudspeaker is important and knowing that a sealed-box loudspeaker and an infinite baffle design are basically one and the same is important, too.

 

ANALOG AUDIO TERMS

This brief section is intended for those who have little or no experience with analog audio and are eager to learn the basics. Treat this information as a set of foundational building blocks you can build upon later on.

 

JUST THE (ANALOG) BASICS

 

LPs, Records, ‘Vinyl’, or ‘Vinyls’

The whole idea behind analog audio is to achieve musically satisfying playback of vinyl phonograph records. Records are sometimes also called LPs (for ‘long play records’) or called ‘vinyl’ by the older generation or ‘vinyls’ by the younger buyers (as in, “I picked up some great new vinyls at the record shop today”). Vinyl LP records are relatively thin, flat vinyl discs, almost exactly 12-inches in diameter, with music—captured in the form of undulating grooves—pressed into their front and back sides. Traditionally, LPs rotate at 33 ⅓ RPM, although an increasing number of audiophile pressings now include multiple 45 RPM records, treating the LP as if it were a collection of 12” singles. In contrast, the single has commonly spun at 45 RPM and was often sold as either a 7” or 12” record. A small number of 10” extended play (‘EP’) records have also been produced, but – like the single – are rarely pressed today. By convention, the spiraling grooves in the record surface start at the outer rim of the record and move inward toward the record’s center. When the last piece of music on the record side is complete, the groove—no longer containing music—spirals inwards a bit further to a so-called ‘run-out groove’ where the stylus of the phonograph cartridge quietly rests, waiting to be lifted from the groove when the listener is ready either to turn the record over or to shut off the playback system.

Critically Important LP/Record Factoids

Staying within the (Straight) Lines: Masters lacquers for vinyl records are made on record cutting lathes where the lathe’s cutting head travels in a straight line from the outer rim toward the center of the master disc. In an ideal world, we would want the styli of our phono cartridges to follow this exact same straight line during playback, so that the phono cartridge/ stylus would remain perfectly tangent to the record grooves at all times. In practice, though, it is rarely possible to achieve true straight-line motion or perfect stylus-to-record-groove tangency at all times, so that engineers must create compromise solutions that position the phono cartridge stylus so that it remains nearly tangent to the record groove, most of the time.

Spacing Out: The spacing between record grooves is not constant, as some suppose. If you think about it, quieter musical passages require only very low amplitude modulations in the record grove, whereas loud and dynamic passages require groove modulations so high in amplitude that they are sometimes visible to the naked eye! Given this, record-cutting lathes can vary groove-to-groove spacing to allow for the dynamic swings that inevitably occur in music. This means that as the tonearm, phono cartridge, and stylus play the record from the outer edge to the innermost groove, their lateral motion is not absolutely constant, but rather varies in response to groove spacing variations.

Record Players

Some listeners (especially newcomers) sometimes use the informal term ‘Record Player’ to describe a complete record playback system, including a turntable, tonearm, and phono cartridge. However, audiophiles almost always discuss these playback components individually, as each has a separate role to play.

Turntables

Turntables are the devices we use to play or ‘spin’ vinyl records. The turntable’s job is to both support and rotate the record at a precise speed (typically either 33 ⅓ RPM or 45 RPM) during playback, while contributing as little noise and as few speed fluctuations as possible. (The human ear is extremely sensitive to speed fluctuations, because they translate directly into musical pitch fluctuations.) Some people use the word “turntable” to mean the whole record player assembly, but most serious audiophiles use the term to refer only to that part of the record player that is responsible for spinning the record.

Phono Cartridges

Phono cartridges are the devices tasked with ‘reading’ or tracking the grooves in the spinning record and then converting the physical movements involved in tracking the grooves into electrical signals that can be amplified for playback in our hi-fi systems. Phono cartridges have three basic elements: a stylus, a cantilever, and a motor (or signal generator mechanism) of some type. The stylus is the part of the cartridge that makes physical contact with the record groove and tracks the undulations in the grooves. Styli (the plural of stylus) are almost invariably made of extremely small, precisely shaped, and finely polished diamonds. The cantilever is a miniature rod or tube that forms a connection between the stylus and whatever type of electrical signal generator or motor the cartridge happens to use. The cantilever is typically supported by a flexible suspension system that serves double duty as both a ‘spring’ that supports the cartridge and as a damper to help control the motion of the stylus/cantilever mechanism. The motor of the phone cartridge translates the movements of the stylus in the record groove into an electrical signal that is analogous and proportional to the music encoded in the record grooves.

Tonearms

The tonearm’s job is to position the cartridge over the surface of the record and to hold the cartridge in place while the stylus is tracking the record grooves. This description sounds straightforward enough until you consider that the tonearm’s design brief can at times seem like a contradiction in terms.

For example, we want the tonearm to hold the cartridge’s body (or outer shell) almost perfectly still as the stylus, cantilever, and signal generating mechanism rapidly move in response to the groove modulations in the record. But at the same time, the tonearm cannot and must not hold the cartridge body in a rigidly fixed position; on the contrary, the tonearm must allow the cartridge freedom of movement in both the vertical (up and down) and horizontal (left and right) axes. These degrees of freedom of movement are necessary for three reasons.

First, tonearms must allow the phono cartridge to move so as to stay centered directly above the inwardly spiraling record grooves. Second, tonearms must allow cartridges to deal with the fact that many records are at least slightly eccentric, meaning the inward spiral of the groove is not necessarily smooth and continuous. Sometimes, listeners encounter records that require the tonearm to swivel back and forth (from left to right) as the record rotates, even if only very slightly. Third, many records are at least slightly warped, meaning the tonearm must allow the cartridge to move up and down to maintain a stable position relative to the surface of the record—a surface that, when viewed from the side, may at times appear to be ‘bobbing’ up and down as the record rotates.

Stated simply, the mission of the tonearm is to hold the cartridge in a stable position relative to record groove, while at the same time allowing the cartridge freedom of movement where necessary.

MORE ADVANCED ANALOG TERMINOLOGY

 

Anti-Skating Systems/ Skating Forces

The majority of tonearms on the market today are pivoted, non-tangential designs and the geometry of such arms makes for a condition where the cartridge stylus tends to be pulled inward toward the center of the record. This inward pull is called skating, and its result is that there is more stylus pressure on one side of the record groove than the other.

Ideally, we would want equal pressure on both sides of the record groove and to achieve this result many tonearms feature so-called anti-skating mechanisms that apply a compensatory force that is intended to offset skating forces.

Note that skating forces can and do vary with the amount of tracking force applied to the stylus, and also vary from one stylus shape to another (because styli of different shapes may have more or less ‘drag’ within the record groove). For these and other reasons, setting anti-skating forces is not an exact science and in fact some manufacturers advise against applying any anti-skating forces at all. In any event, adjustments to anti-skating force should—as with everything else in high-end audio—be verified by ear.

Arm Lengths/Stylus-to-Pivot Lengths

Phono cartridges mounted in pivoted tonearms move in an arc over the record and by following an arc the cartridge/stylus can achieve true tangency to the record groove at two points per record side. But at all other points the cartridge/ stylus assembly will experience some degree of tracing error, meaning the stylus will be just slightly askew to the ideal tangent-to-the-groove position.

This is where tradeoffs come into play and tonearm length looms large as a design variable. Generally speaking, the greater the length of a pivoted tonearm the lower its geometric tracing error will be—provided other length-induced design tradeoffs can be properly managed. However, increasing tone arm length is not a panacea, because longer tonearms may have potential problems with structural rigidity, unwanted resonance, cumbersome size, and excess mass.

These days the most common tonearm length is in the range of 9-inches from the pivot point to the stylus—a length that offers a good set of compromises in terms of structural rigidity, relative freedom from resonance, manageable mass, ease of handling, and reasonable physical size. At the same time, designers and listeners recognize that longer tonearms can and do reduce tracing error (because their arc shaped travel paths more closely approximate the theoretically ideal straight lines). For this reason, the analog world has in the past several years seen a resurgence of interest in 10-inch and 12-inch tonearms, with at least one manufacturer offering a turntable fitted with a 14-inch tone arm!

Azimuth

Azimuth refers to the degree of left/right tilt of the phono cartridge stylus as it rests in the record groove, where the ideal is for the stylus to be positioned exactly vertically in the record groove as viewed from the front.

One tricky factor, however, is that there is no guarantee that the stylus is perfectly aligned relative to the phono cartridge body, meaning that technically correct azimuth alignment might in fact require the cartridge body to be tilted just slightly to the left or right.

Not all tonearms (and especially not many inexpensive tonearms) offer provisions for making azimuth adjustments, but many mid and upper-tier tonearms do. Many enthusiasts have discovered that a very useful and simple tool for setting azimuth is a device called the Fozgometer (named for the veteran audio designer Jim Fosgate), which can used in conjunction with a set of recommended test records to check, revise, and adjust azimuth settings. It is also possible to use a test record and an oscilloscope for precision adjustment of azimuth, although this requires a considerably higher degree of user expertise… and the purchase of a test record and an oscilloscope!

Are the benefits of proper azimuth alignment audible? In high-resolution systems they most certainly are, making for a heightened sense of focus, clarity, and freedom from mis tracking on complicated musical passages.

Cartridge Overhang & Alignment/ Cartridge Adjustment Protractors

As stated above, the theoretical ideal would be for the phono cartridge stylus to move across the record surface following the same straight-line path followed by the record cutting head when the original master lacquer for the record was made.

The majority of turntables are fitted with pivoted tonearms that cause the phono cartridge/ stylus to swing in an arc across the record, rather than following a true straight-line path. Since an arc can only intersect a straight line at two points, the stylus can only achieve perfect stylus-to-groove tangency at two points on the record, meaning it will be slightly out of tangency at all other points on the record. To achieve best results with pivoted arms, two adjustments are critical: cartridge overhang (the exact distance from the arm pivot to the stylus) and cartridge alignment (the left-to-right angle of the cartridge relative to the tonearm and the record).

To help users adjust these two variables, many manufacturers offer cartridge alignment protractors, which are designed to slip over the turntable spindle and to rest temporarily on the turntable platter. Protractors provide markings that show where the stylus should be positioned in terms of overhang (X marks the spot) and that show how the cartridge/stylus should be aligned.

To use such protractors, listeners first loosen the fixing screws for their cartridges, then gently and carefully move the cartridges fore and aft and from left to right, following a gradual trial-and-error process until the desired overhang and alignment positions are achieved. Once the cartridge is correctly positioned, the fixing screws can be tightened to lock the cartridge in its properly aligned position.

Note that so-called straight-line or tangential-tracking tonearms also require overhang and alignment adjustments, but with the important difference that, once properly adjusted, they maintain perfect stylus-to-groove tangency across the entire record surface.

