Model D : What Are The Symbols, Terms and Abbreviations?

This glossary provides an explanation of useful symbols, terms and abbreviations.

For a full overview of the Model D please take some time to familiarise yourself with the User Manual located here:

This glossary provides an explanation of useful symbols, terms and abbreviations.

32'/16'/8'/4'/2': Used to describe the range of an oscillator, this term originates from pipe organs. The length of the pipe is inversely proportional to the pitch it produces, for example, a 4' pipe is one octave higher than an 8' pipe.

ADC or A/D: Analog to Digital Converter, used to describe the process of signal conversion

AC: Alternating Current

ADSR: Attack, Decay, Sustain and Release, an envelope with four stages. Amplifier: A circuit which increases the level of a signal.

Amplitude Modulation (AM): Modulation of the amplitude (or level) of a sound by another signal source. AM is used to produce tremolo using a low frequency modulation source.

Analog: Something which is proportional or similar to something else. In the case of the synthesizer, audio electronic circuits are another form of air pressure waves. Analog signals contain distortions from the components, topology, circuits and designs which are often perceived as warmer and more natural than their digitally generated counterparts.

Arpeggiator: An "Arpeggio" is a number of notes played sequentially instead of simultaneously. Some external keyboards have an Arpeggiator that responds to a number of keys being held by playing a sequence of notes.

Attack Time: The first stage of an ADSR envelope, used to control the initial part of a sound. Specified as the duration of time for an envelope to reach the maximum level after it has been triggered on by a key press or gate signal. Attenuate: To reduce the level of a signal. Automation: The recording and playback of control signals.

Balanced Audio: A type of audio connection that uses the three wires in a cable as part of a phase-cancelling arrangement to boost the signal and reduce noise.

Band: A range of frequencies.

Bandwidth: The difference between the upper and lower frequencies of a filter.

Bass: Lower frequencies in a signal ranging from 60 Hz to 250 Hz (Approximately B1 to B3).

Beat Frequency: When two waveforms of different frequencies are mixed together, the resulting waveform will have points of constructive and destructive interference. The beat frequency is equal to the difference in frequencies and is heard as a "beating" or amplitude modulation.

Beats Per Minute (BPM): Used to describe the tempo of a composition by specifying the number of beats which should occur in every minute.

Cent: Unit of measurement for pitch tuning. There are one hundred cents in a semitone.

Chorus: An effect which uses multiple copies of a signal played together and slightly out of time, to create a shimmering effect. Sometimes referred to as “Ensemble”.

Clock: A digital waveform typically square which is used as a timing source for other components in a system.

Continuous Controller: A type of MIDI message assigned to a specific parameter. When the parameter is adjusted a continuous controller messages are sent. If the assigned continuous controller is received then the parameter will be adjusted.

Control Voltage (CV): A voltage signal used to control any parameter. Was common on synthesizers before MIDI, and is now found mostly on modular synthesizers.

Cross-Modulation (X-Mod): Two oscillators modulating each other at the same time. The outputs is a mix of the sum and difference of the oscillators. The term is also used to describe the ability for parameters of a synthesizer to be able to modulate other parameters.

Cut-Off Frequency: The frequency which a filter is set to. Beyond this frequency (in a low-pass filter, the most common), the sound is cut off (attenuated) at a rate set by the slope of the filter response curve.

Cycle: In a sound wave, the cycle refers to a single repetition of a wave-shape. For example, in a square waveform, it is the time from a positive edge to the next positive edge.

DAC or D/A: Digital to Analog Converter, used to describe the process of signal conversion

Data: Digitally stored information dB: Symbol for “decibel”. A unit of measurement of the loudness of sound. See dBu.

dBu: A unit of measurement of sound used in professional audio. Derived from the decibel, where the “u” stands for unloaded, this unit is an RMS measurement of voltage based on 0.775 VRMS, which is the voltage at which you get 1 mV of power in a 600 Ohm resistor. This used to be the standard impedance in most professional audio circuits.

DC Offset: An imbalance that sometimes occurs in A/D converters. It is a constant voltage that is present, which can eat up headroom and cause clicks and pops during editing.

Decay Time: The second stage of an ADSR envelope. Specified as the duration of time for an envelope to reach the sustain level after the maximum level has been reached during the attack stage.

Default: An initial value for parameter, i.e., the value before any changes have been made.

Delay: An effect by which a reproduction of a signal is played back later then its original. Primarily used for echo, but also is the basis for phasing, flanging, chorus and basic reverb type effects.

Detuning: The action of adjusting the pitch of an oscillator from a reference point or another oscillator. When oscillators are detuned slightly they will make the output sound "fatter" or "wider". When oscillators are detuned heavily to note intervals it can create harmonies.

