Synth Glossary

The ultimate glossary of synthesizer terms, this guide is an A-to-Z reference of everything you need to know to make electronic music: mixing + production techniques, effect processing tips and tricks, modular synth terminology, and more.

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A filter specification that refers to the steepness of the cutoff frequency slope. A 'pole' in filter design indicates a 6dB per octave attenuation. Thus, a 2-pole filter has a gentle 12dB/octave slope, and a 4-pole filter provides a steeper 24dB/octave roll-off. Sonically, 2-pole filters are commonly referred to as "smooth-sounding", while 4-pole filters have a more dramatic effect. Hypothetically, a filter may have any number of poles, though 2-pole and 4-pole topologies are most common.

see also: FILTER



A type of digital audio connection protocol, originally designed for expanding the number of I/O on a recording system via an optical (Lightpipe) cable connection. It emerged in 1992 with the release of Alesis Digital Audio Tape, which aimed to present a budget-friendly multitrack recording system. Each ADAT connection can carry up to 8 channels of uncompressed digital audio (24 bit, 48 kHz) in one direction.

Additive Synthesis

A synthesis technique that builds complex waveforms by combining a large number of sine waves with individually variable frequencies and amplitudes; often described in opposition to subtractive synthesis.



An acronym for the four stages of the most common type of synthesizer envelope: Attack, Decay, Sustain, and Release. Attack, Decay, and Release parameters determine the duration of their respective stages. The Sustain parameter is used to set the amplitude level of the envelope after the decay stage if the initiating key is still pressed (in the case of keyboard synthesizers) or the incoming Gate signal is still high (in the case of modular synthesizers).

see also: ENVELOPE


Also known as AES3, this is a standard for transferring digital audio, jointly developed by the Audio Engineering Society and European Broadcasting Union in the 1980s. Several connection types are employed within the standard, including RCA, TOSLINK, and XLR.


A continuous control message or signal derived from physical pressure applied to a MIDI or CV controller's key after it has been pressed. In the MIDI protocol, Aftertouch is commonly associated with CC numbers 2 (also Breath Controller) and 4 (also Foot Controller). Aftertouch may be monophonic (aka "channel pressure" or "channel aftertouch", in which a single key's pressure is detected and transmitted for all voices on a single MIDI channel), or polyphonic ("poly aftertouch", in which separate aftertouch messages are provided for each depressed key).

Algorithm (Effect Processing)

A distinct effect type within a category of effects in a multi-effect processor (for instance, a single multi-effect processor may contain several distinct distortion algorithms, several delay algorithms, etc). This term may also refer to a more complex signal processing structure in digital effects systems such as various Eventide multi-effect units. In this case, it describes several simpler processing elements being combined and interlinked together to form a more complex effect.

Algorithm (FM Synthesis)

A defined routing configuration between various operators in an FM synthesizer; historically, FM algorithms were established as pre-set configurations by the manufacturer, but present-day designs commonly allow the user to construct and save their own algorithms as well.

see also: FM SYNTHESIS


A term used in digital audio to describe an effect (or specific audio artifacts) that can occur during the analog-digital-analog conversion processes when a signal contains frequency ranges too high to be faithfully reconstructed at the system's sampling rate. According to the Nyquist theorem, an analog signal can be reconstructed digitally without any peceptible loss of resolution if the rate at which it is sampled is at least twice as high as the highest frequency in that signal. Although aliasing is largely undesirable, it can be exploited for aesthetic purposes as an audio effect.

see also: SAMPLE RATE


A circuit or a device that alters the amplitude of a signal. In the context of guitars, PA systems, or studio monitors, Amplifiers are used to significantly increase the amplitude of a signal in order to drive speakers; in synthesizers, studio consoles, and compressors, "Amplifier" may also refer to a VCA, or Voltage-Controlled Amplifier, which is commonly used to impart continuous dynamic control on signals.



An electrical signal’s voltage range; in synthesis, this often relates to a sound's volume, or the intensity of modulation. You can think of amplitude as the height of a waveform—the greater the waveform's voltage range, the greater its amplitude and the louder the sound, or the greater the intensity of its effect on another module.

Amplitude Modulation (AM)

A synthesis technique in which the amplitude of a given signal is continuously modulated by a separate signal source. At low modulation frequencies, this can produce a "tremolo"-like effect; at high frequencies, it can result in the creation of focused, yet complex audio spectra.


A circuit topology in which sounds are generated or manipulated in the form of continuously fluctuating voltages; compared to digital, in which sounds are represented as code and eventually translated into analog signals that can be sent to speakers.

see also: DIGITAL

Analog Shift Register (ASR)

A type of synthesizer module comprising multiple cascaded sample-and-holds interconnected in series. Once triggered, an input signal is sampled, and the sampled value is passed to the first output. With the next trigger, the signal is sampled again, the new value is passed to the first output, while the previous value is shifted to the next output, and so forth. First commercially presented in the Serge Modular system.

Analog to Digital Converter (ADC)

A circuit/chip/device that translates continuously variable analog signals into their equivalent digital representations.

Aperiodic Waveform

A waveform that doesn't repeat the same shape with every cycle (as opposed to periodic waveform). The great majority of natural sounds are aperiodic, while most common synthesizer waveforms (Saw, Sine, Triangle, Square) are periodic.


An acronym for a simple two-stage modulation envelope: Attack, Release. The Attack parameter describes how long it takes for the envelope to reach its peak, while the Release parameter specifies the time it takes to return to zero. Typically, AR envelopes imply the presence of a Sustain stage between the Attack and Release stages, which is held high for as long as the incoming gate is high (in the case of modular synthesizers), or for as long as the initiating key press continues (in the case of keyboard synthesizers).


A feature common to self-contained synthersizers and MIDI controllers which creates a repeating rhythmic pattern of notes based on an input note or chord. It is often used to turn played chords into arpeggios—musical ideas based on a specific set of notes being played one-by-one rather than all together.

Attack (Compression)

In compressors, the Attack parameter the length of time it take for the full compression ratio to be reached after incoming audio breaches the compression threshold.

see also: COMPRESSOR

Attack (Envelope Stage)

In synthesizers, Attack is the first stage of an envelope, which establishes the length of time it takes for an envelope to reach its peak voltage after the initiating key or gate is received.

see also: ENVELOPE


A tool used to decrease the amplitude of a signal, via the process of Attenuation.

see also: AMPLITUDE

Auxiliary (Aux)

An audio port that is supplementary to the main I/O. In consumer audio, a 3.5mm stereo connector/socket or pair of RCA connectors are commonly implemented, while pro-audio equipment usually uses 1/4" ports. "Aux" can also refer to a 1/8" TRS-to-TRS cable.



A term used to describe a form of connection that can be applied to both cables and equipment I/O. In an unbalanced connection, a cable carries only a signal, and a ground reference voltage. In a balanced connection, a cable carries a ground voltage, a signal, and a phase-inverted copy of the signal. The two copies of the signal can be compared at the destination stage in order to remove unwanted noise from the signal, significantly aiding in signal integrity.

The most common balanced cable types are 1/4" TRS cables and XLR cables. Professional recording equipment, microphones, and some high-end electronic musical instruments employ balanced outputs.

see also: UNBALANCED


A patch cable/signal connector format used in certain kinds of analog modular synthesizers such as Buchla, Serge, Synton, and Ciat-Lonbarde. Banana cables are unshielded, use a single conductor, and use 4mm plugs that usually can be stacked onto each other.


A limited range of frequencies in an audio signal.

Band Pass Filter (BPF)

A filter that only passes a limited range of audio frequencies, rejecting everything below and above the specified band.

see also: FILTER

Band Reject Filter

see also: NOTCH FILTER


The width of a frequency band from its upper to lower limits, measured in Hertz (Hz).


A collection of presets/programs/sounds on electronic musical instruments such as synthesizers, drum machines, and samplers. Often, program memory in such devices is divided into some number of distinct Banks, with a set number of Programs within each Bank.

Bantam (TT)

A 0.173" balanced signal connector/socket commonly used in professional audio patch bays. Bantam and TT are trademarked names.


A frequency range roughly in the range 28-400 Hz, in the lower range of human hearing.


Describes a signal that fluctuates between positive and negative values. Described in opposition to Unipolar signals, which contain exclusively positive or negative voltages.

Bit Depth

A measurement of amplitude resolution in digital audio systems or recordings, where the number of bits determines the number of potential amplitude values that a single sample can represent. Ultimately has a significant impact on the sound quality of digital audio and its potential dynamic range.

see also: SAMPLE RATE


A digital audio distortion effect based on decreasing bit depth of a signal, thereby significantly reducing its amplitude resolution and overall sound quality.

Read more in Weird FX: Bitcrushers

see also: BIT DEPTH


A specific subset of multitimbral synthesizer which can load and play two presets/programs/"timbres" simultaneously. Often, Bi-timbral synthesizers allow for keyboard splits, layering of two sounds, or for a mix of local (via built-in playing surface/keyboard) and remote (via external MIDI) control for each timbre, respectively.



A stereo microphone technique where two microphones with bi-directional polar patterns are placed in close proximity to each other along the vertical axis, and angled at 90 degrees with respect to one another.

Boost (Guitar Effect)

An effect that increases the volume of the signal without changing the tone.

Boundary / PZM Microphone

A special kind of condenser microphone based on the boundary effect phenomenon. Flat and wide, PZM mics look very different from other microphones. They work best when placed flush on a flat surface, and often are used on conference room tables and in theaters to amplify or record the entire room.


Beats per minute, often used as a measurement of a song's overall tempo—ultimately translating to a sense of the song's underlying level of energy/momentum.

Brown(ian) Noise

A type of noise that follows Brownian motion, where the fluctuations in signal from one moment to another are random. In practice, it is a "darker" sounding noise than more common colors (White or Pink), since its spectral density decreases as the frequency increases.


Bucket Brigade Device (BBD)

An analog delay line, where a stored signal is moved along a line of capacitors connected in series, one step per clock cycle. The process is compared to a bucket of water being passed along a line of people. Eventually, BBDs were encapsulated in dedicated IC chips; today, BBDs are a common part of analog delay, chorus, and flanger effects.

Buffer (Guitar Effects)

A device designed to restore the high-frequency content in a guitar signal by addressing the accumulated capacitance that emerges in long effects pedal chains, or when long cables are used. A buffer is also present in many guitar pedals as a way to transform a high-impedance guitar signal into a low impedance signal favored by the circuits in stompboxes.

Buffered Bypass

A specific cost-effective circuit design found in many effects pedals where the guitar's signal always passes through the buffer stage regardless of whether the processing is engaged or not. Some would claim that this can be detrimental to the integrity of the instrument's tone, but the jury's out on whether that's true in all contexts. We see it as generally being useful, with some special exceptions.

see also: TRUE BYPASS

Buffered Multiple

In modular synthesizers, a buffered multiple is a powered signal splitter module which uses a buffer in order to minimize the voltage droop that can accompany passive signal splitting. This is especially useful in maintaining the integrity of control voltages meant to be applied to the pitch of a sound, such as the 1V/Oct control voltage outputs from a keyboard or sequencer.

see also: MULTIPLE


A switch commonly found on signal processing devices such as guitar pedals that effectively lets one shift between processed and unaffected sound.