Cartridge Suspension & Dampening Systems

As noted above, the stylus/cantilever/motor assemblies used in all phono cartridges require some sort of suspension system, which in most cases will also double as a dampening system or ‘shock absorber’ of sorts. Many designs use either an elastomer ring or suspension block for this purpose, and as you may surmise the exact dimensions and compositions of these suspension/dampening elements are critical to performance.

If the suspension of the cartridge is too stiff or over damped, compliance will be reduced, and resonance problems may be introduced. On the other hand, if the suspension is too soft or under damped, compliance will be too high, and other types of resonance problems may arise (not to mention the potential problems of increased fragility and possible cartridge collapse). For obvious reasons, then, the idea is to achieve a carefully judged blend of appropriate compliance levels and damping characteristics that best suit the intended playback application.

It is worth noting that, in some moving coil cartridges, designers sometimes add a supplementary suspension/damping ‘tie-wire’ at the rear of the cantilever assembly to provide additional support and resonance control.

Cartridge Types

Phono cartridges tend to be classified by the types of signal-generation systems or ‘motor’ mechanisms they employ.

Moving iron & moving magnet: Moving iron and moving magnet cartridges are conceptually similar. In both cases, either a small magnet (moving magnet) or small ferrous metal tip with adjacent stationary magnets (moving iron) is fitted to the cartridge cantilever and positioned near a set of stationary coils of wire. As the stylus tracks the groove, the magnet or ferrous metal tip (acting as an induced magnet) is set in motion and generates a voltage in the cartridge’s signal coils. In most but not all cases, moving magnet and moving iron cartridges are considered high output designs and therefore should be used with phono stages that have a standard gain, moving magnet (“MM”) phono input.

As a general rule, moving iron cartridges are thought to offer better transient response than moving magnet designs, because their ferrous metal tips are lower in mass than equivalently sized magnets.

Moving coil: As their name suggests, moving coil cartridges feature cantilevers typically fitted with tiny cruciform frames around which are wound coils of wire positioned near sets of stationary magnets. As the stylus tracks the groove, the cruciform frame and coils are set in motion (within a fixed magnetic field), thus generating an audio signal. In the majority of cases, moving coil cartridges are considered low or mid-level output designs and therefore should be used with phono stages that have a high(er) gain moving coil “MC” input.

As a general rule, moving coil cartridges are thought to offer superior transient speeds and higher levels of detail than moving iron/ magnet cartridges, because their moving coils of signal wire are considerably lower in mass than moving magnet or moving iron signal generators. However, this theoretically superior performance comes at a price.

Generally speaking, moving coil models are more complicated to build and more costly to make and to buy than moving magnet/iron equivalents. Some moving coil models are prone to high-frequency resonances, which means designers must pay extra attention to damping schemes to mitigate potential problems. Finally, moving coil models typically require more costly high-gain/low-noise phono stages. With all this said, however, the majority of today’s top-tier phono cartridges are moving coil designs.

Optical: Optical phono cartridges use an optoelectronic mechanism to modulate a voltage supplied from an external power supply/ equalization box. In typical optical designs, which at this point are comparatively rare, the cartridge cantilever is fitted with a tiny light-permeable screen. When the stylus moves in the record grooves, the screen moves in response. An LED illuminates the screen, while an opto-electronic photodiode sensor located behind the screen ‘reads’ the light (as modulated by the moving screen) to produce an output signal.

Two theoretical advantages of optical cartridges are that their moving mechanisms are very low in mass, making for excellent clarity and transient speed, and they can in principle be very low in noise. One potentially significant drawback, however, is that they must be used with their own companion power supply/equalization boxes, which also serve in lieu of traditional phono stages.

Strain Gauge: Strain gauge-type cartridges are based—you guessed it—on strain gauges, which are flexible materials whose resistance to current flow changes as the materials expand and contract. In a stereo strain gauge cartridge, the cantilever is connected to two such strain gauges, with the strain gauges typically serving as both the suspension for the cantilever/stylus assembly and as the signal modulation mechanism.

Like optical cartridges, strain gauges require an external power supply box, but interestingly they do not require traditional RIAA equalization; this is because—unlike moving magnet, iron, or coil designs—strain gauges are not velocity sensitive transducers (where the signal depends upon how fast the stylus is moving), but rather are displacement-sensitive transducers (where the signal depends upon how far the stylus moves).

Advantages of strain gauges include the fact that their moving mechanisms are very low in mass and that their stylus/cantilever assemblies are directly and mechanically connected to the strain gauges that modulate their output signals. Three possible drawbacks are that strain gauge cartridges are costly to manufacture and to buy, are thought to be comparatively fragile, and they require use of a dedicated external power supply box.

Counterweights

Moveable counterweights are used at the back ends of tonearms, primarily to balance the arms once phono cartridges are installed, but also—in some but not all designs—to apply tracking force on the stylus. Also, for some unipivot tonearms, counterweights are deliberately eccentric in shape, so that the weights not only can move fore and aft, but also can rotate side to side for purposes of making azimuth adjustments. Typically, counterweights are made of relatively dense materials such as brass or, in some instances, even tungsten.

Headshells

The headshell is that element of the tonearm to which the phono cartridge is affixed, and which traditionally would provide a finger lift, if one happens to be used on the tonearm in question. Headshells may range from ultra-minimalist on through to quite elaborate designs that, in some instances, provide within-the-headshell adjustments for azimuth and for stylus rake angle.

Headshell designs can either be fixed (that is, permanently attached to the tonearm wand or perhaps even fashioned as an integral part of the wand) or detachable—usually via a locking collar of some kind. Proponents of fixed headshells cite their potentially superior strength, rigidity, structural integrity, and freedom from resonance, where proponents of detachable headshells emphasize the fact that detachable headshells facilitate cartridge swapping (because users are free to mount spare cartridges in separate headshells, thus making it possible to switch cartridges with a minimum of set-up hassles).

Motors

A wide variety of motors can be found in turntables, but some of the more common types are AC synchronous motors (motors that are in essence locked to the frequency of the mains), low-noise DC motors, and so-called ‘Hall Effect’ direct-drive motors (where in essence, the platter serves double-duty as the ‘armature’ of the motor).

Each type of motor has its ardent proponents, and each can, if well executed, give sonically superb results. The main points to grasp are that motors need to drive their associated platters at precise, unvarying speeds with as little noise as possible and with virtually no tendency to show speed fluctuations (not even extremely minor ones) in the presence of large or small-scale dynamic variations in the music.

Platters, Sub-Platters, Main Bearings, & Spindles

Platters: Platters are the relatively heavy, disc-like elements upon which records rest and rotate while in play. Ideally, we would want platters to be perfectly flat, perfectly round, and to be fitted with spindles that are perfectly centered in the platter’s top surface (the spindle is a round vertical post used to center the record upon the platter). Further, we would want platters to offer sufficient mass that, once in rotation, they would have enough inertia to be able to resist speed fluctuations—even when playing records where timing accuracy is hyper-critical (e.g., certain piano passages) or where there are wild dynamic variances over time (think of Tchaikovsky’s classic 1812 Overture). Finally, we would want platters made of materials that offer good internal damping and provide a solid, neutral sounding support surface for the record. It is common to see platters made of machined aluminum, glass, brass, copper, composite materials or combinations of the above.

Sub-Platters: Depending on the design brief being followed, some turntable designs feature platters that rest upon smaller sub-platters to which the turntable drive mechanism is connected and to which the main bearing of the turntable is attached.

Main Bearings: Main bearings must support the weight of the platter while allowing it to rotate as smoothly and quietly as possible. It is important to bear in mind that any noise— even seemingly very low-level noise—from the main bearing can be passed upward through the platter and the record, to be picked up by the phono cartridge. For this reason, precision-made main bearings are an absolute must for optimal sonic results to be achieved. It takes a great deal of expertise to design and to manufacture top-class main bearings, but the effort pays huge dividends in terms of sound quality. Indeed, one of the biggest differences between good vs. great turntables lies in the quality of the main bearings used.

Some common main bearing types include shaft and bushing designs (with or without continuous recirculating oil baths and with or without inverted bearing shafts), shaft and ball designs, air bearings (where the weight of the platter is borne upon a cushion of pressurized air), and opposed magnet supported bearings, where sets of opposing magnets are used to partially ‘levitate’ the platter thus relieving physical pressure on the bearing assembly. Bearings can be made of hardened tool steel with or without jeweled contact surfaces or balls, sintered bronze, other exotic metal alloys, ceramics, composites, specialized plastics/ polymers, and other man-made materials.

Spindles: Spindles are precision-made circular posts, typically made of metal, which protrude from the top center surface of the platter. Spindles are made to an industry standard diameter and their primary purpose is to act as a centering-pin for records, when records are placed on the platter for playback (and yes, there is a corresponding, industry standard, spindle-sized hole in the center of all LP records). But one other purpose for the spindle is to provide a gripping surface to which optional record clamps, if any, may attach.

Plinths

Plinths are the externally visible housings or structural frames for turntables. In some designs, the plinth is essentially an outer shell to which various sub-frames or assembles (for example, motor mounts) are attached—or from which they are suspended.

In other designs, however, the plinth basically is the frame of the turntable, to which the turntable’s tonearm, main bearing/platter assembly, and in some cases even the drive mechanism or motor is attached.

Can plinths affect sound? Recent Hi-Fi+ reviews of aftermarket plinths for popular turntables such as the Linn LP12 suggest that plinths can have a surprising high level of impact on the turntable’s overall sonic presentation.

For this reason, it is important to respect plinths as significant elements of turntable design and not as an afterthought.

Record Clamps and Vacuum Hold-Down Systems

Many analog audio experts think that it is desirable to clamp records firmly to the platters upon which they rest during playback and for this reason a number of turntable makers and aftermarket accessory manufacturers offer specialized record clamps, which typically are attached via the platter’s spindle.

Others go even further, suggesting that, since many records are very slightly warped, it is desirable not only to clamp records at their centers, but also around their outer perimeters (so that the records will lie perfectly flat upon the platter’s top surface). Accordingly, a handful of manufacturers offer ring-shaped clamps, typically made of metal, which slip over the outer edges of the record and turntable platter, thus coupling the record firmly to the platter, flattening out any warps in the record surface as a result.

Finally, it is worth noting that not all analog experts are devotees of record clamps, mostly out of concern that clamps might put undue pressure on the platter main bearing while potentially creating unwanted stresses in the record surface.

One way of achieving the benefits of clamping systems, but without actually using clamps, is to build turntables that incorporate vacuum-powered record hold-down systems. Turntable manufacturers such as SOTA and TechDAS have done just this, with very good results. The only drawbacks to the vacuum hold-down approach involve complexity, costs, and the need to manage the noise produced by the requisite vacuum pumps.