Digital Audio Workstation (DAW): A computer based recording system. More commonly used to describe the software package used to record, process and mix.

Digitally Controlled Oscillator: An analog oscillator circuit controlled and monitored by a digital processor. The advantages over a VCO is increased stability which results in far less tuning drift.

Digital Signal Processing (DSP): The numerical manipulation of signals, usually with the intention to measure, filter, change, effect, produce or compress continuous analog signals.

Distortion: An effect based on pushing the boundaries of what a specific technology or implementation can achieve. At the point where technology begins to overload, overdrive, clip, saturate or generally misbehave is where distortion starts to appear. Examples include tape, valve, transistors, and also digital algorithms and processes.

Dynamic: The range of levels in an audio signal, from the softest to the loudest.

Dynamic Processor: A device used to control and/or change the dynamics of a signal.

Dynamic Range: The difference between the lowest level and the highest level an audio system can produce. 37 MODEL D User Manual

Effect: One of a number of audio processes that can be applied to a signal to modify it, such as reverb, flanging, phasing, delay etc.

Effects Send: A copy of the channel signal which is sent to an effects processor in order for it to be returned.

Effects Return: An effected audio signal which is returned to mix with the original channel signal.

Envelope Generator (EG): An envelope signal which can be adjusted to a specific shape in order to control the way a sound behaves over time.

Equalisation (EQ): Processor used to adjust the volumes of various frequency ranges for creative or corrective purposes.

Exponential: A mathematical function of growth or decay where the independent variable is the exponent. This results in a "hockey stick" shaped curve.

Expression Pedal: A Pedal which can be connected to an expression input and used to send a control signal dependant on the position of the pedal. The control signal can then be used to modulate other parameters, and/or to add expression.

Fader: A physical linear control also known as a slider, or slide potentiometer which can be used to adjust a parameter.

Feedback: A loop created between an audio input and an audio output of an audio circuit, system or processing block.

Filter: A device that attenuates certain frequencies while letting other frequencies through. Using a filter to reduce harmonics, changes the timbre or color of the sound.

Frequency Modulation (FM): Using one frequency to modulate another frequency's pitch. When the modulation source is in the audio range, it can be perceived as a change in the timbre or color of the sound. FM can be used to create a wide range of rich and complex sounds and is often described as having a clear and distinctive timbre.

Frequency: The number of times that a sound waves cycle repeats within one second.

Fundamental Frequency: The lowest frequency of a periodic waveform.

Gain: The amount of signal level increase provided by an amplifier stage.

Gate (Synthesizer): A signal used to trigger an event, such as a note or an envelope.

Gate (Dynamics): A device used to cut off the level of a signal when it falls below a specified threshold. Can be used to cut background noise, control reverb tails, or creatively to produce chopping type effects.

Glide: See Portamento.

Global: The settings and parameters which govern the general operation of the synthesizer and are not directly associated with the voice engines.

Harmonics: A series of integer-related sine waves at varying levels creating different timbres.
Waveforms (other than a pure sinusoidal) generate various harmonics which help define the character of the sound.

Hertz (Hz): A unit of frequency equal to one cycle of a wave per second.

High Pass Filter (HPF): A filter that attenuates lower frequencies from a signal, leaving the higher frequencies unaffected.

Hum: Undesirable low-frequency tone (typically 50 or 60 Hz) present in a signal due to grounding problems or proximity to a power source or power cables.

Impedance (Z): Opposition to the flow of alternating current in a circuit, measured in Ohms.

Insert: A point in a processing chain where a device can be inserted.

Keyboard: A range of keys, arranged in order of ascending pitch, which enables the synthesizer to be played by hand.

Keyboard Tracking: Allows the control signal from played keys to adjust another parameter. Commonly used to open a filter as higher notes are played which then enhances harmonics.

Kilohertz (kHz): A unit of frequency equal to one thousand cycles of a wave per second.

Latency: A delay introduced by processing. Measured by the time it takes to produce a signal after a request has been made. In a synthesizer, it is the time taken to produce a note after a key has been played. In an audio interface, it is used to measure the time it takes for an input signal to reach the processor, or for a signal from the processor to reach the output.

Level: Used to describe the magnitude of a sound, often relative to an arbitrary reference.

Limiter: A device used to limit the level to a range of values irrespective of the input level.

Linear: Used in audio to describe a straight line response of circuit or process which results in a change which is directly proportional to an independent variable.

Line Level: A nominal operating level used by audio equipment. Professional line level is normally +4 dBu and consumer line level is -10 dBv.

Looping: Automatically restarting a function at the end of a period of time or defined cycle, to create a continuous loop.