A heart-shaped microphone polar pattern most sensitive to the sounds in front of the microphone, and least responsive to the sounds coming from the rear of the capsule. Commonly used in situations where isolation from environmental sound is critical, or in situations where risk of microphone feedback is high.

Read more in Microphone Polar Patterns Explained



In many types of synthesis or audio processing, "carrier" describes a "primary" audio signal which is affected by some other "secondary" signal (the "Modulator"). The carrier/modulator terminology is commonly used to describe aspects of Frequency Modulation (FM), Phase Distortion (PD), and Phase Modulation (PM) synthesis methods, as well as processing techniques such as Ring Modulation, Frequency Shifting, and Vocoding.

see also: MODULATOR

Center Detent

A perceivable notch at the center position of certain potentiometers. This type of potentiometer is typically implemented for accuracy in parameter settings, and as sensory feedback to the user—usually indicating the center position for parameters which are considered "neutral" at their center (such as attenuverters, pan potentiometers, EQ frequency band level knobs, etc.).


An audio effect that emulates the detuning and timing inconsistencies that result from multiple instruments or voices playing/singing in unison with one another (a chorus, in the sense of a choir). Electronically, this effect is often achieved with a mid-range delay line whose time parameter is modulated by an LFO, often mixed together with the dry signal in order to create a sense of ever-shifting detuning.

Chroma Key

A visual special effect where two images are layered on top of one another based on their color hues. It is most commonly used to remove/replace one background with another, as in greenscreening.

see also: LUMA KEY

Circuit Bending

An experimental approach to DIY electronics, where a circuit of an existing sound-making device (usually cheap and used) is intuitively modified for the purpose of generating novel sounds and noises.


Often describes a pre-recorded segment of audio or MIDI data in a digital audio workstation or sequencing device. Clips often may be arranged/re-arranged in order to create a structured piece of music.


A distortion of an audio signal that occurs as a result of that signal being amplified beyond the maximum limit allowed by a given piece of equipment, resulting in a "squaring off" of the top and bottom edges of the signal's amplitude. This usually results in harsh audible distortion. Different clipping methods may be used for intentional audio effects.


A component or a device in a synthesizer that produces clean, precisely-timed pulses according to a set frequency. It serves as a time reference for synchronizing other parts of the system, i.e. sequencers, delay effects, etc. In modular and semi-modular synthesizers, analog clocks are usually repeating square wave signals; in MIDI-capable devices, a specialized digital MIDI clock signal may be used to synchronize multiple devices.

Clock Divider

In modular synthesizers, a clock divider is a common component that receives a clock pulse into its input and in response generates slower clock pulses at its output(s) that are related to musical timing conventions, i.e. /2, /4, /8. Useful for synchronizing multiple types of events at different time scales to a faster, unifying clock.

see also: CLOCK

Clock Multiplier

In modular synthesizers, a clock divider is a common component that receives a clock pulse into its input and in response generates faster clock pulses at its output(s) that are relevant to musical timing convention, i.e. x2, x4, x8. Typically used to synchronize events on multiple time scales from a single, slow-moving clock source.

see also: CLOCK

Coarse Tune

A control over the frequency/pitch in sound generators with a wide range, sacrificing exact level of accuracy. It is typically combined with a Fine Tune control, such that the Coarse Tune control gets you close to the desired pitch, while the Fine Tune control handles precise tuning. Note: in some instruments, a Coarse Tune control may simply be replaced by an octave/register switch.

see also: FINE TUNE

Comb Filtering

A type of sound filtering achieved by adding a slightly delayed version of the signal to itself. This results in phase cancelations and interferences that appear as distributed notches in the frequency spectrum of the signal (hence the name).


A low-level logic device common in modular synthesizers that compares an input signal and a reference voltage. If the input is higher than the reference voltage then the comparator output is high, if it is lower—the output is low. The reference voltage can be a static value or another signal.

Complex Oscillator

In modular synthesizers, a type of sound generator based on instruments introduced by Donald Buchla in the 1970s—specifically, the 208 Stored Program Sound Source/Music Easel and the later 259 Programmable Complex Waveform Generator. Typically, a Complex Oscillator is based on two interconnected oscillators: a principal oscillator with built-in waveshaping, and a modulation oscillator which is pre-wired to modulate the frequency, amplitude, and waveshaping of the principal oscillator in order to create a wide variety of timbres. The waveshaping section of a Complex Oscillator typically involves a wavefolder with multiple variable parameters.



A dynamic effect that boosts the volume of a signal and then reduces (or attenuates) the peaks of that signal beyond a certain threshold, preventing the sound from peaking or distorting. Often used to control dynamics, to add artificial sustain, or for special effects. Commonly available in studio rack format, guitar pedal format, and as virtual plugins.

Condenser Microphone

A microphone that works based on the principle of capacitance. The diaphragm is made out of a thin metal plate that sits atop another plate (backplate). Once a sound wave hits the diaphragm, it starts to move back and forth. The change in distance between the two plates effectively changes the electrical signal that passes through the circuit. Condenser microphones are active, and require external "Phantom" power to function, which is commonly supplied through the same cable that carries the audio signal. Condenser microphones are praised for their clarity and sensitivity, and as such are commonly used for record vocals, acoustic instruments, and other highly detailed sound sources.

Read more in Microphone Types Explained

Contact Microphone

Also known as piezo microphone, it is a special type of microphone based on the principle of piezoelectricity that senses mechanical vibrations in solid objects. Unlike other types of microphones, it is almost entirely non-responsive to sounds traveling through air. Commonly used by noise musicians to amplify objects, but also commonly part of amplification systems for acoustic guitars, violins, and other acoustic instruments.

Read more in Microphone Types Explained

Control Change (CC)

MIDI continuous control messages that are used for manipulating and automating parameters on MIDI-capable electronic musical instruments, software, and hardware. Up to 127 CC messages can be transmitted on each of the 16 MIDI channels, each with a typical resolution of 128 discrete steps. CCs are often generated by knobs, sliders, buttons, or other user interface elements, and can hypothetically be assigned to control any musical parameter—though how CCs are produced and interpreted is ultimately determined by the manufacturer of each specific MIDI-capable device.

Control Surface

A dedicated device for controlling software or hardware via a variety of methods such as analog voltage control, MIDI, and OSC protocols. Commonly, this refers to controllers purpose-built for providing mixer/console-like control of digital recording software (DAWs).

Control Voltage (CV)

A foundational concept in modular and semi-modular synthesizers, Control Voltages are signals (usually at relatively low frequences) which are carried over patch cables to allow one module to influence the behavior of another module over time. For instance, control voltages are produced by common modules such as LFOs, Envelopes, Sequencers and others; they may be used to influence a sound's pitch, timbre, loudness, and more. There are countless potential CV sources and applications beyond these listed few.

Read more in What is CV/Gate?


A device used to convert one type of signal/message into another, typically used in process which require communication between analog and digital domains. In Pro Audio applications, a converter may refer to a device which performs analog-to-digital or digital-to-analog conversion of audio signals; in synthesis, a MIDI to CV converter, for instance, converts digital MIDI information into appropriate corresponding control voltages.


A digital signal processing technique that uses recorded samples of physical environments and objects to create highly realistic digital simulations of them. Particularly, it is commonly used for reverb effects, as well as simulators of amplifiers, cabinets, and other analog equipment.


A device which allows you to use a single knob or slider to continuously fade between two distinct signals. Commonly a feature of DJ mixers; also commonly part of mixers or control voltage processors on modular synthesizers.


A specific type of filter circuit that splits an audio signal into two or more frequency ranges, typically so that the signals may then sent separately to individual loudspeaker drivers optimized for that particular range. May also be used to send different frequency ranges of a sound to different effect processes.

Crystals (Audio Effect)

A powerful audio effect, originally developed as an algorithm for the H3000 Harmonizer by Eventide, that combines stereo pitch-shifting and delay with reverse functionality. Now commonly emulated in pitch shifting delay effects.

Read more in Weird FX: Pitch Shifting Delays


The frequency at which a filter begins to take effect; the point beyond which frequency content is attenuated.

see also: FILTER

CV to MIDI Converter

A device which converts control voltages from a modular or semi-modular synthesizer into MIDI data, allowing modular synthesizers to provide control and timing information to MIDI-capable instruments or computers.

Read more in Creative Control Strategies: CV to MIDI



One complete vibration of a sound or periodic waveform. The pitch of sound waves and rate of LFOs is measured in cycles, using Hertz (Hz) as a unit of measurement. One complete cycle per second is equal to 1Hz; one thousand complete cycles per second is 1kHz (kilohertz). As a frame of reference, the range of human pitch perception ranges from roughly 20Hz to 20kHz.



A controller that used an infrared sensor to turn the performer's hand movements into a signal for controlling synthesizer parameters. Originally, the D-Beam was a standalone unit developed by Interactive Light, and later the technology and concept was purchased and trademarked by the Roland Corporation, who implemented it in a variety of their instruments starting with the MC-505 groovebox.

Daisy Chain

To connect a group of devices together in a series.


A dynamic audio processor designed specifically for the removal or reduction of harsh sibilant consonant sounds in audio signals, like "s", "z", and "sh". De-essing may appear as a function of a compressor, or a multi-band compressor.

Decay (Envelope Stage)

An envelope stage that defines the length of time it takes to go from previous stage to the next one. In ADSR envelopes it describes the duration between the end of the Attack stage and Sustain stage; in AD envelopes, it describes the duration between the end of the Attack stage and the envelope's return to 0V.

see also: ENVELOPE

Decibel (dB)

A unit of measurement used to express the loudness of sounds.


An elemental preset or settings state on an electronic musical instrument. Usually serves as a starting point for creating new sounds/effects. May also be referred to as an "initialized" state.

Delay (Audio Effect)

An echo-like effect. In digital delays, an input signal is continuously recorded, stored in a buffer, and then played back later. The delay time length is commonly expressed either in milliseconds or musical note units, and the number of repeats is specified by a parameter called "feedback." Analog delays perform a similar process using BBD (Bucket Brigade Device) integrated circuits, or by using magentic tape as the audio storage medium.

Delay (Envelope Stage)

In certain envelopes, a fixed amount of time between initial key onset or incoming gate and the beginning of the envelope's Attack stage.

see also: ENVELOPE


In synthesizers, detuning usually refers to the process of introducing a slight pitch difference between two or more oscillators (or synth voices) in order to create a chorus-like effect, adding thickness and motion to the sound.

see also: UNISON


Also known as the Direct Input box, it is an electronic device that is used for connecting high-impedance unbalanced output signals (i.e. guitar, synthesizer, etc., typically with a 1/4" output jack) to low-impedance balanced inputs of pro-audio equipment (i.e. audio interfaces, mixers, etc., typically with an XLR input jack).


A transducer that converts mechanical energy into an electric signal, and vice versa. It is an essential component in microphone and loudspeaker design, and typically it is made out of a thin membrane for which a number of materials can be used ranging from paper to metal.