RIAA (and other) phono EQ curves

A fact little known among laymen is that records as pressed do not have flat frequency response. On the contrary, during the record mastering process specific equalization curves are applied curves that reduce the amplitude of bass frequencies and boost high frequencies. The typical EQ curve used is called the RIAA curve, where the acronym stands for Recording Industry Association of America. There are also other phono EQ curves that provide similar functions, although they are far less common than the RIAA curve. Alternate phono EQ curves include those from CCIR/Teldec, Columbia, DMM, and Decca/EMI. Arguments continue to rage today as to whether record companies switched wholesale to the RIAA curve when stereo arrived in 1958, or whether recordings cut in the 1960s or later used the alternate EQs derived in the monophonic era.

Why is phono equalization necessary? The answer is that bass content, if cut into the record with flat frequency response, would require record groove modulations so extreme that it is doubtful that even the finest phono cartridges could properly track them. What is more, the modulations would be so large in amplitude that they would force unfeasibly wide spacing between record grooves, which would severely limit the amount of content that could be included on each record side. At the other end of the audio spectrum, high frequency material, if cut into the record with flat frequency response, would potentially be so low in amplitude that it might get masked by naturally occurring groove noise.

Thus, phono equalization, complete with boosted highs and trimmed-back low frequencies, is always applied during the record mastering process. However, in order to restore flat frequency response when playing vinyl records, inverse phono equalization is applied during the playback process via a specific type of preamplifier called a phono stage. All phono stages provide inverse RIAA equalization, but some of today’s more elaborate, upper tier phono stages may also provide six or more specialized phono EQ curves, as mentioned above.

Rumble

Rumble is a measure of the detectable noise generated by turntables as they rotate, so that you could think of rumble as being the turntable world’s equivalent of the signal-to-noise-ratio in conventional audio electronics. Rumble is typically quoted as a negative dB figure (for example, -64dB) where—as with signal-to-noise ratios—the higher the negative number of dB, the quieter the turntable will be.

As with audio electronics, lower rumble in turntables may not necessarily be perceived as ‘lower noise’ (although it is just that), but rather as ‘enhanced low-level detail’ in the music.

Snake Oil

A term used by consumers to describe products that involve technological principles that are not well understood by the consumer. Examples of such technologies include EMI, decimation mathematics, image creation in the brain, bandwidth of the ear, phase effects, pre-ringing and reference measurement parameters. Snake Oil is a term of approbation which strongly implies that what is not understood is not valuable, rather than focusing value judgements on results achieved.

Speed Controls

It is impossible to overstate the importance of proper speed control in turntables since even very minor speed fluctuations can, under the right circumstance, be painfully audible (long, sustained piano chords are extremely revealing in this respect). For this reason, many designers have developed precision outboard power supply/speed control regulation boxes that serve to tighten up the speed accuracy of their associated turntables.

Is this just an example of ‘gilding the lily’? No. Proper speed control can make all the difference between a good turntable and a great one.

Stylus Profiles

The exact shape and dimensions of the phono cartridge stylus have much to do with how well the phono cartridge will track the record grooves. Some common stylus shapes you will encounter are the following:

Conical/Spherical: As the name suggests, conical styli are cone-shaped, but with rounded, hemispherical tips. Conical/spherical styli are the easiest to make and are the least finicky about set-up, but they have performance limitations in that they are comparatively high in mass, have relatively large tips with respect to the dimensions of the record grooves, and also provide relatively small ‘contact surfaces’ (analogous to the ‘contact patches’ of automotive tires) between the stylus and the groove.

Elliptical: An elliptical stylus represents an improvement over the conical/spherical because, rather than having a large round tip, the elliptical stylus offers a tip with an elliptical profile whose narrower edges face to the sides and directly contact the record groove. Two benefits accrue. First, the elliptical stylus is lower in mass than an equivalent conical stylus would be, and second, the elliptical stylus’ narrower but more elongated contact surface offers a better fit for purposes of tracking the undulating contours of the record groove (those narrow radius contact points can much more readily track high-frequency details, for example). Elliptical styli require somewhat more attention to set-up, but are still relatively forgiving.

Shibata: The Shibata stylus, named after its inventor, represents an even more radical step forward from the elliptical stylus in that it has an even narrower tip shape that, under a microscope, looks somewhat like the blade of a garden trowel turned so that the flatter side of the blade is facing the viewer. The side-radius of the Shibata tip is even smaller than that of an elliptical stylus so that the contact surface is not merely a somewhat elongated ellipse (as with typical elliptical styli), but rather is a much taller and narrower ellipse that almost resembles a vertical line. Relative to elliptical styli, Shibata styli offer three compelling advantages: significantly lower tip-mass, even narrower side-radius dimensions for superior tracking of high frequencies, and—somewhat unexpectedly—an increase in contact area with the record groove (meaning that even if higher tracking forces are used there is still less stylus pressure per square centimeter than with an elliptical design). Because the side-profile of the Shibata stylus is narrower and more blade-like than with elliptical designs, greater care must be taken to make sure that the stylus rake angle is properly adjusted.

Line Contact/Fine Line: Line contact/fine line styli, often attributed to the designers A.J. van den Hul and Fritz Geiger, represent an even further advancement along the same lines that inspired the Shibata stylus. The general idea is to pare away yet more stylus tip mass while narrowing the side-radius of the stylus tip, so that the stylus contact area becomes an extremely narrow and elongated ‘fine line’. But don’t let the shape and dimensions of that fine line mislead you; the fine line/line contact shape still offers plenty of stylus-to-groove contact area, so that stylus pressure per square centimeter still remains reasonable. Once again, improvements are noted in high-frequency tracking and in overall ability to trace fine, small details in the record grooves. More so than other stylus types, line contact/fine line styli are sensitive to set-up and to stylus rake angle adjustments.

Stylus Rake Angle

Stylus rake angle (SRA) refers to the front-to-back tilt angle of the phono cartridge stylus vis- à-vis the record grooves (whereas azimuth is the side-to-side tilt angle of the stylus in the groove). Unlike azimuth, however, the optimal stylus rake angle is not dead vertical (90 degrees), but rather is thought to be in the range of 91.5–92 degrees (depending upon which experts you consult), with the stylus tipped back just a bit, as if ‘scooping’ into the oncoming groove by 1.5–2 degrees.

Why is this very slight tilt back desirable? The answer is that the cutting head used to produce the lacquer master for the record also had a similar degree of tilt back. As always, for best sonic results the ideal is for the phono cartridge stylus to come as close as possible to following both the horizontal path and the vertical ‘angle of attack’ of the original cutting head.

It is possible to adjust SRA by ear, but an even more foolproof method is to use a USB microscope to observe and adjust the stylus rake angle as the stylus is resting upon the record.

Note that not all tonearms make provisions for SRA adjustments and note too that many audiophiles and even some experts tend to use the terms ‘stylus rake angle’ and ‘vertical tracking angle’ (VTA) interchangeably—even though they aren’t precisely the same thing. Sonically speaking, though, SRA is the adjustment you want to get right.

Turntables with Suspensions vs. Mass-loaded Turntables

Almost all turntable manufacturers seek to isolate key elements of their playback systems from both mechanical and airborne vibration, but there is much divergence of opinion as to how best to achieve that result.

Some designers believe in using mass loading to prevent (or at least suppress) transmission of unwanted vibrations and their designs typically use fixed, solid plinths to which the turntable platter and tonearm assemblies are firmly affixed (though turntable motors/ drive units may, in such designs, be mounted in separate housings or ‘pods’ that stand apart from the main plinth). In such mass-loaded designs, there usually is no suspension at all, apart from feet that may, in some instances, provide built-in elastomeric or spring-loaded suspension elements.

Other designers, however, strongly believe that it is best to have the turntable platter and tonearm mounted on sturdy sub-chassis that is suspended and—to a degree—isolated from its surrounding plinth. For even greater noise isolation, such designs very often attach the motor to the turntable plinth and then use an elastic belt-drive system to transfer power from the motor to the platter.

As a general rule, mass-loaded turntables are sometimes more prone to mechanically induced noise and vibration transferred via audio furniture or the floor, while suspended turntables tend to offer somewhat better vibration isolation, but at the expense of considerably more elaborate initial set-up procedures and a certain tendency to drift out of adjustment over time.

Tonearm Types

In broad strokes, there are three main types of tonearms you might encounter, although pivoted tonearms are by far the most common types. The other two types of arms are radial-tracking/ straight-line tonearms and tangential-tracking tonearms.

Pivoted Tonearms: Pivoted tonearms may feature straight or curved tonearm wands with either fixed or detachable cartridge headshells at the front end, a bearing assembly toward the rear, and a counterweight at the back end. In a pivoted arm, the cartridge/stylus always moves in an arc across the record surface, though tracing errors can be mitigated by careful adjustment of cartridge overhang and alignment angles.

Radial-tracking or ‘Straight-line’ Tonearms: Radial-tracking or straight-line tone arms almost invariably feature comparatively short, straight tonearm wands with either fixed or detachable cartridge headshells at the front end, a bearing/arm carrier assembly toward the rear, and a counterweight at the back end. What sets straight-line tonearms apart, though, are their distinctive bearing/arm-carrier assemblies, which significantly allow the tonearms to move straight sideways—not swinging in an arc as pivoted arms do. In this way, the arms realize the ideal goal of having the stylus move in a perfectly straight line across the record, always maintaining perfect tangency to the record grooves. The downside of straight-line tonearms, however, is that they are complicated to design and build, costly, and can in some instances prove difficult to set-up and to keep in proper adjustment.

Tangential-tracking Tonearms: Tangential tracking tonearms are conceptually a cross between pivoted tonearms and radial-tracking tonearms. On one hand, tangential-tracking tonearms are pivoting designs, but with one crucial difference: their cartridge headshells are not locked in a fixed position on the tonearm wand, but rather are position on an articulated mount that—get this—allows the cartridge alignment angle to be continuously adjusted during playback to maintain stylus-to-groove tangency all the way across the record. To achieve this desirable result, most tangential-tracking tonearms are built with a main tone arm wand and a secondary control arm that rides beside the main wand and that is responsible for making continuous alignment adjustments as needed. When viewed from above, tangential-tracking tonearms and their associated, articulated headshells look something like slender, elongated trapeziums. For obvious reasons, tangential-tracking tonearms must be crafted with extremely tight-tolerance bearings for the arms’ several articulated joints.

Tonearm Bearing Systems

As mentioned above, it is very important for tonearms to offer nearly friction-free movement, while preserving tonearm/cartridge/stylus geometry with great precision. To this end, designers have devoted a lot of attention to the types of bearings used. Some types commonly encountered are as shown below:

Air bearings: Air bearings are typically shaft-and-sleeve bearings where the sleeve is fed pressurized air from an external source so that the shaft never makes metal-to-metal contact with the sleeve, but rather rides on a virtually friction-free cushion of air. This type of bearing is used in a number of straight-line tone arm designs. Examples would include the Bergmann Magne, Kuzma Air Line, or Walker Proscenium Back Diamond V tonearms.

