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Glossary

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Welcome to Sound On Sound's indispensible, regularly updated, explanations of technical terms from the fields of Recording, Audio Production, Music Technology, MIDI, Music Software, Audio Plug-ins, Mac and PC Computing, Live Sound, Acoustics, Electronics and more...

If we do not explain a particular term below, please email glossary@soundonsound.com and we will add it to our next update.

Last updated: 04/08/20

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Daisy Chain

An arrangement of sharing a common data signal between multiple devices. A ‘daisy chain’ is created by connecting the appropriate output (or through) port of one device to the input of the next. This configuration is often used for connecting multiple MIDI instruments together: the MIDI Out of the master device is connected to the MIDI In of the first slave, then the MIDI Thru of the first slave is connected to the MIDI In of the second slave, and so on... A similar arrangement is often used to share a master word clock sample synchronising signal between digital devices.

Damping

The control of a resonant device. In the context of reverberation, damping refers to the rate at which the reverberant energy is absorbed by the various surfaces in the environment. In the context of a loudspeaker it relates to the cabinet design and internal acoustic absorbers.

DANTE

A form of audio-over-IP (layer 3) created by Australian company Audinate in 2006. DANTE is an abbreviation of 'Digital Audio Network Through Ethernet'.

DAT

An abbreviation of Digital Audio Tape, but often used to refer to DAT recorders (more correctly known as R-DAT because they use a rotating head similar to a video recorder). Digital recorders using fixed or stationary heads (such as DCC) are known as S-DAT machines.

Data

Information stored and used by a computer.

DAW — Digital Audio Workstation

A term first used in the 1980s to describe early ‘tapeless’ recording/sampling machines like the Fairlight and Synclavier. Nowadays, DAW is more commonly used to describe Audio+MIDI ‘virtual studio’ software programs such as Cubase, Logic Pro, Digital Performer, Studio One and such-like. Essentially elaborate software running on a bespoke or generic computer platform which is designed to replicate the processes involved in recording, replaying, mixing and processing real or virtual audio signals. Many modern DAWs incorporate MIDI sequencing facilities as well as audio manipulation, a range of effects and sound generation.

dB / deciBel

The deciBel (dB) is a method of expressing the ratio between two quantities in a logarithmic fashion. Used when describing audio signal amplitudes because the logarithmic nature matches the logarithmic character of the human sense of hearing. The dB is used when comparing one signal level against another (such as the input and output levels of an amplifier or filter). When the two signal amplitudes are the same, the decibel value is 0dB. If one signal has twice the amplitude of the other the decibel value is +6dB, and if half the size it is -6dB.

When one signal is being compared to a standard reference level the term is supplemented with a suffix letter representing the specific reference. 0dBu implies a reference voltage of 0.775V rms, while 0dBV relates a reference voltage of 1.0V rms. The two most common standard audio level references are +4dBu (1.223V rms) and -10dBV (0.316V rms). The actual level difference between these is close to 12dB.

The term dBm is also sometimes encountered, and this relates to an amount of power rather than a voltage, specifically 1mW dissipated into 600 Ohms (which happens to generate a voltage of 0.775V rms). When discussing acoustic sound levels, 0dB SPL (sound pressure level) is the typical threshold of human hearing at 1kHz.

dB/Octave

A means of measuring the slope or steepness of a filter. The gentlest audio filter is typically 6dB/Octave (also called a first-order slope). Higher values indicate sharper filter slopes. 24dB/octave (fourth order) is the steepest normally found in analogue audio applications.

DBX

A manufacturer of audio processing equipment, most notably compressors and tape noise reduction systems. The DBX NR systems were commercial encode/decode analogue noise-reduction processors intended for consumer and semi-pro tape recording. Different models varied in complexity, but essentially DBX compressed the audio signals during recording and expanded them by an identical amount on playback.

DC

Direct Current. The form of electrical current supplied by batteries and the power supplies inside electrical equipment. The current flows in one direction only.

DC-Offset

Audio signals are conveyed electrically as an 'alternating current' or 'AC' signal. This might typically result in a signal voltage that varies, for example, between +3 Volts and -3 Volts, with a waveform that is more or less symmetrical about the 0V line. However, there are circumstances — often, but not always, as the result of a fault condition — where instead of alternating equally above and below zero volts, the signal voltage is offset, so it might now vary between, say, +4V and -2V. In this example it would have a DC-Offset of +1 Volt.

DC-Offsets are generally considered a bad thing, as they can result in audible clicks when editing the audio material, they can result in premature asymmetrical clipping (eg, postive peaks clipping before negative peaks), they can confuse level metering systems, and they can even cause damage to loudspeakers and headphones in some specific circumstances. 