A circuit topology in which sounds are generated or manipulated through the use of coded/programmed digital processes on a computer, processor, microcontroller, etc; as opposed to analog processes, in which sounds are represented by continuously fluctuating voltages which are generated/manipulated through circuitry comprised of discrete electronic components.

see also: ANALOG

Digital Audio Workstation (DAW)

A computer program such as Ableton Live, FL Studio, Pro Tools, Bitwig, Logic, etc. which is used to record, edit, arrange, modify, and mix audio. Often, DAWs also provide the ability to record, edit, and arrange MIDI data in order to control virtual instruments.

Digital Signal Processing (DSP)

A method of transforming an audio signal in a wide variety of ways via digital tools and algorithms.

Digital to Analog Converter (DAC)

A circuit/chip/device that translates digital representations of signals into corresponding analog fluctuating voltages.

Digitally Controller Oscillator (DCO)

An analog oscillator topology which uses digital circuitry to determine oscillator reset timing—translating to generally greater stability than more typical analog oscillators with comparator-controlled reset timing. DCOs became popular in the early 1980s with the advent of polyphonic analog synthesizers, solving tuning stability issues with older analog oscillator designs.


A type of electrical connector standardized by the Deutsches Institut für Normung in the 1970s. While there are a few types of DIN connectors, perhaps the most common is the circular DIN-5, a 5-pin connector commonly used for sending and receiving MIDI data.

DIN Sync (Sync24)

An analog protocol for synchronization of electronic musical instruments via a 5-pin DIN port, introduced in the 1980s by Roland Corporation.

Diode Ladder Filter

A filter design which employs a "diode ladder" in its core circuitry. This design was originally created by EMS for the VCS3 synthesizer, purportedly to avoid using Moog's patented Transistor Ladder Filter. Later, a similar design was famously implemented by Roland in their classic TB-303 bassline synthesizer.


A type of non-linear audio effect that can drastically alter sound's harmonic content, and amplitude. The term can be used to either describe an unwanted audio artifact, or intentionally aesthetic modification of sound. Commonly available in the form of guitar pedals.

Duophonic or Duophony

A synthesizer architecture capable of playing two pitches simultaneously, first introduced in analog synthesizers in the early 1970s. Typically, "duophonic" describes a two-note polyphonic synthesis structure with a single articulative structure for all included notes—in modern contexts, this is considered a subtype of Paraphony.

Read more in Synthesizer Polyphony—What Does It Mean?


Duty Cycle

see also: PULSE WIDTH


Relating to a sound's amplitude (loudness) fluctuations.

Dynamic Microphone

A type of microphone that operates on the principle of electromagnetic induction. A moving coil is affixed onto the rear side of the membrane, surrounded by a strong magnet. When sound waves start vibrating the membrane/coil, the difference in its position within the electromagnetic field is translated into a fluctuating electrical signal. Dynamic microphones are typically considerably less sensitive than condenser microphones, providing them greater isolation from environmental sounds and higher tolerance for particularly loud sounds.

Read more in Microphone Types Explained—and check out our a href="" target=newtab>Dynamic Microphone Buying Guide!

Dynamic Range

The difference between the softest and the loudest volume level that a musical instrument or an audio device is capable of producing. May also refer to the difference between the softest and loudest volume levels in an audio recording.


East Coast Synthesis

A term commonly used to refer to approaches to electronic instrument design inspired by concepts in Moog's earliest modular synthesizers. Typical definitions of this approach involve subtractive synthesis with rich oscillators and characterful filters, simple envelope generators, and keyboard-centric control. The term originated in the 1960s as a differentiator between conceptual approaches to synthesis, interaction, and user interface in the earliest commercial instruments created by Bob Moog (based in New York, on the East Coast of the US) and Don Buchla (based in California, on the West Coast of the US).

Read more in East Coast Synthesis vs. West Coast Synthesis



A general term used to describe any device, a section on a device, or a piece of software designed to process and alter sounds.


A term used by some synthesizer manufacturers to describe the Resonance of a filter.

see also: RESONANCE


A (usually) unipolar modulation signal that determines a change of a given parameter of a sound over time. Envelopes are typically one-shot modulation sources, which may be initiated by some discrete event—in keyboard synthesizers, this may be a keypress, though envelopes may also be triggered by sequencers, arpeggiators, or by gate/trigger/pulse signals in modular synthesizers. Envelopes typically provide variable controls for individual stages, which describe durations and voltage levels which define how the envelope changes over time. Common envelope stage types include Attack, Decay, Sustain, and Release, though in more complex envelopes, Delay and Hold stages may also be employed. Most typically, synthesizers include ADSR (Attack / Decay / Sustain / Release) or AD (Attack / Decay) envelopes, which are commonly hardwired to a synthesizer's filter and amplifier.

Envelope Filter

Sometimes called an auto-wah, an Envelope Filter is an effect that is created by combining an envelope follower with a filter in such a way that the cutoff frequency of the filter is modulated directly by the volume of the sound that is passed through the filter. This can create automated filter sweeps, quacking sounds, and all sorts of vocal-like sonic characteristics—think Jerry Garcia and '70s adult film soundtracks.

Envelope Follower

A circuit in a modular synthesizer which accepts incoming audio and produces a continuous voltage analogous to the incoming sound's loudness, which may be used as a modulation source for any parameter of the synthesizer. Commonly used to create dynamically-controlled synthesizer patches from microphones, acoustic instruments, drum machines, etc.

Equalizer (EQ)

A device that is used for altering the frequency balance of a signal by boosting or cutting selected frequencies, and/or frequency bands (groups of frequencies).


A modular synthesizer format established by Doepfer Musikelektronik in 1996, and since then picked up by a variety of other manufacturers. It is defined by the compact 3U and 1U sizes of modules, 3.5mm mono jacks for signal patching, a +/- 12V DC power bus distributed by either 10-pin or 16-pin ribbon cables, and 10V peak-to-peak audio signal range. It is by far the most popular and common modular synthesizer format to date, now used as a standard by hundreds of distinct synthesizer manufacturers, allowing users to create systems comprised of designs from many developers.

Read more in What is a Modular Synthesizer?

Expander (Dynamic Effect)

A dynamics processing effect used for increasing the dynamic range of a signal—it is the opposite effect of a compressor.

Expander (Hardware)

A device that works as an extension to the main unit. Common in the realm of Eurorack modular synthesizers, in which many modules may offer extended functionality when used in conjunction with an optional expander.

Expansion Board

An optional circuit board installed in a device to add additional sound presets or effects.

Expression Pedal

A foot pedal that is used to control various parameters on electronic musical instruments and sound processing devices. Expression pedal functionality is common to many synthesizers and guitar effect pedals.


Feedback (Audio Phenomenon)

Also known as the Larsen effect, Feedback is a tone that occurs when a system's output signal is returned back into its input. In live sound reinforcement, this is typically the result of a microphone picking up and amplifying the sound of a speaker to which it is connected, resulting in a loud, undesirable tone. Acoustic and electronic feedback are also commonly induced as part of various electronic music performance practices such as "No Input Mixing."

Feedback (Delay Effects)

A parameter that defines the amount of output signal sent back into the input. Also, occasionally it is called "Regeneration" or "Repeats".

Field Recorder

A portable audio recording device designed for capturing sounds outside of the recording studio, usually saving recorded sounds to internal memory or onto removable media such as an SD card.


A bi-directional microphone polar pattern that is equally sensitive to sounds coming from the front and the back, but rejects sounds coming from the sides. It is typical of, but not exclusive to ribbon microphones.

Read more in Microphone Polar Patterns Explained



A processor that removes certain frequencies and harmonics from a sound and allows others to pass through. A low-pass filter, for instance, only allows frequencies below its cutoff frequency to pass, resulting in low frequencies or low-pitched sounds coming through—creating a darkening effect. A high-pass filter, on the other hand, allows frequencies above its cutoff frequency to pass, making sounds appear more thin. Filters are used in a variety of devices, from Equalizers and Crossovers to guitar pedals and synthesizers, where they are commonly used to create drastic changes to sound over time.


Filter Bank

An array of filters that separates the input signal into individual frequency bands, often with individual volume controls for each constituent filter. Usually comprised of a lowpass filter, many bandpass filters, and a highpass filter. Filter banks were commonly used in early electronic music studios, and were part of early modular synthesizer systems made by Moog, Buchla, and Serge.

Read more in Weird FX: Fixed Filter Banks

Filter Slope

A filter design specification that describes the steepness of attenuation beyond the cutoff frequency. It is expressed in dB/octave (typically in increments of 6 dB/oct, according to the number of poles employed in the filter core).

see also: 2-POLE/4-POLE

Fine Tune

Common to modular synthesizer and keyboard synthesizer oscillators, Fine Tune is a precision control used for micro-adjustment of a sound source's frequency/pitch parameter. It is complementary to the Coarse Tune parameter, which is used for creating wider changes in pitch.

see also: COARSE TUNE


An audio effect created when a slightly delayed copy of an audio signal is mixed with the original, and the delay time parameter, usually in the range of 0.1ms to 20ms, is modulated by a low-frequency oscillator. In other words, it is a modulated comb filter. Commonly available in guitar pedal format.

FM Synthesis

Frequency Modulation Synthesis is an extensively-explored synthesis method, developed by John Chowning at CCRMA and first commercially explored by Yamaha in their DX-series synthesizers. In this style of FM Synthesis, digital "operators" (combinations of sine oscillators and amplifiers) are used to influence one another's phase at audio rates, resulting in the creation of complex timbres. Typically, FM synthesizers provide access to multiple Algorithms, which define signal paths by which multiple operators may influence one another. FM Synthesis gained popularity in the 1980s, and is notoriously complex/time consuming to program, given the vast number of variables involved in creating a sound.


A frequency band in a sound spectrum that resonates at great intensity, and determines the tonal characteristics of a particular vowel sound. May refer to a type of filter/filter bank intended to create vowel-like sounds.

Format Converter / Format Jumbler

A utility device used for interconnecting modular synthesizers of different formats which use different types of patch cables for signal connections, i.e. Serge and Eurorack, which use banana and 3.5mm jacks, respectively.


A number of vibrations per unit of time. Audio frequencies are expressed in Hz (cycles/second); a sound's frequency is directly related to our sense of pitch. That is to say, the higher the frequency, the higher the perceived pitch.

Frequency Modulation (FM)

A synthesis technique where the frequency of one oscillator is modulated at audio rate by another oscillator, effectively changing its timbre.

Frequency Shifter

An audio effect, in some ways similar to ring modulation, where all frequencies in a sound a shifted up or down by the same number of Hz—as opposed to pitch shifters, in which all frequencies are shifted by the same proportional amount. Often, this results in inharmonic sound structures similar to ring modulation.