Ball/Gimbal bearings: Precision-made ball bearings are popular for use in tonearms, often via gimbal-type mounts where one pair of bearings handles horizontal axis motion, and the other pair handles vertical axis motion. Ball bearings are often graded using ABEC (Annular Bearing Engineering Committee) ratings where the higher the ABEC number the tighter the bearing tolerances are.

Knife-edge bearings: Some tonearm designs have used so-called knife-edge bearings for vertical axis applications. A knife-edge bearing consists of a knife-like blade that rides within a corresponding, precision machined V-shaped trough.

Multi-point/Kinematic bearings: Multipoint or kinematic-type bearings, as used by a handful of manufacturers, combine the precision of ball/gimbal-type bearings but offer the promise of even lower friction and essentially zero ‘free-play’ in the bearings. The general idea is to precisely locate the center of motion typically using just three or four contact points. Examples would include the Kuzma 4 Point and Wilson-Benesh ACT-series tonearms.

Thread-type bearings: Some tone arms forego traditional, metal rotational bearings and use threads not only to suspend the tonearm but also to afford it both horizontal and vertical motion. Examples would include the Well Tempered tonearms or the Funk Firm F6 tonearm.

Unipivot bearings: As their name suggests, unipivot bearing feature just a single point of contact—an idea appealing in its simplicity. Such bearings typically feature a spike (with or without a jeweled tip) that rests in a cup (again, with or without a jeweled contact surface). One point to note, though, is that arms fitted with unipivot bearings must be balanced from side-to-side in order to achieve proper azimuth alignment.

Tonearm wands/tubes, etc.

As mentioned above, tonearms must position phono cartridges precisely without introducing resonance problems. For this reason, arm wands/tubes must be strong, rigid, well damped, and as resonance-free as possible.

Most tonearm wands are constructed as tubes that can be made of metal, plastics, composites, or hybrid combinations of materials. Many manufacturers enhance tubular tonearm designs either by adding internal stiffeners or by adding dampening materials, or both.

Lately, several manufacturers have begun to experiment with 3D-printing techniques for arm wands, some using plastic-type materials and others using metal materials. 3D printing allows complex shapes/designs that could not be made via traditional machining techniques.

Tracking Force

Tracking force is the amount of downward pressure applied to the phono cartridge stylus and that is necessary in order for the stylus cleanly to track demanding material encoded in the record grooves. Above all, the intent behind using the proper amount of tracking force is to make sure the stylus remains in contact with the walls of the record grooves at all times, yet without applying so much pressure that the groove walls are damaged or subject to undue wear.

When a stylus does break contact with the record groove, even if only to a slight degree, that condition is called mis tracking, which is audible, unpleasant-sounding, and hard on the record grooves. Typical tracking forces for most modern phono cartridges will range from the mid-one-gram range to the mid-two-gram range, in accordance with published specifications for the cartridge. The general idea is to use sufficient force to eliminate mis tracking, but not more force than is necessary.

Contrary to popular assumptions it is preferable to use slightly too much tracking force than not enough. While heightened tracking force does increase record wear to a degree it also tends to help prevent mis tracking, which can be even more damaging to one’s record grooves.

Turntable Drive Systems

Turntables are often classified by the drive mechanisms they use. Some common drive mechanism types are described below.

Belt drive: In belt drive turntables the motor stands separate from the platter assembly, while a precision-made belt (typically, but not always made of elastomeric materials) transfers power from the motor drive pulley to the turntable platter (or to a sub-platter beneath the main platter). Some designs use thread or magnetic tape in lieu of an elastomeric belt. The belt is thought to decouple the platter from the motor, keeping motor noise from being transferred into the platter where it could be detected by the phono cartridge.

Direct drive: In a true direct drive turntable the ‘armature’ of a Hall-effect motor is embedded within the platter, while other parts of the motor are contained in the turntable plinth. In other words, the platter is essentially its own motor. If properly designed, direct drive turntables can be extremely quiet as their motors, by definition, rotate at platter speed and thus do not introduce higher-frequency vibrations. Also, direct drive tables—again, if properly designed—also allow extremely tight speed control.

Early generation direct drive turntables sometimes got unfavorable reviews because their designs allowed some degree of audible motor ‘cogging’ and because their speed control mechanisms sometimes introduced noise and micro-variations in speed. More contemporary designs typically address and solve both problems.

Idler-wheel drive: Idler wheel drive, sometimes confusingly called ‘direct drive’, involves a motor with a drive wheel and an idler wheel that transfers motor power to the platter. Almost the opposite of belt drive designs, idler wheel designs forge a direct coupling between the motor and the platter, so that it is imperative to base such designs on extremely low-noise motors (typically very high-quality DC motors). Proponents of idler-wheel drive praise their dynamic immediacy and solidity as well as their freedom from such micro-variations in speed as can be introduced by elastic drive belts.

Magnetic drive: Magnetic drive offers another method for transmitting power to the platter while at the same time physically decoupling the motor, per se, from the platter. In this system, the motor typically drives a substantial sub-platter, which is magnetically coupled to a physically isolated platter positioned directly above the magnetic coupler. When the subplatter rotates, its magnets attract those in the platter above, causing the platter to rotate.

Vertical Tracking Angle (VTA)

Many audiophiles and experts use the term vertical tracking angle to describe what should properly be called stylus rake angle (SRA). See above.

Wow and Flutter

The terms ‘Wow’ and ‘Flutter’ refer to two undesirable types of speed variation in turntables. Wow is a slow, gradual fluctuation that might yield a slow “Wow” sound as speed gradually increases and then decreases. Flutter is a more rapid speed fluctuation with would produce vibrato or tremolo-like sounds as speed rapidly increases or decreases. For obvious reasons, it is desirable to have turntables that produce as little wow or flutter as possible, though of the two types of speed variation flutter is arguably the more noticeable.

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Glossary: Cables https://www.theabsolutesound.com/articles/hi-fi-audio-glossary-cables/ Mon, 12 Aug 2024 20:22:18 +0000 https://www.theabsolutesound.com/?post_type=articles&p=56355 Over recent years, our online guides have created an extensive […]

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Over recent years, our online guides have created an extensive encyclopedia of audio terminology. We decided to bring these disparate dictionaries of audio terms together for the first time. This exhaustive guide is the result.

While the days of trying to baffle people with terms only the cognoscenti know are (hopefully) behind us – many readers might recall the patronizing salesman in the ‘Grammo-phone’ sketch from Not The Nine O’clock News in the early 1980s – this is still a terminology-led industry, and knowing the terms is a good idea if we are to be able to recognize how components might conceivably be different, and why.

While it’s important not to get too hung up on the terminology – we are in an industry where observed performance should always remain more important than specifications – knowing the difference between a ported loudspeaker and a sealed-box loudspeaker is important and knowing that a sealed-box loudspeaker and an infinite baffle design are basically one and the same is important, too.

 

AUDIO CABLE TERMS

High-end audio cables, much like other categories of audio components, have gradually developed a specialized vocabulary all their own. And, as sometimes happens with other types of audio products, ‘cable speak’ can at first seem confusing if not dauntingly obscure to the uninitiated. But not to worry; help is on the way. The Absolute Sound team has assembled this Glossary of Audio Cable Terms to explain cable terminology in a manner that interested laymen will be able to understand (or at least that’s the plan). Enjoy.

 

Analogue Interconnects (or Interconnects)

Analogue interconnects are audio cables specifically designed to carry low-level analogue audio signals from source components to amplification components, or from preamplifiers to power amplifiers.

Typically, analogue interconnects come in two forms: single-ended cables (in most cases fitted with RCA jacks at both ends) or balanced cables (usually fitted with a male three-pin XLR plug at one end and female three-pin XLR socket at the other end).

Balanced Interconnects

The majority of interconnects are single-ended cables that have two conductors—one carrying +/– signals and the other serving as a ground.

Balanced cables, however, are different in that they have three conductors—one for the + signal, one for the – signal, and one serving as a ground.

When properly executed, balanced audio circuits offer either higher output than or lower noise levels than equivalent single ended circuits, which allows longer runs of cables and that is why pro-audio equipment is almost universally balanced in operation. However, balanced circuits are inherently more complex to design and manufacture than equivalent single-ended circuits, and likewise balanced cables are more complex (and usually more costly) than their single ended counterparts.

Some common balanced connector types include XLR connectors (much like the connectors you might see on professional microphones), TRS or ‘tip-ring-sleeve’ connectors (which look like ¼-inch phone plugs and are more commonly seen in pro-sound rather than high-end home audio applications), and AES/EBU connectors (which are used for balanced digital audio applications).

Bi-Wiring

Some loudspeakers are configured to allow bi-wiring, which means that instead of having just one +/- pair of connection terminals, the speakers—usually, but not always, two-way designs—instead have two sets of terminal, where one set is for the low-frequency driver and the other for the high-frequency driver.

When choosing to bi-wire, users would run two complete sets of speaker cables to each loudspeaker—one routed to the low frequency driver terminals and the other to the high-frequency driver terminals. In theory, this practice can yield a purer, clearer, and more tightly focused sound overall.

Several technical explanations are offered to explain the ostensible benefits of bi-wiring, but opinions on the efficacy of bi-wiring can and do vary among high-end cable designers.

When choosing not to bi-wire, users would instead run a single primary set of speaker cables to their loudspeakers—typically to the terminals for the low-frequency driver, and then would run a set of short ‘jumper’ cables (ideally identical in configuration to the main cables) from the low-frequency driver terminals to their adjacent high-frequency driver terminals.

Capacitance, Resistance, & Inductance

These three electrical characteristics are the basic building blocks of all high-end cable designs; they are the essential variables that cable designers seek to manipulate in their quest for higher performance and better sound.

Capacitance is the ability of a cable (or a capacitor) to store an electrical charge.

Generally speaking, most designers consider that lower capacitance is better. The train of thought is that one does not want an audio cable to absorb and store an electrical charge from the music signals being passed through the cable, because such charges will inevitably be released (or dissipated) later on in time, thus ‘smearing’ the sound of the music.

Inductance is the property of cable (or an inductor) to resist changes in current flowing through the cable through the process of inducing an electromotive force (EMF), which actively resists current changes. Generally speaking, most designers consider that lower inductance is better, since ideally one would want cables to allow current changes to occur in a natural or free-flowing manner as required by changes in the music signal.

Resistance is a measure of the difficulty to pass an electrical current through a conductor—in this case a cable. Generally speaking, most designers consider that lower resistance is better, since the lower the resistance the less energy is dissipated within the cable when driving current through the cable. This factor can be especially important in designing cables that are meant to conduct very low-level audio signals with minimum signal loss and distortion.

Coaxial Cable

A type of cable construction often used in digital or single-ended interconnects with a central +/- signal conductor surrounded by an insulating (dielectric layer), in turn surrounded by an outer conductive shield or sheath used as a ground or ‘return’, with a protective insulation jacket on the outside. The central conductor and the conductive sheath both share the same axis; hence the term ‘coaxial’.