Low Frequency Oscillator (LFO): An oscillator that commonly runs at a very low speed and is used to modulate another parameter.

Low Pass Filter (LPF): A filter that attenuates higher frequencies from a signal, leaving the lower frequencies unaffected.

Mark to Space Ratio: The ratio between the positive and negative parts of a rectangular waveform, or pulsewave.

Meter: Visual device to indicate the level of a signal.

MIDI (Musical Instrument Digital Interface): A technical standard that describes a protocol, digital interface and connectors and allows a wide variety of electronic musical instruments, computers and other related hardware/software devices to connect and communicate.

MIDI Clock: A clock signal which is broadcast over MIDI to ensure that devices are synchronised. Also known as MIDI Beat Clock or MIDI Timing Clock.

MIDI Message: Data or information transmitted from one MIDI device to another. Each MIDI message contains at least two numbers: one that identifies the type of message being sent, and another which represents a value for the selected type of message.

Midrange: Frequencies in a signal ranging from 250 Hz to 5 kHz (Approximately B3 to D#8).

Mix: The balance of level between one signal and another.

Mixer: A device that blends input signals into composite signals for output.

Modular Synthesis: A synthesis system comprised of a number of modules which can be connected in many different ways. Modules can perform a single function such as an oscillator or filter or perform multiple functions.

Modulation: The process of controlling one or more properties (destinations) of a signal using another signal (source).

Modulation Wheel (Mod Wheel): A wheel located to the left of a keyboard that allows you to change specified parameters in real-time. 38 MODEL D User Manual

Monitors: Studio quality loudspeakers, providing an accurate representation of the audio signals.

Mono: A single signal.

Monophonic: Only one note can be played at any given time, as there is only a single voice.

Mute: Function that allows a signal to be silenced.

N/A: Abbreviation for "not applicable" or "not available".

Noise Generator: A circuit or process that produces a random (or aperiodic) signal. The frequency response can differ depending on the type of noise.

Note-Priority: Determines which note is played when more notes are held simultaneously than the number of available voices (often: low/high/last).

Octave or Oct: Unit of measurement for pitch. Every time the frequency of a waveform doubles, the pitch increases by one octave.

Ohm (Ω): Unit of electrical resistance.

Oscillator: An electronic device which generates a periodic signal used to form the basis of a synthesizer program.

One Shot: A single event that has to be triggered each it is required.

Output: The signal sent out by a device or process. Also used to describe the physical socket where a signal leaves a device.

Overtone: Any frequency that is present in a waveform that is higher than the fundamental frequency of that waveform.

Pad: A program that is usually characterized by slow attack and release times.

Panning / Pan: The positioning of a signal within a stereo image.

Parameter: A setting whose value can be changed.

Parametric EQ: A type of EQ that allows all of the parameters of equalisation to be changed, including centre frequency, boost/cut in gain and bandwidth.

Partial: Any of the sinusoidal waveforms which form part of a complex tone.

Patch: The cables used on modular synthesizers (or synthesizers with modular compatibility) to connect devices together. Patch cables can carry audio, gate or control voltage signals.

Period: The time that it takes a wave to complete a full cycle. Period is calculated by dividing 1 by the frequency

Phase: A measurement (in degrees) of the time difference between two waveforms, or between a single waveform and a reference point.

Phaser: An effect which uses a series of notched all-pass filters (also called stages) to create a comb-filter response which does not always have harmonic relationships between the notches. The result is a sweeping effect similar to a flanger but smoother and often more natural sounding.

Pink Noise: A type of signal that has equal power in each band. Human hearing is roughly logarithmic, therefore each octave is discerned to have an equal amount of power across the audible spectrum.

Pitch: A quality of sound that makes it possible to judge if a sound is higher or lower than another.

Pitch Bend / Pitch Bend Wheel: Controlling the pitch of a note after it has been played.

Pitch Shift: Alteration of pitch or frequency, but without adjusting tempo.

Pole: A section of a filter stage. The more poles a filter has, the steeper its attenuation slope will be, and the more accurate the filter will be.

Polyphonic: Capable of playing more than one note at once.

Polyphony: The number of notes a polyphonic synthesizer can play simultaneously.

Portamento: An adjustable performance effect that glides or bends the pitch from one note to the next. Post: The point for accessing audio just after it leaves a specific component or stage. For example Post-Fader audio is affected by the fader.

Pre: The point for accessing audio just before it reaches a specific component or stage. For example, Pre-Fader audio is not affected by the fader.

Preset: A program or part of a program that is built into synthesizer patches that are sometimes fixed and sometimes editable.

Program: A complete set of parameters and settings which the synthesizer uses to create a specific sound.