Read more in Weird FX: Frequency Shifters


The frequency of a periodic waveform. The sound's overtones/harmonics usually occur at integer multiples of this frequency, and this frequency itself usually corresponds to what we perceive as a given sound's pitch.

see also: HARMONIC


A type of audio distortion effect that was discovered by the guitarist Grady Martin in early 1960s when he accidentally ran his guitar through a faulty mixer channel. He later recorded a song with that sound which he named "The Fuzz". The effect is known for its particularly "gritty", "raw", and "broken" sonic quality. Fuzz effects are now commonly achieved with commercial guitar effect pedals.



The amount of amplification applied to a signal at a specified part of a signal chain. Impacts a signal's loudness; in distortion-based effects, this typically directly relates to the intensity of the distortion applied to the incoming signal.

Gate (Audio Effect)

A dynamic audio effect that prevents sounds quieter than a set threshold from passing to the output. It can be viewed as an extreme version of downward expansion. Typically employed to remove noise floor in quiet passages of a recording or performance.

Gate (Synthesis)

In analog synthesizers, a modulation signal that has only two states (low and high), typically produced by devices like keyboards and sequencers, used to start/stop musical events. Unlike Triggers, the length of a Gate signal is typically variable, or arbitrarily definable.

Read more in What is CV/Gate?

see also: TRIGGER


A parameter in electronic musical instruments that determines the length of time it takes to transition from one note to another, creating a continuous glissando-like pitch effect. On some instruments, it is also called 'portamento'.


A musical term to describe a smooth continuous transition between notes.

Granular Synthesis

An approach to sound synthesis with a focus on microsonic events—generally sounds that are shorter than 0.1 seconds, but longer than 0.01 seconds. These microsounds are called "grains". Using a wide variety of methods, large quantities of sound "grains" can be combined into clouds, and clusters to create complex sonic timbres, and textures. Granular synthesis techniques often involve samples of recorded audio, however sampling is not a requisite part of granular synthesis.


A term initially introduced by the Roland Corporation during the marketing campaign for MC-303 in 1996, which since then has been commonly used to refer to music production hardware pieces that combine a sequencer, controller interface elements, and a sound engine (sampler, synth, drum machine) in one box.


Hard Clipping

A type of distortion effect where the output signal is limited to a set maximum amplitude level. If the input signal exceeds this maximum, the louder portion of the signal is clipped. A characteristic quality of this type of distortion is that it adds odd harmonics to the fundamental frequency of the input signal.

see also: CLIPPING

Hard Sync

A method of synchronizing one oscillator to another where the following oscillator's phase is reset each time the leading oscillator restarts its cycle, regardless of where it was itself in the cycle. Can result in everything from pitch tracking to striking timbral effects.

Read more in What is Oscillator Sync?

see also: SOFT SYNC


A wave in a frequency spectrum that is a positive integer multiple of the fundamental frequency.


Harmonic Tremolo

A special type of tremolo effect where an input signal is split into low and high frequency bands, which are then modulated by an LFO in an alternating pattern. Thus it rhythmically changes the frequency balance, and not the amplitude of the signal. A desirable effect among guitarists, it would seem.


An audio effect that duplicates an input signal, and allows the user to transpose a copy or multiple copies of the signal up and down to create musical harmonies. The term was initially introduced by Eventide with the release of the H910 Harmonizer.

Read more in A Brief History of Eventide


In digital and analog audio equipment, headroom is the difference between the typical signal level that a particular system is designed for, and the maximum signal level it can produce without distorting. The greater the headroom of a system, the greater its potential dynamic range.

High Pass Filter

A high-pass filter only allows frequencies above its cutoff frequency to pass untouched, and reduces the level of lower harmonics below the cutoff. This results in high frequencies or high-pitched sounds coming through, making sounds appear more thin. High-pass filters may appear as part of synthesizers, sound reinforcement equipment, or recording equipment.

see also: FILTER

Hold (Envelope Stage)

In some envelopes, it is a fixed amount of time added between one envelope stage, and the next. In some envelopes, this parameter is also called 'delay'

Horizontal Pitch (HP)

A unit of measure standardized by Eurocard rackmount systems, used to specify the horizontal width of rack-mounted electronic equipment. Horizontal Pitch is the unit of measurement used to specify the width of Eurorack-format synthesizer modules. 1HP equals 5.08mm.


Refers to a synthesizer architecture that combines both digital and analog circuity.


A highly directional microphone polar pattern. It is similar to cardioid's directional response shape but exhibits more sensitivity towards sound sources in front of it, much less to the sides, and a minor sensitivity lobe in the rear.

Read more in Microphone Polar Patterns Explained



An alternative standard for using voltage to control the pitch parameter in some synthesizers, historically employed by Korg and Yamaha. Unlike the common 1V/Octave standard, which uses a 1:1 correlation between the voltage and octave (a jump up or down an octave is exactly a 1-volt shift), Hz/V implies that a change in one octave corresponds to a fixed number of cycles per second.



Commonly shortened form of "inputs/outputs," referring to the cable connectivity on a given device.


A measure of resistance in a circuit towards an alternating current (such as an audio signal). It is measured in Ohms, and commonly represented by the "Z" symbol.

Impulse Response (IR)

A output signal produced in response to a short pulse signal (called an impulse) sent into a system or environment, used in order to store the sonic characteristics of that system or environment. It is commonly applied in convolution reverb technology, as well as amp and cabinet simulations. Often takes the form of a standard audio file.


Interface (Audio Interface)

A hardware device that facilitates interfacing between computers and audio equipment via digital-to-analog, analog-to-digital converters, and a combination of input and output ports. Often communicates with a host computer via USB, Thunderbolt, or other digital communication protocols.

Read more in Which Audio Interface is Right for You?—and check out our guide of the Best Audio Interfaces Under $500!



An alternative name for a port in electronic hardware that a cable connector or a plug attaches to.


A controller device that in its basic form features a short stick that generates control voltage or data by being moved along the X and Y axes. Common in gaming systems, lighting design, and other applications, joysticks can be used for expressive or gestural control in electronic musical instruments.


Karplus-Strong Synthesis

A type of physical modeling synthesis that uses a short delay line with high feedback settings and a filtering process in the delay feedback loop in order to replicate the sounds of vibrating strings.


Key Tracking

A feature in some synthesizers that allows one to use the control output of the keyboard as a modulation source for any number of available parameters. Commonly used in order to affect a filter's cutoff frequency to counteract changes in timbre/loudness as pitches increase and decrease.


The rail that stops the downward motion of the key on a keyboard instrument. Also commonly used to refer to the entire keyboard action, including the keys themselves.


A set of keys on a piano, organ, synthesizer, and many other musical instruments.



A term used in some multi-timbral synthesizers and workstations that refers to a complete timbre/voice that can be combined and played simultaneously with another voice to achieve a more complex sound.


An acronym for "Liquid Crystal Diode" or "Liquid Crystal Display"—a plasma-based display used in some instruments.


A term used to describe a (monophonic) synthesizer sound that is well-suited for playing melodic or soloistic passages.


Commonly, a parameter that corresponds to the volume or loudness of a signal.


A dynamic processor that limits a signal from exceeding a set amplitude threshold. Commonly implemented using a compressor with a compression ratio of greater than 10:1.

see also: COMPRESSOR

Line Level

A standardized strength of an audio signal. In fact, there are two standards for line-level signals: consumer audio (-10dBV), and professional audio (+4dBu)

Linear Arithmetic Synthesis

A sound synthesis method developed by Roland Corporation for the D-50 synthesizer. LA synthesis largely follows the strategies of traditional subtractive synthesis, yet it includes sampling. A voice in the LA synthesis method may be shaped by a transient attack from a sampled source blended with a classic analog sawtooth or pulse wave, and further combined with a looped single cycle waveform.


The most directional of microphone polar patterns, characterized by extreme sensitivity to sounds in front, and minor responsiveness to sounds approaching from the sides, and back. This polar pattern is very common among shotgun microphones.

Read more in Microphone Polar Patterns Explained



A family of synthesizer modules that allow you to establish rules and behaviors in a synth patch. Logic modules broadly include Boolean and analog logic (AND, OR, XOR, NAND, NOR, XNOR), comparators, sequential switches, and others.

Loop Switcher

A device comprised of an array of effects loops, coupled with footswitches for sending the signal into each loop. Commonly used in guitar effect pedal setups in order to maintain maximum signal integrity when certain pedals are not in use, or for performative signal routing changes.


A device that allows for real-time recording, overdubbing, and manipulating of audio signals. Commonly available in guitar pedal or desktop device format.


A function that restarts a sample as soon as it has finished, creating a continuous repeating sound. Often used to create single-performer layered compositions or soundscapes.

see also: LOOPER

Low Frequency Oscillator (LFO)

An oscillator that produces an output below the range of human hearing, and is used to impart cyclical modulation of desired parameters in synthesizers and other electronic musical instruments.

Low Pass Filter

A low-pass filter only allows frequencies below its cutoff frequency to pass untouched, and reduces the level of higher harmonics above the cutoff. This results in low frequencies or low-pitched sounds coming through, often used to darken brighter sounds. Low Pass Filters are a common part of keyboard and modular synthesizers, and are a key part of sound-shaping in Subtractive Synthesis.


Low Pass Gate (LPG)

A dynamics management module similar in function to a traditional VCA, originally developed by Donald Buchla for the 200 Series Electric Music Box and other instruments in the 1970s. Unlike a traditional VCA, a Low Pass Gate combines the qualities of a voltage-controlled amplifier and a non-resonant low-pass filter. This results in simultaneous coupled control of a sound's volume and brightness—an effect that naturally occurs in many acoustic instruments. Notably, traditional LPGs also use vactrols in their signal path, which impart a slight sluggishness and "buildup" in response to external control voltages, adding further nonlinear/organic qualities to their sound.


Luma Key

A visual effect similar to Chroma Keying, which alters the opacity of pixels in an image based on their brightness—typically used to create dynamic composites of multiple images.

see also: CHROMA KEY



A control element that is assigned to multiple parameters with individually set ranges. This allows for implementing complex modifications to a patch or preset with a single gesture.

Matrix Mixer

A special kind of signal mixer that allows routing multiple inputs to multiple outputs. Commonly, Matrix Mixers may feature either rows and columns of buttons for fixed level routing or knobs for variable level routing.


A capacity of a device to store data, which may include preset program data, sampled audio, and more.


To combine two or more data streams into one. The term "Merge" is commonly used in MIDI routing scenarios, in which two or more MIDI control sources need to be merged together in order to connect to a single MIDI destination.


A visual indicator of a signal level. May manifest as a single LED or lamp, a multi-segment LED display, a VU meter, etc.


An acronym for Musical Instrument Digital Interface, a communication protocol that allows electronic instruments and computers send musical performance information to one another. First introduced in 1983, MIDI is now a ubiquitous protocol common to most electronic musical instruments, computers, and more.

Read more in A Brief History of MIDI

MIDI Clock

A special type of MIDI message which conveys timing information that is used for synchronizing various MIDI-capable software and hardware devices.

MIDI Message

A formatted message within the MIDI protocol that consists of up to three bytes of data. e.g., MIDI Note-On message consists of channel number, note value, and velocity. MIDI messages may include note messages, control changes, program changes, and more.