Conductors

Technically, conductors are materials that permit electrons to flow freely and that allow electrical current to flow in one or more directions. Wires, in turn, are conductors that can carry electricity over their entire length. Conductive materials used in audio cables include copper, silver, gold, rhodium, and in some recent exotic designs, palladium and graphene. At least one manufacturer uses liquid metal conductors made from gallium, indium, and tin.

Depending on which designer one asks, the exact composition of wires, both in terms of the conductive materials used, the metallurgy of the wire, and even the cross-sectional characteristics of the conductors, are thought to have significant impact on sound quality.

Stranded-Core designs: In many cases the wires used in audio cables are composed of multiple, bundled, small-diameter strands of conductive materials—collectively known as stranded-core designs.

Solid-Core designs: In other typically higher-end audio cables, wires use solid-core conductors that are considerably larger in cross-sectional area than the tiny conductive strands used in stranded-core designs. The size and shape of the solid-core conductors used are thought to have an impact on sound.

Thus, at least one famous cable manufacturer touts the use of ‘rectangular solid core’ conductors, while another uses solid core conductors whose also rectangular cross section uses so-called ‘Golden Section’ proportions.

In a ‘big picture’ sense, the better the conductors an audio cable employs, the better it will sound.

Crystal or Monocrystal Conductors

The overwhelming majority of audio cables use metal conductors, but what few listeners realize is that the wires within those cables have a crystalline structure (many equate ‘crystals’ with gemstones, but metals are crystalline, too).

Under normal circumstances, drawn metal wires contain numerous metal crystals butted up against one another and many audio purists believe that the junctures between these crystals have a subtle, adverse effect upon sound quality.

However, one important development is the advent of manufacturing techniques that allow wire makers to produce monocrystal wires, where one metal crystal spans the entire length of the wires (meaning there are no crystal-to-crystal junctions to affect the sound in any way).

Cables featuring monocrystal conductors are highly prized for high-purity/high-accuracy applications, even though they are typically more expensive to make than conventional multi-crystal conductors.

Dielectrics

In simple terms, dielectrics are insulators—the materials or other related systems used to provide insulation for the conductors found in audio cables.

Dielectrics are important because they have much to do with the cable’s capacitance and thus resulting sound quality (see ‘Capacitance/ Inductance/Resistance’). The ideal would be to have dielectrics that absorb no electrical charges at all.

Some common dielectrics include fluorinated ethylene polypropylene (FEP), polyethylene, polytetrafluoroethylene (PTFE, aka Teflon), and others—many of which are available either as solid or as “foamed” materials. Several manufacturers have experimented with insulation systems that use air or a vacuum as dielectrics (because, in theory, a perfect vacuum would be an ideal insulator, though for obvious reason vacuums are very difficult to manage in a cable context).

Dielectric Bias System (DBS)

DBS is AudioQuest’s trade name for a system (co-developed with loudspeaker designer Richard Vandersteen) for applying a bias voltage (via a small battery) across the dielectrics of audio cables, effectively making them highly resistant to accepting music-induced electrical charges. One claimed advantage of DBS is that it obviates the need for lengthy cable ‘break-in’ periods.

Digital Interconnects

Audio cables specifically designed for carrying low-level digital signals (or files) from digital source components (e.g., a CD transport, music server, or streamer) to a digital audio component capable of decoding those signals.

At first glance, it is tempting to think of digital interconnects as being ‘just like’ analogue interconnects, but in fact the two cable types have significantly different ‘mission profiles’. Analogue cables must accurately convey analogue signals ranging in frequency from a few Hz on up into the kHz range.

Digital cables, instead, are expected to transfer square wave signals (representing digital ‘ones’ and ‘zeroes’) in the MHz range, loading into digital components whose input impedances are potentially quite different to analogue components.

Some common digital interface types include:

  • AES/EBU (Audio Engineering Society/European Broadcasting Union)—a quiet, balanced digital audio interface that uses XLR-type connectors.
  • Ethernet—a reliable, well-documented, wide-bandwidth multipurpose digital connection borrowed from the computer world, which typically uses RJ-45-type connectors and sockets.
  • S/PDIF (Sony/Philips Digital Interface Format)—a popular and robust digital audio interface that typically uses coaxial wires with RCA-type plugs.
  • TOSLINK (Toshiba Link)—a popular and robust digital audio interface that, instead of wires, uses fiber-optic connections that typically use EIAJ/JEITA RC-5720 optical connectors. Note: TOSLINK is essentially a fiber-optic implementation of the S/PDIF standard.
  • USB (Universal Serial Bus)—an enormously popular, multi-purpose digital interface that has in recent years come to be the digital interface of choice for many high-end (and not-so-high-end) digital audio components. The USB specification allows for many types of connectors, but the ones most commonly seen in audio applications are: USB Type A (as found on many PCs and other digital sources), USB Type B (as found on many high-end audio DACs), USB Mini A – USB Mini B and now USB C (used on many smartphones and portable digital audio components).
  • Lightning (Apple)—Since Apple removed the 3.5mm mini-jack from its popular iPhone range, the company’s own connector has become increasingly important in digital audio replay on the move.

Directionality in cables

Although the subject is considered somewhat controversial, the fact is that most if not all audio cables (or more accurately, the conductors within those cables) exhibit directionality—meaning that signal flow works and sounds better running in one direction than the other. The technical explanations behind this are somewhat complex, but according to AudioQuest founder Bill Low:

“All drawn metal has a directional impedance variation at higher RF/EMI noise frequencies. By ‘law’, energy must follow the path of least resistance, so we employ this impedance variation as a mechanism for consciously directing noise either to Earth or to whichever attached circuit is less vulnerable to noise. The key is to direct noise to where it will do the least damage.”

What is more, some cable designs use asymmetrical shielding schemes (where noise blocking outer sheaths might be, for instance, connected to ground only at one end of a given cable), adding a further directional element.

Given this, expect to see markings (arrows, marker rings, and the like) on many high-end audio cables to indicate the preferred direction of signal flow. Some speaker cables, for instance, even provide terminations marked ‘speaker end’ or ‘amplifier end’.

Gauge (or Wire Gauge)

The gauge of a cable, typically expressed as AWG (American Wire Gauge), is an indicator of the cross-sectional area of the wires used in the cable. AWG ratings are arranged so that the lower the AWG number, the more cross-sectional surface area the cable possesses. A giant power cord, for instance would have a very low AWG number, while the tiny run-out wires in a tonearm headshell would have a very high AWG number. Note: AWG numbers are considered useful indicators of a cable’s current carrying capacity (the lower the AWG or gauge number, the higher the current load the cable can bear).

Hospital Grade Power Plugs/Sockets

In discussions of American AC power distribution, we often encounter references to ‘hospital grade’ mains sockets and plugs. The reference is to specifications for mains sockets and mains cable plugs designed for use in ‘mission critical’ hospital applications (you wouldn’t want an AC plug to fail on a respirator, now, would you?).

Hospital grade sockets and plugs specify materials that can withstand both chemical and physical abuse and, in the case of plugs, also specify relatively tight-fitting connector pins that, by design, are difficult to dislodge.

There is no direct UK equivalent to the ‘hospital grade’ socket (in part because the three-pin socket used in the UK is hard to dislodge), but audiophiles in the UK often opt for unswitched 13A designs in place of standard switched models.

There is much debate over whether hospital grade mains connections are necessary or beneficial for audio applications, but many purists choose to use them (both for mains cables and for power distribution components)—if only as a precautionary measure.

“The most common result of skin effect is a tendency for a cable’s AC resistance to increase at higher frequencies.”

Litz wire

Litz wire is a specific cable configuration that uses bundles of multiple small-diameter, individually insulated strands of conductors, where the strands are typically twisted along the length of the cable. The main intent behind Litz wire is to mitigate the sonic problems associated with skin effect (see ‘Skin Effect’).

The most common result of skin effect is a tendency for a cable’s AC resistance to increase at higher frequencies, potentially causing at least some degree of audible treble roll-off. Happily, Litz wire overcomes this problem for the most part.

A few power amplifiers designed to be used with conventional stranded loudspeaker cable have been known to ‘struggle’ with the low resistance of Litz wire. Fortunately, in every cases we know of, these problems were resolved in the 1980s and are now historic.

Mains or Power Jacks & Plugs

Often, we think of our own AC connections as the norm, forgetting that there are actually numerous international standards for power distribution voltages, frequencies, and the sockets and plugs to deliver electrical power. The US Department of Commerce International Trade Association has identified 15 specific types of power plugs/ sockets in use worldwide (these plug socket combinations are assigned identifying letters from A through O).

The tricky part, however, is that various countries and regions use these 15 types of power plugs, some grounded and others not, in sometimes unusual or unexpected combinations.

One upshot of all this diversity is that high-end audio power cable manufacturers must potentially create very broad ranges of models in order to address the needs of the worldwide market.

Ohno Continuous Casting (OCC)

Under ‘Crystal/Monocrystal Conductors’, we mentioned that ‘monocrystal conductors are highly prized for high-purity/high-accuracy applications’. The man who successfully developed the manufacturing process that makes it possible to fabricate monocrystal wires is Dr Atsumi Ohno, and his famous process is called Ohno Continuous Casting, typically abbreviated ‘OCC’, not to be confused with the familiar psychological acronym, OCD.

Plugs, Lugs & Jacks for analogue audio cables

Audio cables use a wide variety of connectors, with certain connectors optimized for interconnects and others for speaker cables. When thinking about connectors it is helpful at times to remember that for plugs and lugs there is always a corresponding jacket, socket, or terminal to complete the connection.

Banana plugs and jacks: Banana plugs are extremely popular as terminations for loudspeaker cables. (The spring-loaded connector surfaces of the male Banana

plug look somewhat like miniature, metal ‘bananas’—hence, the name.) Banana plugs typically connect to loudspeaker cable-binding posts that, by design, have banana jacks bored into their outer ends. Banana plugs are very easy to use, allowing simple push-to-connect, pull-to-disconnect operations.

Banana plugs typically make a ‘press-fit’ connection with their associated sockets. Note, however, that some banana plugs are ‘locking’ designs, with thumbscrews that, when tightened, clinch the plugs for an extremely tight fit within their jacks.

BFA connectors: Built For Audio/British Federation of Audio terminations are a variation on the theme of the 4mm banana plug (effectively built inside out and coated in ABS), designed to express safety concerns raised because the similarity of this plug to the live and neutral terminals in a EU ‘Schuko’ AC terminal. The 4mm banana plug is (notionally at least) ‘banned’ in the EU, which is why amplifiers include little red and black inserts that prevent their use, but you can remove these inserts with a penknife and continue to use banana plugs as before.