As the DC-offset 'signal' effectively has a frequency of 0Hz, a DC-Offset can be removed with a high-pass filter set to a few Hertz (typically 3 or 5Hz, but anything with a turnover below 20Hz would get the job done).

DCA

Digitally Controlled Amplifier. The digital equivalent of a VCA often found in digital synthesisers and mixing consoles.

DCA Group

See VCA Group

DCC

A stationary-head digital recorder format developed by Philips, using a bespoke cassette medium similar in size and format to Compact Cassettes. It used an MPEG data reduction system to reduce the amount of data that needs to be stored.

DCO

Digitally Controlled Oscillator. Used in digitally-controlled synthesizers.

DC — Direct Current

The form of electrical current supplied by batteries and the power supplies inside electrical equipment. The current flows in one direction only.

DDL

An abbreviation of Digital Delay Line, used to create simple delay-based audio effects.

DDP

Disc Description Protocol. A data description format used for specifying the content of optical discs including CD, and used almost universally now for the delivery of disc masters to duplication houses. A DDP file contains four elements: the Audio image (.DAT); the DDP identifier (DDPID), the DDP Stream Descriptor (DDPMS); and a subcode descriptor (PQDESCR). Often an extra text file is also included with track titles and timing data. Many DAWs and audio editing programs can now create DDP files.

De-emphasis

A system which restores the spectral balance to correct for pre-emphasis.

De-esser

A device for reducing the effect of sibilance in vocal signals.

De-Oxidising Compound

A substance formulated to remove oxides from electrical contacts. (cf. Contact Cleaner)

Decay

The progressive reduction in amplitude of a sound or electrical signal over time, eg. The reverb decay of a room. In the context of an ADSR envelope shaper, the Decay phase starts as soon as the Attack phase has reached its maximum level.

Decca Tree

A form of ‘spaced microphone’ arrangement in which three microphone capsules (usually, but not always, with omnidirectional polar patterns) are placed in a large triangular array roughly two metres wide, with the central microphone one metre further forward. Sounds approaching from different directions arrive at each capsule at different times and with slightly different levels, and these timing and level differences are used to convey the directional information in the recording. The timing differences between channels can result in unwanted colouration if they are combined to produce a mono mix.

Decibel

— see dB

Decoupler (also isolator)

A device intended to prevent the transmission of physical vibration over a specific frequency range, such as a rubber or foam block.

Defragment

The process of rearranging the files on a hard disk so that all the files are as contiguous as possible, and that the remaining free space is also contiguous.

Delay

The time between a sound or control signal being generated and it auditioned or taking effect, measured in seconds. Often referred to as latency in the context of computer audio interfaces.

Desk

An alternative term for mixer (See also console).

Detent

One or more physical click-stops which can be felt when a rotary control is moved. Typically used to identify the centre of a control such as a pan or EQ cut/boost knob, or to give the impression of preset positions on a gain control.

DI

An abbreviation for ‘Direct Instrument’ or ‘Direct Inject’ - the two terms being used interchangeably. Used when an electrical sound source (eg electric guitar, bass or keyboard) is connected directly into an audio chain, rather than captured with a microphone in front of a amp/loudspeaker.

DI Box

Direct Injection, or Direct Instrument Box. A device which accepts the signal input from a guitar, bass, or keyboard and conditions it to conform to the requirements of a microphone signal at the output. The output is a mic-level, balanced signal with a low source impedance, capable of driving long mic cables. There is usually a facility to break the ground continuity between mic cable and source to avoid unwanted ground loop noises. Both active and passive versions are available, the former requiring power from internal batteries or phantom power via the mic cable. Active DI boxes generally have higher input impedances than passive types and are generally considered to sound better.

Diaphragm

the movable membrane in a microphone capsule which responds mechanically to variations in the pressure or pressure gradient of sound waves. The mechanical diaphragm vibrations are converted into an electrical signal usually through electromagnetic or electrostatic techniques such as ribbon, moving coil, capacitor or electret devices.

Digital (cf. Analogue)

A means of representing information (eg audio or video signals) in the form of binary codes comprising strings of 1s and 0s, or their electrical or physical equivalents. Digital audio circuitry uses discrete voltages or currents to represent the audio signal at specific moments in time (samples). A properly engineered digital system has infinite resolution, the same as an analogue system, but the audio bandwidth is restricted by the sample rate, and the signal-noise ratio (or dynamic range) is restricted by the word-length.

Digital Delay

A digital processor that generates delay and echo effects.

Digital Reverberator

A digital processor which simulates acoustic reverberation.

DIN Connector

A consumer multi-pin connection format used for vintage microphones, some consumer audio equipment, and MIDI cabling. Various pin configurations are available.

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