MIDI Polyphonic Expression (MPE)

An extended specification to the standard MIDI protocol which adds extensive gestural control options. MPE works by allocating each note to its own MIDI channel, which enables extended per-note expressive potential through use of polyphonic pitch bend and CC mapping. MPE controllers are typically optimized to produce per-note pitch bend and CC messages through the use of a multidimensional playing interface in which each "key" or "pad" can detect strike velocity, release velocity, and can continuously track the player's finger position in the X (horizontal), Y (vertical), and Z (pressure) dimensions.

Read more in What is MPE?

MIDI to CV Converter

A device used to convert MIDI data into analogous streams of control voltages for use with modular or semi-modular synthesizers. MIDI to CV converters may be used to send pitch, gate, and velocity data from MIDI note messages, to convert Control Change messages into continuous control voltages, and more, as specified by the designer of each individual MIDI to CV converter.

Read more in Creative Control Strategies: MIDI to CV



A general term used to describe mid-range frequency bands, commonly for the purpose of equalization. This range typically corresponds to frequencies in the range between 500Hz and 2kHZ.

see also: EQUALIZER (EQ)


A device used for combining multiple audio signals into single, dual, or multiple output signals. It often includes additional features such as microphone preamplifiers, equalization tools, and occasionally effects. In modular synthesizers, DC-coupled mixers may also be used to combine multiple control voltages to route to a single or multiple destinations.

An approach to synthesis related to physical modeling, that uses mathematical descriptions of complex geometries and properties of real objects for sound creation. Commonly used for recreating the characteristics of resonators, modal synthesis may be approached by implementing a series of resonant bandpass filters in order to emulate the "modes" of a resonant, ringing object.



A circuit or a program that simulates the behavior and properties of another object or system, i.e. analog modeling, physical modeling, amp modeling, etc.

Modular Synthesizer

A synthesizer in which the different components, such as the oscillator, filter, VCA, VCF, etc. are separated into discrete modules, requiring the user to create interconnections between modules via patch cables in order to generate sound, and to determine how the instrument may be played. Commonly, modular synthesizers feature removable modules which may be swapped by the user in order to customize the instrument; however, this is not true of all modular synthesizers. The level of customization possible, both in terms of module selection and in terms of signal flow, leads many to value their flexibility when compared to synthesizers with a fixed internal signal path determined by the designer.

Read more in What is a Modular Synthesizer?

Modulation (Effect Processing)

Modulation Effects typically refer to effects in which some aspect of a sound's timbre changes over time in conjunction with an automated process. This may include effects such as chorus, vibrato, flangers, phasers, tremolo, and more.

Modulation (Synthesis)

The process of using a signal to vary the properties/behaviors of another signal, allowing the creation of dynamic behaviors in which sounds change in some way over time.

Modulation Matrix

A routing system for assigning modulation signals to modulation destinations. A common part of digital and hybrid self-contained synthesizers, which typically offer a fixed number of Modulation Matrix "slots" by which users may customize the internal signal routing of control signals within their instrument.


Generally, a signal used for varying the properties of another signal. In Frequency Modulation (FM), Phase Modulation (PM), Phase Distortion (PD), Ring Modulation, Frequency Shifting, Vocoding, and other specialized synthesis and effect types, it refers to the signal used to impart changes onto a Carrier signal.

see also: CARRIER


A component in a synthesizer that is assigned a specific function or a set of functions, e.g. oscillator, filter, amplifier, LFO, envelope, etc. In modular synthesizers, individual modules can commonly be swapped at will by the user; in self-contained, standalone instruments, the selection of modules is fixed, determined by the designer.

In a separate context, a Module may refer to an entire instrument/synthesizer, commonly in desktop/rackmount format, which is intended to be played by an external control source (such as a MIDI controller) or a computer.

Mono (Audio)

Describes an audio source or file with a single discrete audio channel, as opposed to Stereo or other multi-channel audio formats.

Monophonic (Synth)

A synthesizer voice structure that allows users to play only a single note at a time. Common among analog synthesizers, and often available as a polyphony mode in polyphonic analog, digital, and hybrid synthesizers, allowing users to choose to play only a single note at a time. Commonly used to create lead and bass tones.

Read more in Synthesizer Polyphony—What Does It Mean?

see also: POLYPHONIC

Multi-Band Compressor

An advanced form of compressor that allows for the independent management of signal dynamics at different frequency bands.


A sound processing device that hosts several types of effects, often with the ability to access multiple types of effects simultaneously. Commonly available in guitar pedal, desktop, and modular synthesizer formats.

Multi-Tap Delay

A rhythmic delay effect comprised of multiple delay lines set to different delay times. Multi-tap delays may provide individual timing and level controls for each delay tap, or may offer the user preset selections of taps, or may offer macro control of each tap's timing and level relative to one another.


A synthesizer module that copies a single input signal to multiple outputs, so that it can be sent to several destinations simultaneously.



Describes an electronic musical instrument that is capable of producing more than one sound or timbre simultaneously. Often used to create splits, layers, or simply to remotely control multiple distinct sounds simultaneously.


A recording technique that allows for the recording of separate audio streams on discrete tracks, which may later be independently edited, mixed, processed, or otherwise manipulated.


Noise (Recording)

An unwanted interference in a recorded audio signal that can be caused by a number of factors such as equipment self-noise, and environmental bleed.

Noise (Synthesis)

A number of non-periodic waveforms, each characterized by a distinct spectral balance. Examples include white noise, pink noise, brown noise, etc.

Noise Gate


Noise Generator

A device that generates one or more noise waveforms. Common in modular synthesizers, or as an internal component of self-contained synthesizers.


Notch Filter

A filter that passes most of the audio frequencies, except for the those that fall within the specified cutoff range. It is also known as a Band-Stop or a Band-Reject filter. The opposite of a Band Pass filter.

see also: FILTER

Nyquist Frequency (Folding Frequency)

A frequency in a digital audio system that is one half of its sampling rate; sounds beyond this frequency cannot be reproduced, and will result in aliasing.

see also: SAMPLE RATE



A musical interval that is double the frequency of the original pitch.


An audio effect that blends an input signal with a synthesized tone that is an octave below the pitch of the original. Occasionally, octavers will offer an octave up function, as well.


A microphone polar pattern characteristic of pressure microphones that equally picks up sounds from all directions.

Read more in Microphone Polar Patterns Explained


One Shot

A sound sample set to play only once (as opposed to a loop).

Open Sound Control (OSC)

A networking protocol for interconnecting and controlling synthesizers, computers, and other types of multimedia devices. Often used as an alternative to MIDI in applications such as Max/MSP, Pure Data, Supercollider, and others.


In FM Synthesis, an Operator is an oscillator with variable frequency and amplitude. Groups of Operators may be reconfigured into different "algorithms," altering their influence on one another.

see also: FM SYNTHESIS


A microphone technique for stereo recording developed by French national broadcast system Office de Radiodiffusion-Télévision Française, which employs two cardioid mics spread to a 110º angle, and spaced 17cm apart from each other. Unlike other stereo micing techniques, ORTF also provides good mono compatibility.


A component of a synthesizer or electronic instrument which produces periodic waveforms. Typically functions as a sound source which may be sculpted by other processes within the instrument, but may also be used to impart periodic changes on a signal.



An effect that occurs when the amplitude of an input signal exceeds the circuit's capacity to handle it, resulting in an increase of volume and harmonic content. In guitar effect processing, overdrive often refers to the sonic character of overdriving an amplifier; in a more contemporary context, "overdrive" often refers to a type of effect pedal/processor which imparts an amp-like distortion characteristic onto a sound.


see also: HARMONIC


Pad (Audio)

In electronic musical devices, PAD stands for Passive Attenuation Device, and implies attenuation of the signal by a fixed decibel value. Pads are commonly found on microphones, direct boxes, microphone preamplifiers, recording consoles, mixers, and more.

Pad (Synthesis)

A synthesized sound characterized by a long evolving tone, and gentle attack. Usually creates a sense of harmonic background to a track.


A control that determines the positioning of sounds at particular locations within the stereo field. Also applies to multi-channel spatialization systems.


The act of positioning a sound at a particular location within the stereo field, or other multi-channel audio spatialization environment. Panning may be static, or may be dynamically controlled.


A technique that involves processing the same sound simultaneously through separate, unrelated audio effect chains, as opposed to Series signal routing.

see also: SERIES

Parallel Compression

A dynamics processing technique that employs blending a heavily compressed signal with an unprocessed version of that signal.


An element in an electronic musical device that directly affects a particular tonal characteristic or behavior of that device, e.g. pitch, volume, cutoff frequency, etc.


In modern usage, a synthesizer that allows for more than one pitch to be played simultaneously, but in which all tones share the same articulative structure.

Read more in Synthesizer Polyphony—What Does It Mean?

see also: POLYPHONIC


Any harmonic above the fundamental frequency. Unlike overtones, partials include harmonics that are not integer multiples of the fundamental.



In modular synthesis, an arrangement of modules that are interconnected together to create distinct sounds. The "patch" concept encompasses both module interconnections and the individual settings of each module—all the necessary details that comprise the sound's current behavior.

In some non-modular electronic instruments, the term "Patch" may also be used interchangeably with the term "Preset," "Program," or similar.

Read more in What is a Modular Synthesizer?

Patch Bay

A device with a series of input and output sockets used to provide a singular location for convenient inter-device signal routing. Patch Bays are typically found in recording studios, where they allow engineers to easily manage signal routing through their preamps, rack effects, console, recording system, etc.

Patch Cable

A cable that is used for interconnecting modules in a modular synthesizer, or for connecting inputs and outputs on a patch bay. Patch cables may come in a variety of formats, including 1/4", 3.5mm, and banana.

Patch Diagram

In modular synthesis, a signal flow diagram that details all of the connections and important module settings of a given patch—typically employed in order to aid users in recreating patches.

see also: PATCH


A single cycle of a periodic waveform; may also refer to the amount of time that it takes for a single cycle of a waveform to elapse.

Periodic Waveform

A waveform that repeats in exactly the same pattern over and over, i.e. sine, square, saw, triangle.

Phantom Power

A DC electrical power supplied to active circuit microphones via the microphone cable. In contemporary designs, +48V is the most common supply voltage.


A position within a cycle of a waveform, measured in degrees from 0–360.

Phase Distortion

An approach to synthesis originally introduced by Casio in 1984 with the CZ series of synthesizers. In application, the phase of a carrier waveform is modulated by an angular modulation source, which is also hard-synchronized to the period of the carrier. It is similar to phase modulation synthesis, albeit the synchronization between the carrier and modulator, as well as an angular waveform of the latter, produce a distinct sonic flavor.

Phase Modulation

An approach to synthesis originally introduced by John Chowning, and commonly referenced as digital frequency modulation synthesis or FM synthesis. In application, the phase of carrier waveform is modulated by a modulation waveform with both set within an audible range. It is similar to phase distortion synthesis, albeit the spectra is represented by a Bessel function unless feedback is introduced.