BNC connectors: Male BNC (Bayonet Neill Concelman) connectors are sometimes used on coaxial interconnect cables for use with components fitted with female BNC connectors, although BNC interfaces are relatively uncommon in high-end audio applications and components. Male BNC connectors use a quickconnect, quick-disconnect, twist-to-lock collar or ‘nut’ that latches on to two bayonet locking pins found on the female BNC connector.

BNC connectors are desirable in settings where it is important (or even critical) that cable connections do not work loose and where a ‘fail-safe’ locking mechanism is therefore required.

RCA plugs and jacks: RCA plugs are the de facto standard terminations for analogue interconnects and for coaxial S/PDIF digital interconnects. Corresponding, RCA jacks are the standard socket fitments for single-ended analogue and coaxial S/PDIF interfaces on audio components. RCA plugs provide a central post, carrying +/- audio signals, and an outer sleeve that serves as a ground, or ‘return’.

As with banana plugs, RCA plugs make press-fit connections with their associated sockets. However, many audiophile-grade RCA plugs feature ‘locking’ mechanisms, most of which work on the principle of firmly clamping the plug’s outer sleeve against the mating surface on the RCA jack.

Spade lugs: Spade lugs vie with banana plugs as the most popular terminations for loudspeaker cables. Spade lugs, as their name suggests, look almost like miniature, metal garden implements. Typically, spade lugs provide a sturdy wire receptacle at one end (where the cable’s conductors attach to the lug), and a flat, thick, two-pronged metal connecting surface at the other end, which is designed to fit around the central shaft of a traditional loudspeaker binding post.

Loudspeaker cable-binding posts have threaded metal shafts, traditionally fitted with beefy metal locking nuts or collars. To make firm connections using spade lugs, one would first back off the binding post’s locking nut, then insert the spade lug so that its prongs fit on either side of the binding post shaft, and finally tighten down the locking nut or collar as firmly as feasible to clinch the spade lug in place.

Some contend that spade lugs offer inherently superior connections to banana plugs owing to their robust construction and large surface area, but one point to bear in mind is that it takes two hands to connect spade lugs properly—one hand to hold the spade lug in place against the binding post shaft while the other tightens the locking nut. Also, users should be aware that—depending upon cable positioning—the weight of the speaker cables can apply torque on the spade lugs, causing the binding post locking collars to become loose over time.

XLR connectors: XLR connectors are the de facto standard for use in all types of balanced analogue and digital interconnects. In traditional, loudspeaker-based audio systems, the most common variant would be three-pin XLR connectors where, as noted under ‘Balanced Interconnects’ and ‘Digital Interconnects’ above, one pin carries the + signal, another carries the – signal, and the third serves as the ground, or ‘return’.

By convention, three-pin XLR output jacks provide a socket with three outward-facing pins, while XLR input jacks provide a socket with three pin receptacles. To accommodate this convention, XLR cables are invariably set up with different connectors on each end, with a distinct signal input end (providing receptacles for the pins from the audio component’s XLR output socket) and a signal output end (providing outward-facing pins that plug in to the receptacles of the audio component’s XLR input sockets). Virtually all XLR sockets and plugs features spring loaded mechanical latches that lock the connectors firmly in place (typically the latches feature thumb-actuated release catches).

In headphone-based systems, however, one might encounter both three-pin or four-pin XLR connectors, where the four-pin variant is a stereo (two-channel) connector, providing two sets of +/– connections pins. Some higher-end headphones ship with balanced signal cable sets terminated either with dual three-pin XLR connectors (as used, for example, on the Abyss AB-1266) or with single four-pin XLR cables (as used, for example, on top-tier Audeze or HiFiMAN headphones).

“If you could only improve one cable in your entire system, it should be the mains cable that runs from your wall sockets.”

Power Cords or Mains Cables

You might think all mains cables are created equal (or nearly so), but in our experience, high-performance mains cables can and do have a profound effect on sound quality. Indeed, several leading-edge cable designers would say that, if you could only improve one cable in your entire system, it should be the mains cable that runs from your wall sockets to whatever power distribution component you choose to use.

The key differentiators between ‘garden-variety’ power cords and the high-performance models we recommend include: higher gauge conductors, conductors fashioned from superior and very high-purity materials, more sophisticated dielectrics, superior internal geometries (often focused on blocking noise), superior shielding schemas (again, focused on blocking noise), and ultra high-quality plugs at both ends of the cables.

Purity of Conductors

High-purity conductors are thought to have a direct and significant impact on sound quality and for this reason a number of purity-related acronyms and terms have come into play. Here are three you might encounter frequently:

HPC (high purity copper): Manufacturers who use copper conductors and have been selective in their choice of materials suppliers will often say that their cables feature HPC conductors. Caveat emptor: The term HPC implies that care was used in choosing sources of copper wire, but it does not tell you precisely how pure the copper actually is (although some manufacturers might clarify this point with additional specifications).

OFC (oxygen free copper): Oxygen is one of the most common ‘contaminates’ of pure copper, so manufacturers who have taken steps to source copper that is very low in oxygen content will often tout their use of OFC conductors. In many cases, references to OFC conductors will feature supplementary specifications to indicate the exact-level of purity.

‘Five-Nines’ or ‘Six-Nines’ conductors: These slang terms indicate levels of purity, expressed as, for example, 99.999% or 99.9999% pure metal, whether referencing copper, silver, or other metals. Obviously, more ‘nines’ describe conductors of higher purity, higher cost, and—it is thought—higher sound quality.

Skin Effect

Skin effect is the tendency for an alternating current (AC), or an alternating music signal, to flow or become concentrated mostly near the outer surface (or skin) of a conductor. The higher the frequency of the signal the thinner the functional depth of the skin being used to pass the signal, which means that the AC resistance of the cable tends to increase at higher frequencies. This is why some cables can exhibit a certain degree of treble roll-off.

Certain cable geometries (for example, woven Litz wire geometries) can, however, mitigate the problem of AC resistance increasing at high frequencies owing to skin effect. The point is that it pays to seek out cables whose designs minimize or eliminate skin effect problems in the audio range.

Snake Oil

A term used by consumers to describe products that involve technological principles that are not well understood by the consumer. Examples of such technologies include EMI, decimation mathematics, image creation in the brain, bandwidth of the ear, phase effects, pre-ringing and reference measurement parameters. Snake Oil is a term of approbation which strongly implies that what is not understood is not valuable, rather than focusing value judgements on results achieved.

Speaker Cables

Some audiophiles draw a distinction between ‘signal-bearing’ cables (namely, interconnects) versus ‘power-bearing’ cables (namely, speaker cables). Stated another way, speaker cables are responsible for delivering the

often high-wattage output of amplifiers to our loudspeakers and doing so with high bandwidth, minimum noise, low distortion and coloration, and maximum delivery of current as demanded by the loudspeaker.

To meet these demands, speaker cables place the same emphasis on geometries, materials, conductors, and noise-blocking shields as interconnects do, but with the added demand of being able to handle potentially very high levels of power (power = voltage x amperage).

Some speaker cable terms you may encounter are these:

(Internal) Bi-wire cable: A speaker cable that internally has double runs of conductors, with a single pair of +/- connections at the amplifier end and a double set of +/- connections at the loudspeaker end. In this configuration, the double runs of conductors are housed within a common sheath or jacket.

‘Shotgun’ cable: A speaker cable that provides double runs of conductors, each housed in its own sheath or jacket, where there is a single +/- set of amplifier connections and a double set of +/- connections at the speaker end. The term ‘shotgun’ comes from the fact that the dual-runs of conductions, each in its own jacket, look somewhat like the barrels of a double-barrel shotgun.

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Glossary: Headphones https://www.theabsolutesound.com/articles/hi-fi-audio-glossary-headphones/ Mon, 12 Aug 2024 18:26:54 +0000 https://www.theabsolutesound.com/?post_type=articles&p=56335 Over recent years, our online guides have created an extensive […]

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Over recent years, our online guides have created an extensive encyclopedia of audio terminology. We decided to bring these disparate dictionaries of audio terms together for the first time. This exhaustive guide is the result.

While the days of trying to baffle people with terms only the cognoscenti know are (hopefully) behind us – many readers might recall the patronizing salesman in the ‘Grammo-phone’ sketch from Not The Nine O’clock News in the early 1980s – this is still a terminology-led industry, and knowing the terms is a good idea if we are to be able to recognize how components might conceivably be different, and why.

While it’s important not to get too hung up on the terminology – we are in an industry where observed performance should always remain more important than specifications – knowing the difference between a ported loudspeaker and a sealed-box loudspeaker is important and knowing that a sealed-box loudspeaker and an infinite baffle design are basically one and the same is important, too.

 

ENCYCLOPAEDIA HEADPHONICA

As you might expect, the world of high‑performance headphones and earphones has gradually adopted specialized terminology all its own. This article is provided in an attempt to make it easier for newcomers and veterans alike to navigate that world.
Some of the terms described here are in common use throughout the industry, while others are more specific to The Absolute Sound. Our publication does try to use terminology consistently, especially within our on-going series of headphone/earphone-related product reviews, so that this glossary will—we hope— help you get more out of past, present, and future The Absolute Sound content.

 

Balanced Armature Driver

A type of miniature drive unit frequently applied in earphone and CIEM designs, but also—much less frequently—used in full-size headphone designs. Balanced armature drivers feature extremely small can-like enclosures containing very small armatures wound with wire coils and suspended within a magnetic field. As audio signals are applied, the changes in the magnetic field across the coil cause the armature to rock back and forth, pivoting on its balance point or fulcrum. As one end of the armature is driven upward, the other end goes downward (much like a child’s ‘seesaw’ or ‘teeter-totter’ in motion). In order to produce sound, one end of the armature drives an actuator connected to an extremely small diaphragm, which flexes inward and outward as the armature moves up and down. Output from the diaphragm typically is routed to the listener’s ears via a sound outlet tube commonly called a ‘bore’.

Balanced Headphone Amplifiers

In the world of headphones and earphones—as in traditional audio—there are two distinct topologies of amplifiers available: single-ended amplifiers and balanced amplifiers. By convention, in a single-ended amplifier the ‘–‘ output terminal is tied to electrical ground, while the ‘+’ terminal carries the active signal. In single-ended headphone amplifier

applications specifically, outputs are typically delivered through a three-conductor jack sized to fit either a 6.35mm phone jack-type plug or a 3.5mm mini-jack-type plug. In either case, one of the conductors in the jack/plug serves as the ‘–‘ or ground connection, while the other two conductors serve, respectively, as the ‘+’ connections for the left and right audio channels.

In balanced (some would call them ‘differential’) amplifiers, internal circuitry is differently arranged so that in essence the amplifier has two equal but opposite halves; one handling the positive-going side of the audio signal and the other handling the negative-going side of the signal. Both the ‘+’ and ‘–‘ halves of the amplifier are referenced to electrical ground. As a result, the outputs of each amplifier channel will have three (rather than just two) connections for audio signals: a ‘+’ connection, a ‘–‘ connection, and a dedicated ‘GND’ or ground connection. In balanced headphone amplifiers, outputs are typically handled by two 3-pin XLR connectors (one for the left channel and the other for the right), where the 3-pins correspond to ‘+’, ‘–‘, and ‘GND’.