Power Supply Unit (PSU): The component in a system which is responsible for supplying and managing power.

Psychoacoustics: The study of the perception of sound, that is, how we listen, our psychological responses, and the physiological effects on the human nervous system.

Pulse Wave: Similar to a square wave, but without symmetry. Also known as a "Rectangle Wave."

Pulse Width Modulation (PWM): Modulation of the pulse width (the duty cycle of a pulse wave measured as a percentage). A pulse width of 50% has equal positive and negative sections and is considered a square wave.

Q Factor: A bandwidth (or selectivity), of a particular band in an equalizer. The higher the Q Factor, the wider the bandwidth.

Rate: The speed at which a particular device is operating.

Release Time: The fourth and final stage of an ADSR envelope. Specified as the duration of time for an envelope to reach zero after the played key is released.

Resonance: The emphasis/boost of frequencies around the cut-off point just before attenuation starts to occur. As resonance increases, it will reach a point where the filter will start to self oscillate, producing a signal even when there is no input.

Reverb: An effect where the ambience of a physical space is simulated.

s: Symbol for "second," a unit of time.

Sample Rate: The number of digital samples used every second to represent an analog waveform.

Sample Resolution (Bit Depth): The number of digital bits used to define the amplitude of an analog signal. Higher resolution results in greater dynamic range.

Sawtooth: A waveform that combines an instantaneous rise or fall, followed by a gradual linear incline or decline. The name comes from the waveform's similarity to the teeth of a saw.

Semitone: A chromatic half-step. There are twelve semitones in an octave.

Sequencer: A programmable device or module used to arrange/sequence timed events into musical patterns and songs.

Self-oscillation: Occurs when the resonance of a filter is increased to the point where it will begin to generate a sine wave independently of any input.

Signal flow: The path of a signal from one module (or component of a system) to another.

Sinusoidal / Sine Wave: Mathematical description of a smooth waveform that contains only the fundamental frequency and has no additional harmonics. The shape resembles the letter "S" rotated 90 degrees. 39 MODEL D User Manual

Slew Rate: The rate of change of a voltage or control signal.

Spectrum: First used to describe the full range of colors in visible light, the term is also used to describe the full range of frequencies in the audio spectrum.

Square Wave: A symmetrical waveform that combines an instantaneous rise or fall, followed by a positive or negative steady state. The name comes from the waveform's similarity to a square.

Step: A step is one stage in a sequence and can be a control signal, single note, chord or rest.

Stereo / Stereophonic: The most common method of sound reproduction where separate channels, left and right, are used to give the impression of direction.

Stereo-Field / Stereo Image: A virtual space created by stereo loudspeakers/monitors.

Sub-Bass: Frequencies in a signal ranging from 10 Hz to 60 Hz (lower than C0 to approximately B1).

Subtractive Synthesis: A technique of creating sounds by filtering waveforms which are rich in harmonics.

Sustain Level: The third stage of an ADSR envelope. Specified as "the level an envelope will return to, after the decay stage". The envelope will remain at the sustain level until the played key is held.

Sustain Pedal: A Pedal containing a switch which can be connected to a sustain input and used to send a control signal dependant on the state of the switch (On/ Off). The control signal can then be used to modulate other parameters, and/or to add expression.

Synchronisation (Sync): Coordination of timing between devices.

Sync (Tempo): A function where an cyclical event such as an LFO is synchronised to a tempo value.

Sync (Oscillator): A function where one oscillator is synchronised to another. The waveform of the slave oscillator is reset whenever the waveform of the master oscillator restarts.

Sync (Arp/Seq): A function where an arpeggiator or sequencer is synchronised to a tempo value.

Sync (Key): A function where an event is synchronised to the pressing of a key.

System Exclusive (SysEx) Messages: Multi-byte messages used to transfer a complete program or globals, in the form of request - response.

Threshold: Level at which dynamics processing will begin to operate.

Tempo: The speed at which a composition should be played, usually expressed in beats per minute (BPM).

Threshold: In dynamic effects, this is the level that must be passed before the processing is engaged.

Timbre: The tone, character, or aesthetic qualities of a sound.

Transposition / Transpose: A function that allows you to shift the entire keyboard up and down in pitch.

Treble: Frequencies in a signal ranging from 5 kHz to 20 kHz (approximately D#8 to above C10).

Tremolo: A periodic change in amplitude.

Triggering: Activation of a function, such as the start of a note, envelope, or LFO.

Tune / Tuning: The process of adjusting the root pitch of the instrument to a specific reference frequency.

Unbalanced Audio: A type of audio connection that uses two wires in a cable and does not offer the noise rejection qualities of a balanced system.

Share this page