Phase-Locked Loop (PLL)

A sonically distinct audio effect based on a dynamic relationship between the phases of output and input signals. The CMOS integrated circuit CD4046 and its various descendants use this phase comparison process to implement crude pitch detection systems. Beginning with the Schumann PLL, this type of circuitry has been commonly implemented in guitar pedals and synthesizer modules, in order to create chaotic audio-controlled synthesizer-like effects.

Read more in Weird FX: Phase-Locked Loops


An audio effect originally inspired by electronic music composer's early experiments with tape, where a single sound source would play on two tape machines slightly out of sync with each other. It was later recreated using electronic circuits blending the dry signal with a copy passed through a series of variable all-pass filters.

Physical Modeling

A branch of sound synthesis that implements mathematical equations and computer algorithms based on the acoustic properties of real objects in order to produce sounds which are similar to those of real physical objects or acoustic instruments.

Piano Roll

A type of music sequencer native to many digital audio workstations that features a two-dimensional grid, where the Y-axis corresponds to musical notes as they are laid out on a piano, and X-axis represents the dimension of time. A common interface for entering, storing, and editing MIDI data in "clips" in a DAW.

Ping (Filter Technique)

A technique that involves sending a short pulse or trigger into the audio input of a filter in order to induce a resonant tone with a strong starting transient. Depending on various aspects of the filter design and its current resonance setting, this may result in anything from percussive thuds and plucks to glassy ringing tones similar to modal synthesis.

Pink Noise

A noise signal whose spectral intensity halves at each octave interval. In contrast to the other popular type of noise, white noise, pink noise sounds smoother, as it has less energy in the high-frequency region.


A relative perception-based classification of musical tones on a frequency-related scale. It is related to, but it is not the same as frequency. Unlike frequency, which is an objective parameter, pitch is a subjective, psychoacoustic quality of sound.

see also: FREQUENCY

Pitch Bend

A control source common to synthesizers, often in the form of a wheel or joystick, which allows the user to alter the pitch of sounding notes. Also may refer to special type of MIDI control message designed to produce smooth pitch changes in response to the movement of such a controller. Unlike other MIDI control messages which are 7-bit, pitch-bend messages have a 14-bit resolution—which aids in preventing a "stepping" effect during value changes.

Pitch Shifter

An audio effect which allows for real-time changing of pitch of the original signal.

Polar Pattern

A term which refers to the general pickup area in which a microphone is most effective, or a diagram which displays the efficacy of microphone at all angles relative to the microphone's diaphragm. Common polar patterns include cardioid, supercardioid, figure-of-eight, omnidirectional, and more.

Read more in Microphone Polar Patterns Explained


A synthesizer voice structure that allows users to play multiple notes or tones simultaneously, allowing for chords or other multi-sound textures. Typically, the term "polyphonic" also implies that each individual "voice" has its own articulative structure independent from all other simultaneously sounding voices.

Read more in Synthesizer Polyphony—What Does It Mean?


In synthesis, polyphony refers to the maximum number of distinct, articulated tones an instrument can simultaneously produce. Synthesizers can be monophonic (meaning that they have a single voice), or can have any greater number of voices—for instance, it is common for synthesizers to have four, eight, or sixteen distinct voices of polyphony (though any number of voices is hypothetically possible).

Read more in Synthesizer Polyphony—What Does It Mean?


A common shortening of "polyphonic synthesizer."

Read more in Synthesizer Polyphony—What Does It Mean?


An input or an output socket on an electronic device. Alternatively, in the MIDI protocol, "Port" may refer to a self-contained group of sixteen distinct MIDI channels.

Potentiometer (or Pot)

An electrical component that uses mechanical contacts and semi-conductive carbon to implement a variable resistance effect. Potentiometers are common on electronic instruments: they commonly appear as rotary knobs or faders.

Preamplifier (or Preamp)

An electronic device that boosts a weak electrical signal before it is sent out for further processing or directly to a speaker. Commonly used to boost signals from microphones, passive pickups, contact microphones, and other low-level sources. Preamps may be standalone devices, but are also commonly part of audio mixers, synthesizers, guitar effect pedals, and more.


Short for preprogrammed setting. Presets are used on electronic devices and musical instruments to store and recall desired configurations and patches. Oftentimes, electronic instruments may ship with factory presets already programmed; typically, it is possible to add user-defined presets or to override the factory presets so that you can recall your own personal preferred settings.

Proximity Effect

A noticeable boost in the lower frequency range when a sound source is located close to the capsule of a cardioid microphone.

Pulse Code Modulation (PCM)

A technique of representing analog audio signals digitally.

Pulse Wave

A periodic waveform that alternates between two voltages—a high voltage and a low voltage. A square wave is an example of a pulse wave; however, while 50% of a square wave's period is high or low, respectively, pulse waves may feature any proportional balance of high and low voltages across their period. Commonly used on synthesizers to create brash, bright, and nasal textures.

Read more in Sine, Square, Triangle, Saw: the Difference Between Waveforms and Why It Matters

see also: WAVEFORM

Pulse Width

In synthesis, this refers to the proportional balance of high and low voltages within a single period of a pulse wave, sometimes referred to as "Duty Cycle." 50% duty cycle implies that 50% of a pulse wave's period is high, and that 50% is low—70% duty cycle, on the other hand, would imply that 70% of the pulse wave's period is high, leaving 30% low.

see also: PULSE WAVE

Pulse Width Modulation (PWM)

In synthesis, this refers to the continuous alteration of a pulse wave's width. This can create significant timbral alterations similar to filtering, or to the sound of two detuned oscillators.

see also: PULSE WIDTH


Q Factor

In synthesis, Q stands for the quality factor in filters—it is a term which some manufacturers refer to as Emphasis, or more commonly as Resonance.

see also: RESONANCE

Quadraphonic (Quad)

A four-channel listening situation that involves speakers positioned in four corners of a space. Quadraphonic audio was a common format in the 1970s, with a large number of vinyl albums distributed in various quadraphonic formats; likewise, modular synthesizer systems in the 1970s (such as those designed by Don Buchla) often featured quadraphonic mixing/panning facilities.


A process of limiting a continuous stream or a signal to a discrete set of values.

Quantizer (Pitch)

A device or a program that receives a continuous signal or a stream of note values in its input, and limits it to a predefined scale. This is a common tool in modular synthesizers, in which you can send in any control voltage to produce quantized (usually 1V/Oct) pitch control voltages at the output, turning LFOs, random voltages, or other modulation signals into sources of melodic control.

Quantizer (Rhythm)

Typically a feature in a program or a standalone device that aligns recorded musical events to a predefined grid size or a set note value.


Rack Mount

Refers to a piece of equipment meant to be mounted in a standard 19" equipment rack.

Ramp (Audio)

An asymmetrical periodic waveform. There are two kinds of ramp waves: upward, and downward. The difference is in whether the sharp edge of the waveform is at the beginning or at the end of its cycle. This is a common waveform in synthesizer oscillators and LFOs, sometimes used interchangeably with "Sawtooth".

Read more in Sine, Square, Triangle, Saw: the Difference Between Waveforms and Why It Matters


Ramp (Video)

An asymmetrical periodic waveform in video synthesis characterized by a combination of a sudden jump and a gradient between the brightest and darkest values.

Random Access Memory (RAM)

In computers and digital devices, RAM is a type of computer memory that can be read and manipulated in any order. It allows for data to be stored and retrieved nearly simultaneously. As opposed to ROM (Read-Only Memory), RAM may be manipulated or overwritten at will.


A sequencing technique that causes certain notes to repeat multiple times at a faster rate than a set clock rate before advancing to the next step. Commonly used to create stuttering or glitch-like effects; imagine Trap hi-hat sounds or the intro to "Baba O'Riley."

Read-Only Memory (ROM)

Read Only Memory describes a device that stores information permanently, as opposed to Random Access Memory (RAM), which contains re-writable memory.


Describes a system which responds simultaneously or near-simultaneously to external stimuli or programmed conditions and a given state of parameters. Alternatively, a process that happens exactly at the same time as when it is witnessed. Used in the audio world to differentiate between processes that can be executed in real time and those that require non-real-time computation to be executed.


A studio technique where a pre-recorded audio signal is sent back out of the recording environment into an external amplifier and/or an effects chain before it is re-recorded.


A signal processing element that is used to convert bipolar signals into unipolar ones. A half-wave rectifier does this by simply removing negative voltage excursions, leaving the output signal at 0V while the incoming signal is below 0V and leaving positive-going signals unaffected. A full-wave rectifier inverts the negative portions of bipolar signals in order to create an all-positive output signal.

Release (Compression)

The amount of time it takes for the gain reduction level on a compressor to reach a neutral setting after the source sound has gone below the compression threshold. Can impact the perceived "smoothness" of the compression.

see also: COMPRESSOR

Release (Envelope Stage)

Often, the final stage of an envelope, which defines the time between the end of a previous stage and a return to zero volts. Often, the release stage begins when the initiating key is released or incoming gate voltage goes low.

see also: ENVELOPE

Release Velocity

A rarely encountered type of MIDI data that represents the speed at which a key is released. Uncommon until recent years, release velocity is now a typical part of the MPE specification, and is available on an increasing number of synthesizers and controllers.


An increase in amplitude emphasizing a narrow band of frequencies located around the cutoff frequency of a filter. In synthesizers, resonance is often employed in order to induce more liquid, snarling, and vowel-like tones from a filter. Sometimes referred to as Q, Emphasis, or Peak.

see also: FILTER


An additive synthesis technique where any sound can be analyzed and then recreated by manipulating the frequencies and amplitudes of a bank of oscillators over time. Unlike sampling, the directly recorded audio is not utilized beyond the analysis stage.


A software or a hardware device that simulates the acoustic response of a space to a sound based on set properties. Commonly available in guitar effect pedal, desktop effect, modular synthesizer, rackmount processor, and effect plugin formats.

Read more in What is Reverb?


A color model based on red, green, and blue light.


A pattern distinctively arranged over a period of time.

Ribbon Microphone

A type of dynamic microphone designed around a thin metal plate attached to a moving coil that sits within a strong magnetic field. Now commonly used for the "vintage"-like characteristics, and commonly used to record vocals, brass/winds, electric guitar cabinets, and more.

Read more in Microphone Types Explained

Ring Modulator

A type of sound processor based on manipulating an amplitude of a sound source (carrier) with another signal (modulator). It is similar to amplitude modulation (AM), albeit in ring modulation the modulator signal is bipolar, which results in an output that contains only positive and negative sidebands without the original signal.

Read more in Weird FX: Ring Modulators



A special type of signal and corresponding connection used in early Moog modular synthesizer systems for triggering envelopes based on the principle of shorting the connecting wire to ground. It is directly incompatible with V-trig signals (trigger, gate) and therefore an adapter has to be used to interface S-trig signals with the more common gates and triggers of other modular synthesizers.


A digital audio protocol used for passing audio signals between equipment positioned at short distances. The common connector types are coaxial, RCA, and optical.

Sample (Digital Audio)

The smallest atom of signal representation in digital audio, representing the instantaneous amplitude of a signal at a given point in time.

see also: SAMPLE RATE

Sample and Hold

A software or hardware device which captures the values of a continuous analog signal at its input, and holds them at the output for a duration specified by the rate of the incoming trigger/clock—a means of converting continuous signals into stepped signals, or to temporarily store voltages. A common tool in modular synthesizers, standalone synthesizers, and more.