Note the multiple types of balanced output connectors on the front panel of the iFi Audio Pro iCAN fully-balanced headphone amplifier.

Bore

Many CIEM and some earphone manufacturers use the term ‘bore’ to describe the sound outlet tubes associated with balanced armature-type drivers. Sometimes the outputs of multiple drivers might be routed through a single bore tube. Thus, one might read CIEM descriptions that state something like this: “Ours is a four-driver, triple-bore in-ear monitor design.”

CIEM

CIEM is an increasingly popular acronym that stands for ‘Custom-fit In-Ear Monitor’. The key idea is that CIEMs, unlike universal-fit earphones, have custom-molded earpieces that are crafted to provide a precise custom-fit that exactly matches the contours of the individual wearer’s ear canals and outer ears (or pinnae).

In order to have a set of CIEMs made, prospective owners must first obtain, either through a qualified audiologist or through the CIEM manufacturer, a set of ear-mold impressions, or else have the interior surfaces of their ears digitally scanned. Either way, the ear-mold impression or digital scans are used to create molds from which the CIEM’s custom earpieces are made.

CIEMs like the Westone ES80 offer beautifully finished, user-specific, custom-molded earpieces.

Circumaural Headphones

Full-size headphones generally come in two forms: on-ear designs and around-the-ear designs. The word ‘Circumaural’ is the correct, formal term for ‘around-the-ear’ designs, where the ear pads surround the wearer’s outer ears, but do not rest directly upon them.

Clamping Force

The term ‘Clamping Force’ describes the amount of pressure that a given headphone design exerts in squeezing or pressing the left and right ear cups of headphones against the sides of the wearer’s head. There is no industry standard for such forces and listener’s tastes can and do vary on the matter. The key concept is to have sufficient force for the headphone to stay in place during listening (too little clamping force might make the headphone prone to slipping out of position or even falling off) but force low enough to allow comfortable long-term listening sessions.

Closed‑Back Headphones

Generally speaking, full-size headphone designs follow one of two possible configuration formats: open-back or closed-back designs. In closed-back designs, as the terminology suggest, the back sides of the ear cups are completely sealed or ‘closed’—making each ear cup much like the enclosure of an acoustic suspension-type loudspeaker, but in miniature. For obvious reasons, closed-back headphones do a better job of blocking out external noise than open-back headphones do. However, there is much debate on which design format— open-back or closed-back—makes for superior driver performance and all-around sound quality.

Closed-back headphones like the Sennheiser HD820 have ear cups completely sealed on the back side.

Diaphragm

Regardless of type, headphone and earphone/ CIEM drivers invariably have some sort of diaphragm, which is the moving element that actually produces the sounds we hear.

Some headphone/earphone diaphragms are much like miniature versions of the circular woofers, tweeters, etc. that most of us have seen in conventional dynamic driver-equipped loudspeakers; these tiny diaphragms operate like tiny pistons moving inward and outward to produce sound waves.

Other headphone/earphone diaphragms are thin, planar membranes whose entire surface area vibrates to produce sound, much as in full-size electrostatic or planar magnetic-type loudspeakers.

Finally, some headphone drivers used folded membranes whose pleated surfaces move somewhat like the bellows of an accordion to produce sound, much like loudspeakers fitted with ribbon-type or Heil air motion transformer (AMT) types of drivers.

Dynamic Driver (Moving‑Coil Driver)

Dynamic drivers (also sometimes called ‘moving-coil’ or ‘pistonic drivers’) are by far the most popular types of drivers for use in loudspeakers, headphones, and earphones (although many CIEMs use balanced armature-type drivers). The core elements of dynamic drivers consist of diaphragms (the cone or dome that actually moves to produce sound), voice coils (ring-shaped coils of wire wound on small, cylindrical ‘voice coil formers’) that are attached to the diaphragm, and magnets (which are usually cylindrical in shape with ring-shaped grooves called ‘voice coil gaps’ on top).

As a musical signal is routed through the voice coil, which is positioned within the voice coil gap of the magnet, the electromagnetic interaction between the voice coil and the magnetic field causes the voice coil/diaphragm to move forward and backward, thus producing sound.

Dynamic headphone drivers like the Beyerdynamics’ T1 Tesla headphone are built much like miniaturized dynamic drivers for loudspeakers.

Ear Buds

The term ‘ear bud’ is the slang expression for the sort of loose-fitting transducers worn in the outer ear, as typically supplied with smartphones, personal digital music players, etc.

Some people use the terms ‘ear bud’ and ‘earphone’ interchangeably, but we at Hi‑Fi+ see those terms as having distinctly different meanings. For us, the defining characteristics of ear buds are, first, that they are worn in the outer ear and not within the ear canal, and second, that ear buds almost always fit loosely and do not provide any sort of airtight seal with the ear canal. Note, please, that ear buds typically are voiced so that they sound normally balanced without requiring an airtight seal.

Ear buds such as the Urbanears Medis are meant to rest lightly in the wearer’s outer ear— not inserted into the ear canal.

Ear Cup

In full-size headphones, ear cups are the physical housings or ‘enclosures’ to which the headphones’ drivers are attached, and to which the headphones’ ear pads are attached.

Typically, signal wire connections to the headphone are also made through the ear cups. There are many different schools of thought on ear cup construction so that you will find ear cups made of wood, molded thermoplastics, composites, and metal.

Ear cups can be made of various materials, including polycarbonate, carbon-fiber, and a range of exotic woods.

Earphone

The Absolute Sound (and many manufacturers and enthusiasts) consider the term ‘earphone’ to be a contraction of the longer though more descriptive term, ‘universal-fit in-ear headphone’. For us, the defining characteristics of earphones involve the fact that, regardless of the earpiece configuration used, earphones are meant to be worn within the ear canal, with the assumption that a flexible set of ear tips (offered in various sizes) will be used to ensure a comfortable yet airtight seal between the earphone and the ear canal. The voicing of earphones presumes and indeed requires this airtight seal for proper tonal balance to be achieved.

Some people use the terms ‘earphone’ and ‘in-ear monitor’, plus the acronym ‘IEM’, interchangeably, but at Hi‑Fi+ we again feel these terms have distinct and different meanings.

As above, we define ear buds as typically loose-fitting devices worn in the outer ear, while ‘earphones’ are worn within the ear canal and require the aforementioned airtight seal within the ear canal in order to work properly, in the process achieving significant levels of noise isolation.

‘In-ear monitors’ and ‘IEMs’ are, strictly speaking, in-ear transducers worn for monitoring applications, but the practical reality is that the majority of listeners doing actual monitoring work tend to choose CIEMs (Custom-fit In-Ear Monitors) for the job, owing to their superior noise isolation and more sophisticated sound quality.

In our opinion, most earphone makers who call their products ‘IEMs’ are overreaching, probably in the hope that the ‘IEM’ label will confer upon their earphones some of the perceived ‘hipness’ and sophistication of true CIEMs.

By design, earphones are compact and use sound outlet tubes fitted with flexible ear tips designed to create a comfortable yet airtight seal within the wearer’s ear canals.

Earpiece

The term ‘earpiece’ refers to the physical housing or enclosure within which ear bud, earphone, or CIEM driver(s) and crossover networks (if any) are mounted and from which the sound outlet tube(s), if any, extend.

For obvious reasons, earpieces must be large enough to accommodate the intended driver or driver arrays, yet small enough and smooth enough to fit comfortably within the wearer’s outer ears. The physical shape of the earpiece must also allow for very wide variations in ear shapes and sizes, while at the same being easy for the wearer to grasp, to insert, or to remove.

As with headphone ear cups, there are many schools of thought on earpiece construction, so that shoppers may encounter earpieces made of wood, molded thermoplastics, composites, metal, acrylic materials, or even cold-cure soft-gel silicone.

Manufacturers go to great lengths to balance the demands of fit and functionality in high-performance earpiece designs.

Ear Pads

All types of full-size headphones feature ear pads that provide a comfortable, soft, and flexible interface between the headphones’ ear cup/driver assemblies and the wearer’s head.

Ear pads typically are shaped either as circular, oval, or ‘racetrack’-like rings, open at the center to allow the sound to pass through; pads may be covered in fabric, leather, faux leather, or any combination of those materials.

Ear Tips

Almost all contemporary universal-fit earphones come with several sizes of flexible ear tips designed to provide a comfortable but airtight seal between the earphone’s sound outlet tubes and the wearer’s ear canals (even a seemingly minor air leak can upset if not ruin the tonal balance of the earphone). The sole exception would be certain ear tip designs that provide built-in vents (e.g., some of the tips used for the Cardas Ear Speakers) though vented ear tip designs are comparatively rare.

Ear tips come in a variety of configurations with popular variations including single-, double-, and triple-flange designs, and round or ‘bell-shaped’ designs that might also include special features designed to enhance noise isolation. Ear tips are typically made of soft, silicone rubber, but some manufacturers have experimented with multi-layer ear tips, in some cases with noise isolation gel sandwiched between the inner and outer layers. Another popular variation involves ear tips constructed of compressible foam materials—a concept patented by the firm Comply Foam (which is a spin-off of 3M Corporation).

Modern universal-fit earphones, such as the Campfire Audio Solaris ship with extremely elaborate sets of ear tips.

Electrostatic Drivers

Electrostatic drivers feature diaphragms made of thin membranes typically constructed of polyester-like materials (e.g., polyethylene terephthalate or PET) to which an electrically conductive coating has been applied. These membranes carry a high voltage (typically greater than 500V) but very low-current charge and are suspended between two metal (or metallized), mesh-like electrode grids called stators.

In operation, high voltage (but again, typically low-current) audio signals are applied to the stators. By design, the stator pairs are configured so that at any time when musical signals are present, the stators will carry opposite charges (one carrying a negative ‘–‘ charge and the other a positive ‘+’ charge, and then vice-versa, as the audio signal flows back and forth).

As the charge on the stators varies in response to musical signals, the diaphragm is simultaneously attracted to one stator and repelled from the other, so that the diaphragm moves back and forth within the air gap between the stators, producing sound as a result.

Headband & Headband Frame

In a general sense headbands are the frames used on all full-size headphones that reach up and over the top of the wearer’s head, while holding the left and right ear cups in proper position for optimal sound and user comfort. Frames can be made of various materials including metal, molded thermoplastics, composites, or other materials.

One key aspect of any headband design will be an adjustment mechanism of some kind that will allow the frame to expand or contract as needed in order to accommodate the varying sizes of users’ heads. Two other key elements of any good headband frame will be the ear cup yokes and the headband pad or strap.