Sample Rate

A measure in digital audio that defines how many times per second a system takes a snapshot of a continuous analog signal—and determining the maximum audio frequency the system is capable of accurately reproducing. Along with bit depth, determines the total resolution of a recording.


A software or hardware device that allows for recording, storing, and manipulating audio signals in various ways. Often, samplers also feature some means of playing the recorded sounds as well—keyboards and sequencers are common playing interfaces for samplers.

Saturation (Audio)

A term used to describe subtler forms of audio signal distortion, i.e. tape, and tube saturation. Typically the result of nonlinear behaviors that result from analog systems reaching their upper thresholds for volume or reproducible voltage level.

Saturation (Video)

A parameter that defines the richness or vividness of color in an image.

Sawtooth Wave (Saw Wave)

A sawtooth-shaped, asymmetrical periodic waveform characterized by a harmonic spectrum that contains both odd and even harmonics with an amplitude relationship 1/n (where n is the number of the harmonic). Commonly used in synthesizers in order to create bright, brassy timbres.

Read more in Sine, Square, Triangle, Saw: the Difference Between Waveforms and Why It Matters

see also: WAVEFORM


A property in some electronic sound devices such as filters, mixers, delay effects of generating a periodic signal in response to a lack of under-dampening of the system (high resonance, feedback). In other words, the effect of inducing feedback within a system in order to get it to produce an audible tone. Characteristic of many filters within synthesizers.


A synthesizer topology that by default has a normalled signal connection structure between its modules that can be then over-ridden using user-accessible patch points. Unlike modular synthesizers, semi-modular synthesizers do not necessarily require patch cables in order to function.

Check out our Semi-Modular Synthesizer Buying Guide!



A hardware or software controller device that is used to record, and organize musical events across single or multiple playable timelines. Sequencers are common as standalone devices, as modules for modular synthesizers, or as integrated parts of many self-contained electronic musical instruments.


A "chained" connection between two or more audio processors, in which the output of one device feeds the input of another. As opposed to Parallel connections, in which a single source is fed to multiple otherwise independent processors.

see also: PARALLEL

Shelving Filter

A sound processor that can boost or attenuate bands of high or low frequencies, usually with a very steep cutoff curve. Commonly found in equalizers and DJ mixers.

Shift Register

A multi-stage software or hardware circuit which sequentially passes bits of digital data from one stage to the next upon a new clock cycle. Can be treated like a form of temporary data storage, and can be used for all sorts of tasks from peculiar rhythm generation to random pseudo-random number generation. Not altogether common as a patchable device, but an increasingly present part of the vocabulary of modular synthesists.


A sound effect characterized by a blend of dense reverb or delay and pitch shifting. Typically achieved by inserting a pitch shifter into the feedback loop of a delay or reverb, tuned to a consonant interval such as an octave or fifth.

Shotgun Microphone

A type of microphone commonly used in film production and field recording characterized by a very narrow directionality pattern, and usually an elongated shape. Typically features a lobar polar pattern.

Read more in Microphone Types Explained


A sound processing technique where an amplitude contour of one signal is used as a control source for shaping the dynamics of another signal. Commonly used for dynamic "ducking" effects.

Signal Processor

A software or hardware device used to manipulate or alter signals in some way.

Signal to Noise Ratio

A measurement that describes the proportional balance between the level of a signal to the level of self-noise in a particular system or recording.

Sine Wave

The simplest periodic waveform. It is generally considered a "pure tone", meaning that a sine wave contains no harmonics above its fundamental frequency.

Read more in Sine, Square, Triangle, Saw: the Difference Between Waveforms and Why It Matters

see also: WAVEFORM


Commonly refers to a portable, shallow enclosure for Eurorack modular synthesizers—derived from the name "boat," which is commonly used to refer to the chassis used to mount Buchla or Serge format modular synthesizers.

Slew Limiter

A software or a hardware circuit that limits a signal's possible rate of change—acting like a sort of lowpass filter. Generally used in order to smooth jittery signals, or, in a modular synth, to convert signals with sudden changes in voltage level into smooth, sloped signals. Sometimes referred to as a Slope Generator, Lag Processor, or Integrator.

Slew Rate

The rate at which slew limiting is applied to a signal.

see also: SLEW LIMITER

Soft Clipping

A type of audio distortion effect where the edges of a signal that exceed the maximum level threshold are gently rounded off, resulting in added harmonics. Unlike the hard-clipping effect, the added harmonics are added across the whole waveform at lower volumes, which leads to a milder and more pleasant sonic quality.

see also: CLIPPING

Soft Sync

A method of synchronizing the frequency between two oscillators, which can be achieved in several different ways. A common implementation involves a follower oscillator reversing direction at the beginning of every cycle of the main oscillator, or to nudge the follower oscillator to partly reset its phase according to user-specified settings, etc. Usually, soft sync does not have as pronounced an effect as hard sync, and is not as effective for the purposes of forced pitch tracking.

Read more in What is Oscillator Sync?

see also: HARD SYNC


An imaginary three-dimensional space created by a stereo speaker system. Generally referenced as an analogy in mixing, when attempting to sonically represent the way sounds relate to one another in natural space—therefore helping to strategize decisions about balance, EQ, panning, etc.


A feature on some synthesizers where the keyboard interface can be split into two or more sections, each controlling a different sound. A common feature of multi-timbral synthesizers, or MIDI controllers designed to control multi-timbral instrument setups.

Square wave

A waveform that contains harmonics that occur in whole odd-number multiples of the fundamental frequency. The harmonics, combined with the fundamental, give this wave a square shape. A square wave is a sub-type of pulse wave whose duty cycle is 50%.

Read more in Sine, Square, Triangle, Saw: the Difference Between Waveforms and Why It Matters

see also: WAVEFORM

Step Sequencer

A type of musical sequencer that breaks a measure up into a discrete number of individual steps, which can store and output user-defined information like pitch, velocity, note-on/trigger, and others either via MIDI messages or as analog voltages.

see also: SEQUENCER


A sound reproduction method that attempts to create a three-dimensional audio perspective with two independent sound channels—typically distributed to speakers on the left and right side of a listener, or into headphones.

Stutter (Effect)

A special type of delay-based audio effect created by freezing, repeating, and rearranging short segments of an audio signal. Typically associated with "glitch" aesthetics, given the similarity of the sound to malfunctioning audio playback technology.


A microphone polar pattern that exhibits similar directionality as omni microphones, although it is most receptive to sounds directly in front of it, and increasingly less at the sides, and at the back.

Read more in Microphone Polar Patterns Explained



A frequency emerging below the fundamental at an integer-related subdivision of the fundamental. Also known as an undertone, subharmonics are not, strictly speaking, a feature of naturally-occurring sounds—but they may be induced electronically through a number of processes.

Subtractive Synthesis

An approach to sound synthesis where a harmonically rich waveform (such as a saw or square wave) is taken as a source, and then the timbre is shaped by a filter—perhaps employing modulation sources like an envelope and/or a low-frequency oscillator (LFO).


Summing Mixer

An analog sound mixer, typically with a limited amount of controls, that is used to mix down multiple audio channels to a stereo track. Often employed in the final mixing process for tracks, even when the track was produced digitally in a DAW, in order to give the digitally recorded tracks a uniform sonic character before mastering.


A microphone polar pattern whose directionality is somewhere between a cardioid and a hypercardioid pattern.

Read more in Microphone Polar Patterns Explained



A special compound sound wave originally introduced by the Roland Corporation in JP-8000 (1996) synthesizer. A supersaw can be created by multiple slightly-detuned sawtooth waves stacked together—resulting in a buzzing, swarmy, unison-like tone from a single oscillator.


A compound sound wave, similar to supersaw, which is composed of several slightly detuned square waves stacked together. Less common than supersaw.

Sustain (Envelope Stage)

A stage in a modulation envelope which is held at a steady value for as long as the initiating key or pulse is active. In ADSR and similar envelopes, the sustain level is variable, allowing you to control the intensity of the envelope while keys are held. Typically, once a key is released, the sustain stage advances to a release stage.

see also: ENVELOPE

Sync (Synthesis)

A synchronization of the frequencies of two oscillators, usually executed by using one oscillator to reset the phase of another.

Read more in What is Oscillator Sync?


Sync (Video)

A reference video signal used to synchronize multiple pieces of equipment to the frame rate of a particular video source so that everything operates at the same speed—keeping images stable across multiple generators or processors.



An audio effect created by modifying the frequency spectrum of a sound by passing it through a performer's mouth, and imparting speech and vocalization patterns on it before it is routed via microphone to the output. The effect usually comes in stompbox format, with a tiny speaker in the middle and a plastic tube attached to it. The performer puts the other end of the tube in their mouth. As they play an instrument connected to the pedal, its sound passes through the speaker and the tube into the performer's mouth. By changing the shape of their mouth the sounds spectrum is altered, picked up by a microphone (sometimes also connected to the peda)l, and sent to its output. Famously used by Peter Frampton, and on 2Pac/Dr. Dre's "California Love."

Tape Delay

A type of delay effect where a magnetic tape is used for recording, modifying, and playing back sounds in real-time—allowing for the creation of echo-like effects. Though possible using two unmodified reel-to-reel tape machines, this technique was popularized by the 1960s Echoplex, and later by Roland in their line of Space Echo products.


A parameter that determines the pace of a given piece of music. In electronic music, it is commonly measured in the number of Beats Per Minute (BPM). The higher the BPM, the faster the tempo—and the more energetic the music is likely to seem.


One of the earliest electronic musical instruments, created by Leon Theremin in the 1920s. It is based on the principle that a performer controls the pitch and volume of an oscillator by moving their hands in space around two antennas.


A setting on a compressor that indicates an amplitude level at which compression starts to take an effect.

see also: COMPRESSOR

Through-Zero Frequency Modulation (TZFM)

A type of frequency modulation that occurs when the negative side of a bipolar modulation signal causes the carrier waveform to play backward, permitting "negative frequencies." This, in effect, creates a more pleasing sound than what is achieved by traditional FM, better maintaining a stable sense of pitch even with very high modulation intensities. Popular among modular synthesizer enthusiasts.


A perceived special quality of any sound that distinguishes it from all other sounds. It is characterized by a number of different attributes, of which the distribution and amplitude balance of overtones are particularly important. Timbre is also referred to as tone color or tone quality.

Time Lag Accumulation (TLA)

A delay/feedback technique invented in 1963 by one of Terry Riley's engineers, where a tape would be installed between two reel-to-reel machines. One machine is used for recording, the other one for playback while feeding back its output into the first one. The distance between the machines corresponds to the delay time. Later, the system was further developed by Pauline Oliveros for live-looping.

In effect, TLA is similar to modern looping systems—but it places value on the unpredictability of the looping point of particularly long delay lines rather than necessarily creating tempo-synced looping or delay effects.


A two-conductor phone jack format developed by Switchcraft. Although Tini-Jax connectors have a diameter of roughly 3.5mm, they differ from the common jacks of that size, and can not be used interchangeably—as Tini-Jax are actually a bit wider in diameter than common 3.5mm jacks. Tini-Jax are famously used in Buchla modular systems, as well as the original ARP 2600.

A standardized optical fiber connector system used for carrying high-resolution digital audio streams. It was originally designed by Toshiba in 1983. Commonly used for carrying ADAT optical signals.

see also: ADAT

Total Harmonic Distortion (THD)

A measurement of distortion present in an audio signal. It is determined by comparing the difference between input and output signals, and the value is expressed in percentages.

Track and Hold

A module that, like a sample-and-hold, has two inputs—one for gate, and one for reference signal—and one output. Unlike sample-and-hold, the module passes the reference signal to the output while the gate is high, once the gate goes low, the last value at the output is frozen until the gate goes high again.


Transistor Ladder Filter

An iconic low-pass filter design with a very distinctive sound. It was first developed by Robert Moog, and it was the only element of the Moog synthesizer that was patented. Famous for its warm, round, bassy response.


To move a note or a sequence of notes up or down in pitch by a specified number of steps or an interval value. A common feature of sequencers, keyboards, and modular synthesizer controllers.


High pitched tones or audio frequencies roughly in the range between 2–16kHz.


An audio effect characterized by a slow modulation of a signal's amplitude. Commonly available in guitar amplifiers, effect pedals, and software processors, tremolo can be used to impart slow dynamic swells, rhythmic "chopping" effects, and much more.

Triangle wave

A waveform that contains the same odd harmonics as a square wave, but they taper off as they get further away from the fundamental, resulting in a triangular shape. The sound is mellower than that of a square wave, with a notably "hollow" or "round" sonic character.

Read more in Sine, Square, Triangle, Saw: the Difference Between Waveforms and Why It Matters

see also: WAVEFORM


In modular synthesis, a trigger is a special form of Gate signal. Typically, a trigger is a short, fixed-duration electrical pulse, often used for starting and stopping events, activating envelopes, and clocking in a synthesizer patch. Like gates, triggers typically have a high "on" voltage and return to zero volts once they have completed; but unlike gate signals, triggers typically do not have variable duration, instead usually occurring in the course of 10 milliseconds or less.

see also: GATE (SYNTHESIS)


Short for "Tip-Ring-Sleeve", it is a 3-conductor phone connector, typically used for passing stereo or balanced audio signals. Typically, the Tip and Ring are used for signals, and Sleeve connects to the Ground. TRS cables commonly come in 1/4" and 3.5mm diameters.

True Bypass

A routing method in stompboxes that ensures that, when the effect is bypassed, the signal going through the pedal doesn't pass through any of its circuitry, and instead exits at the output without any alterations. This is useful for keeping signal chains as direct as possible, minimizing noise and inconsistencies that can accumulate with several devices in series.

True bypass is also useful for effects that precede particularly impedance-sensitive effects in your signal chain, such as fuzzes, or some types of wahs or distortions.




An audio signal carried through a two-conductor wire, where one wire transmits the signal, and the other is used as a reference voltage (ground). Common unbalanced signal connectors include 1/4" mono cables, 3.5mm mono cables, etc. The outputs of electric guitars, Eurorack synthesizer modules, and many other electronic instruments are unbalanced.


A signal that fluctuates only within positive voltage values, with no negative voltage excursions. Examples may include the signals produced by modulation envelope, envelope followers, and many other voltage sources in modular synthesizers.


In synthesizers, Unison indicates that two or more voices are utilized to play the same pitch simultaneously. Usually, "Unison" mode on a synthesizer is accompanied by a "Unison Detune" control, which can be used to offset the pitch of each voice relative to one another for buzzing, chorusing effects.



Short for "Voltage-trigger," V-trig it is the most common format for trigger/gate signals in synthesizers. Once activated by a keyboard or other controller, the V-Trig raises from its resting position of 0V to a maximum voltage (often 5V or higher), and stays there until it is deactivated (key released).

Typical modular synthesizer Gate or Trigger signals are types of V-Trig events. However, early Moog modular systems used a combination of V-trig and S-trig signals in order to initiate events, with S-trig typically produced by performance controllers and V-trig typically produced by sequencers or other modulation sources.



A special MIDI message that is determined by the strength with which a key is struck—usually translated into some change of dynamic or timbre. Note-on velocity is most common, however, modern synthesizers also occasionally include release velocity detection for understanding the rate at which a key is released.


Describes a MIDI control surface (typically with keys, buttons, or pads) that can repond to the velocity with which a performer strikes the control surface.


Modulation of a sound's pitch parameter. In synthesizers, an LFO is often used for vibrato effects, with LFO depth (the amount of the effect) controlled by a modulation wheel.

Virtual Analog (VA)

A synthesis method that aims at modeling the behavior of analog synthesizer components, and their tonal characteristics via digital signal processing techniques—allowing digital instruments to reproduce the feeling/behavior of analog synths at (typcially) a considerably lower cost. Originally developed by Clavia for use in the Nord Lead and Nord Modular synthesizers, Virtual Analog synthesis has become a common technique in synthesizer design.


A type of effect that transfers the harmonic structure of one sound onto another sound. An incoming signal (aka modulator or program signal) is split into a series of frequency bands via a bank of fixed-frequency bandpass filters. The individual outputs of each bandpass filter are then processed through envelope followers, which extract amplitude levels at each band. The modulation signals from envelope followers are then mapped to control another set of filters processing a complex waveform from a carrier signal (often an oscillator or an oscillator mixed with noise, though any sound could be used as a carrier).

Vocoders may appear as standalone effect processors, effect pedals, modules for modular synthesizers, or as part of a self-contained, standalone synthesizer.

Read more in Weird FX: Fixed Filter Banks


In a synthesizer, a "voice" is a complete soundmaking entity capable of producing a distinct, articulated tone. Usually, it is comprised of an oscillator, a VCA, an amplitude envelope, and sometimes a filter and filter envelope—though any sound source with the ability to be distinctly articulated could be considered a "voice."

Monophonic synthesizers (synthesizers that can only play one note at a time) have only a single voice—whereas polyphonic instruments have multiple voices that can be articulated separately from one another.

Read more in Synthesizer Polyphony—What Does It Mean?

see also: POLYPHONY

Volt per Octave (1V/Oct)

A standard in many synthesiers for voltage control over oscillators' pitch parameter, which corresponds to scaling of one full octave to one volt (or ~0.0833V per semitone). Useful for establishing compatible tuning specifications between multiple manufacturers, the 1V/Oct standard was developed in commercial instruments originally by Robert Moog—and this standard is by far most prevalent today, common for Eurorack modular synthesizers, desktop and semi-modular synths, CV-capable keyboards and sequencers, MIDI to CV converters, and more.


A difference in electric potential between two points. In modular synthesis, voltage level is a measure of the intensity of a signal—determining the strength of its influence on some aspect of the sound.

Voltage Controlled Amplifier (VCA)

In analog synthesizers, an amplifier whose level parameter can be controlled and modulated by a voltage input. In most synthesizers, a VCA is typically used in order to control a sound's loudness—in combination with control voltages from an envelope generator, a VCA can provide a sense of articulation.

see also: AMPLIFIER

Voltage Controlled Filter (VCF)

In analog synthesizers, a filter whose parameters can be controlled and modulated by a voltage input. In many synthesizers, a VCF's cutoff frequency may be modulated by an envelope, LFO, random voltage source, or other signal source in order to create a sense of timbral articulation, or other changes in timbre over time.

see also: FILTER

Voltage Controlled Oscillator (VCO)

In analog synthesizers, an oscillator whose parameteres can be controlled and modulated by a voltage input. In most synthesizers, a VCO's pitch may be controlled by a keyboard, sequencer, LFO, envelope, random voltage source, or other modulation sources. While pitch/frequency is by far the most common modulateable parameter on a VCO, in some VCOs, additional parameters (pulse width, waveshape, etc.) may also be voltage-controlled.

see also: OSCILLATOR



A specific type of waveshaping created by inverting the peaks of a waveform into a series of folds once its amplitude level starts exceeding a set threshold. Wavefolders were implemented in early instruments by Don Buchla (starting with the 200 Series and 500 Series), as well as later 1970s Serge modular synthesizer systems. They remained uncommon until the 2010s, when they became an increasingly common part of both Eurorack modular synthesizers and standalone instruments.


A graphical respresentation of a sound wave, where X-axis signifies time, and the Y-axis represents amplitude. Commonly used to describe the shape/timbre of synthesizer oscillators, or to visually display the contents of a recorded sound in a sampler or DAW.

Read more in Sine, Square, Triangle, Saw: the Difference Between Waveforms and Why It Matters


A device or a circuit that transforms one type of waveform into another. It is often associated with distortion synthesis via transfer function—an alteration in sound created by mapping an input signal to the output according to a mathematical function curve. Waveshaping is a general technique that can be implemented in countless ways; early instruments with sophisticated waveshapers included all instruments created by Don Buchla, as well as modular systems created by Serge Tcherepnin.


A three-dimensional table containing descriptions of several two-dimensional (time & amplitude) waveshapes. It is used as a primary sound source in wavetable synthesis, in which the user can typically modulate wavetable "position"—that is, the current waveshape selection within the table of waveshapes. Often used to produce sense of continuous evolution of timbre, or in order to create jarring juxtapositions of sonically distinct timbres. First commercially implemented in devices like the PPG Wave.

West Coast Synthesis

A term often used to describe sound synthesis methods developed by Donald Buchla, in contrast to conceptual approaches developed by Bob Moog (often referred to as East Coast synthesis). Commonly, this term is used to describe synthesis methods that involve generation of complex spectra through waveshaping and audio rate modulation, as well as methods of interaction based on indeterminacy and stochastically-defined behaviors.

The term "West Coast" was first applied to Buchla's designs in the 1960s, and gained popular use beginning in the late 2000s/early 2010s with the rising popularity of Eurorack modular synthesizers.

Read more in East Coast Synthesis vs. West Coast Synthesis and What is West Coast Synthesis...Really?


White Noise

A non-periodic waveform characterized by equal intensity across all frequencies. Commonly found in modular synthesizers, standalone synthesizers, and more.

Also the name of an awesome band/recording project with David Vorhaus, Delia Derbyshire, and Brian Hodgson.

Word Clock

A clock signal that is used to synchronize multiple pieces of audio equipment, usually carried over BNC connectors. Common on high-end digital audio equipment, ensuring that all devices are synchronized with one another for optimal performance.


X/Y (Stereo Microphone Technique)

A recording technique for capturing sound in stereo. It is accomplished by positioning two cardioid microphones as close as possible to one another in such a way that their overlapping capsules form a 90º angle—capturing a realistic stereo image.


A three-pin connector/cable type that is frequently used to carry audio signals for microphones and balanced instruments or professional audio devices.



A color scheme used in analog video electronics where Y carries luminance (brightness) and synchronization signals, Pb carries the difference between blue color and luminance, and Pr carries the difference between red color and luminance.