Ear cup yokes are the frame elements to which the headphones ear cup/driver assemblies attach. Some yoke designs are minimal while others are quite elaborate. Some minimalist yoke designs hold the ear cups in fixed, or very nearly fixed, positions, trusting in the springiness of the headband frame to provide sufficient flex for a decent fit. Other yoke designs allow ear cups to swivel (in horizontal and/or vertical axes) to obtain a better overall fit. Trade-offs can be involved either way. As a general rule, minimalist yoke designs tend to be more rugged—say, for headphones that might be worn while participating in action sports, while swiveling designs offer greater flexibility for purposes of fit but are somewhat more complicated to build and more prone to breakage should the headphone inadvertently be dropped.

The frame and yoke design of the HiFiMAN Susvara headphone allows ear cups to swivel in both horizontal and vertical axes.

Headband pads or straps are the ‘suspension system’ for the headphone, enabling the headphone’s weight to be spread across the top of the wearer’s head. One school of thought calls for padding the headphone frame itself to provide a soft, comfortable point of contact with the wearer’s head. A second school of thought, however, calls for a broad, flexible strap to be suspended, sometimes via elastic or rubber suspension rings, from the frame of the headphone (so that the weight of the headphone is borne, in part, by the suspension bands or rings).

For example, the MrSpeakers ETHER 2 uses a lightweight suspension strap to support the headphone’s weight for greater comfort.

Headphone

The term ‘Headphone’ refers’ to full-size headphones (as opposed to earphones or CIEMs) that are worn on the head, with ear cups that either fit around or alternatively rest upon the listener’s ears.

We at The Absolute Sound draw a distinction between headphones, which by definition are worn on and rest upon the user’s head, versus earphones or CIEMs, which are worn in the user’s ears but do not rest upon the top of the head.

Headphone Connector Plugs

There are a handful of physical connector types commonly used for connections between headphones and headphone amplifiers (or tablets, smartphones, etc.). One useful distinction, however, can be drawn between connectors designed for use with single-ended amplifiers vs. connectors designed for use with balanced amplifiers.

Single‑ended Connector Plugs: Single-ended connector plugs have three conductors—a ground “GND’ conductor (shared by both the left and right channels), plus two ‘+/–‘ signal conductors (one each for the left and right channels).

3.5mm, three‑conductor, mini‑jack plug: By far the most common connector for earphones/ CIEMs (but also for some headphones), the small, three-conductor 3.5mm mini-jack

plug is the type of connector used to plug headphones into iPods, digital music players, iPads and other tablets, and iPhones and other smartphones. Quite recently, some manufacturers have begun using pairs of 3.5mm sockets to support balanced stereo output connections.

3.5mm plugs are probably the most common in all of personal audio because 100 years of jack plugs makes them ubiquitous!

6.35mm phone/headphone plug: Think of this as a considerably larger scale version of the 3.5mm plug. The 6.35mm plug is typically used to connect full-size headphones to full-size desktop (but also some portable) headphone amplifiers. Like the 3.5mm plug, the 6.35mm plug provides three conductors (sometimes called the Tip, Ring, and Sleeve) and supports connections to single-ended amplifiers.

6.35mm plugs, like this ‘garden variety’ adapter plug, are essentially bigger, sturdier version of 3.5mm plugs.

Balanced Connector Plugs: Balanced connector plugs will typically provide four, or in some cases two sets of three, conductors— with separate ‘+’ and ‘–‘ conductors for each channel, plus a separate ground ‘GND’ conductors in some configurations.

Three‑Pin XLR connector plug: Three-pin XLR connector plugs are designed specifically for balanced signal connections and in headphone contexts are always used in pairs (one for each channel in a stereo pair of balanced mode connections). The three pins provide ‘+’, ‘–‘, and ‘GND’ connections for one channel: hence, the need for two plugs to provide stereo (two-channel) connections.

Traditional three-pin XLR plugs are among the most common balanced audio connectors in use today, although there are a handful of brands that use a single, five-pin plug.

Four‑Pin XLR connector plugs: Externally identical to three-pin XLR connector plug, internally four-pin XLRs provide separate ‘+’ and ‘–‘ signals for both the left and right channels.

RSA connector plugs: RSA connector plugs, named in honor of Ray Samuels Audio, are sometimes found on small, portable, balanced output headphone amplifiers. RSA connector plugs essentially function like miniaturized 4-pin XLR connectors. Interestingly “RSA connectors” were developed by the firm Kobiconn Connector for use in certain types of camera connections, but Ray Samuels was the first to use Kobiconn Connector as a balanced audio connector in compact, portable amplifiers.

Tiny four-pin RSA/Kobiconn plugs support balanced audio connections for devices where space is at a premium.

3.5mm, four‑conductor, mini‑jack plugs: A handful of manufacturers have offered amplifier and headphone cables that provide balanced output connections through comparatively uncommon, four-conductor (or ‘four ring’) 3.5mm mini-jack plugs (where the conductors are labelled Tip, Ring, Ring, and Sleeve).

2.5mm, four‑conductor, connector plugs: Yet another means of providing balanced output connections is via a comparatively new-to-the-market four-conductor (or ‘four ring’) 2.5mm plug. This plug is the chosen balanced-output connector for use with the popular Astell & Kern AK240 portable digital music player/headphone amp.

Hybrid Headphone & Earphone Designs

Headphone and earphone makers, as well as the team at The Absolute Sound, use the descriptor ‘hybrid’ to indicate that the product in question uses a mixed (or ‘hybrid’) combination of technologies. One good example would be the recently released oBravo HAMT-3 Mk II headphone, which employs the hybrid combination of the dynamic-type mid/ bass driver and a Heil air motion transformer-type mid/high-frequency driver. Another good example would be the PSB M4U 4 universal-fit earphone, which employs the hybrid combination of a dynamic mid/bass driver and a balanced armature-type mid/high-frequency driver.

Final Audio Design’s Sonorous VI headphone looks conventional enough, but it features a hybrid dynamic/balanced armature-type driver array.

Noise‑Cancelling Headphones & Earphones

The term ‘noise-cancelling’ as applied to headphones or earphones means exactly what it says: namely, that the headphones/earphones provide active circuitry that detects external noise and then applies (to the best extent possible) an equal and opposite signal designed to cancel out the noise. For this reason, some designers (and marketers) prefer the term ‘active noise-cancelling’.

PSB’s M4U 8 is one of the very few active noise-cancelling headphones that manages to offer serious, audiophile-grade sound quality.

Noise‑Isolating Headphones & Earphones

Recognizing that active noise cancelling headphone and earphones can potentially create scenarios where the intended sonic ‘cure’ (active noise-cancellation) turns out to be worse than the sonic disease (noise), some designers have instead chosen to work on designs that use purely passive means of isolation or blocking out external noise. Generally, these passive designs are called ‘noise isolating’ (as opposed to ‘noise-cancelling’) headphones or earphones.

On‑Ear Headphones

Unlike circumaural (around-the-ear) headphones, on-ear headphones feature comparatively small ear cups with ear pads designed to rest upon, rather than to surround, the wearer’s ears.

On-ear headphones like the Klipsch Reference On-Ear have smaller ear cups and ear pads than equivalent circumaural headphones.

Open‑Back Headphones

Open-back headphones feature ear cups that, by design, are open both on their front (that is, ear-facing) sides and on their back sides (so that there is virtually nothing—apart from protective grilles—but open air behind the rear sides of the headphone drivers. In many respects open-back headphones are analogous to dipolar loudspeakers in that they have rigid perimeter frames, or in this case ear cup housings, with no sealed enclosures behind the drive units at all.

For self-evident reasons open-back headphones offer little if any isolation from external noise. However, there is much debate on whether open-back or closed-back designs offer superior overall driver performance and sound quality.

Planar Magnetic Drivers

The loudspeaker manufacturer Magnepan first pioneered planar magnetic drivers and holds (or once held) many of the core patents on the technology. Therefore, today’s modern planar magnetic headphones could, in a sense, be regarded as ‘Magnepans writ small’. In planar magnetic drivers, the diaphragm consists of a very thin but strong membranes on whose surfaces are found conductive circuit traces typically arrayed in very precisely dimensioned serpentine patterns, with the conductive traces are spread over the entire radiating surface of the diaphragm. Many manufacturers use some form of Mylar-like material for their diaphragms, but at least one manufacturer (HiFiMAN) is using a radically thin, low mass ‘nano-material’ diaphragm.

Then, placed in close proximity to the diaphragm there is a precisely aligned grid or array of powerful magnets with deliberate open-air spaces between the magnets to allow sound waves to pass through. Some designers favor the concept of having magnet arrays positioned on both the front and rear sides of the driver diaphragm, while others favor having an array on one side only—usually the side facing away from the listener’s ears. Either way, as musical signals are applied to the conductive traces on the diaphragm, the diaphragm is attracted to and/or repelled from the magnet array(s), thus producing sound.

The planar magnetic drivers used in the Abyss AB-1266 TC are considered to be among the most revealing of any headphone produced today.

Ribbon Drivers

Ribbon drivers could be considered a specialized-case version of planar magnetic drivers, but with one critically important difference. In a ribbon driver, the entire diaphragm is made of conductive, thin-film, metal material, so that in a very real sense the diaphragm is—to borrow dynamic driver terminology—its own voice coil. In most cases the ribbon driver diaphragm will be corrugated or ‘pleated’ and then suspended in the presence of very strong magnetic field. As musical signals are passed through the ribbon diaphragm/conductor, the diaphragm interacts with the surrounding magnetic field, moving fore and aft to produce sound.

Signal Cables

As is true in full-size, loudspeaker-based audio systems, headphone/earphone-based systems can be and typically are very sensitive to the quality of the signal-bearing cables in use. If you have any doubts as to whether cable substitutions can influence sound quality, let us assure you cables can impact sound in quite audible and obvious ways (and no, you don’t need to be a ‘golden ear’ to hear their effects).

We haven’t the space to go into cable technologies at this time but suffice it to say that it is worth seeking out headphones and earphones that either ship with very high-quality signal cables in the first place, or for which high-quality, third-party, aftermarket cables are available. Over time, you may discover—as we have—that judicious cable changes can help unlock hidden layers of performance in your favorite transducers.

Some pundits say wire substitution can’t possibly make an audible difference, but bluntly they’re wrong. You can easily prove this point by visiting a good headphone shop, trying some cable substitutions, listening carefully, and then drawing your own conclusions.

It is also important to recognize that most headphone/earphone failures in the field are attributable to cable failures. The point is that it is simpler and cheaper to replace a set of signal cables than to have to go shopping for entirely new headphones or earphones.

In addition, in a desktop personal audio application, different USB cables can have marked changes on the performance of a DAC.

Supra‑aural Headphones

Although you might rarely if ever hear this phrase in common usage, the term ‘supra-aural headphones’ is the formally correct way to say, ‘on-ear headphones’.

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