Glossary of Synthesizer Terms

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Additive Synthesis
A system for generating complex waveforms or sounds by combining basic waveforms or sampled sounds prior to further processing with filters and envelope shapers. Additive synthesis is typically used in wavetable synthesizers like the Wavestation.

Aftertouch
A type of pressure controlled MIDI data determined by how hard you press a key or group of keys on a keyboard after the initial attack, and while the key is being held down. Sometimes called Poly Pressure. It is typically used to add expression to a performance.

Analog
An analog is a reproduction of something in another form. For synthesizers, this refers to the electrical voltages generated. They are analogs of the pressure waves that will eventually come out at the speaker as sound. These electrical signals are generated by an oscillator. Other electrical components can shape (envelope) and color (filter) the signal. The signal is prone to distortions from to the design and/or limitations of the electrical components used, which we may perceive as a warm and more natural sound than a digitally generated equivalent. Any synthesizer, new or old, that uses voltage controlled oscillators (VCOs) can be considered analog.

Arpeggiator
A device that steps from note to note for whichever keys are pressed (or latched) in a preset or random pattern.

CV (Control Voltage)
Control Voltages are used by analog synthesizers to control the oscillators, filters, envelopes generators, LFOs and other components. Originating in modular systems where it was necessary to patch these components together, CV jacks can also be found among hard-wired synthesizers where they were used as an early form of external MIDI-like control for connecting them to other analog devices. CV input and/or output jacks may also be labeled OSC In, Keyboard In, VCO in, or Key Volt.

DCO - Digitally Controlled Oscillator
An analog oscillating circuit controlled and monitored by a digital microchip. This offers a very stable, accurate, self tuning analog sound in a synth and is less likely to overheat or drift out of tune.

Digital
In a digital synthesizer, sounds are stored as a binary code of 1’s and 0’s in some form of permanent or volatile memory, typically called a sample. This sampled string of binary digits is converted to an analog signal by a Digital to Audio Converter (DAC) inside the synth. A Digital synth has very clean, consistent and stable sounds, offers lots of memory, can be lightweight and can offer much more control and variability of the sounds it can generate.

DIN Sync
Also known as Sync24, DIN sync is a form of tempo and start/stop synchronization used by old Roland drum machines and synthesizers. Most notably, the TR-606, TR-808, TR-909, TB-303, and MC-202. A DIN Sync cable looks just like a MIDI cable, but there is a difference. MIDI cables are wired differently and will not work with these older machines. To get a DIN Sync cable these days, you can find them at any electronics store as a generic 5 pin DIN cable. No rewiring is necessary.

Duophonic
(Two-sounds) A synthesizer that can play two notes or sounds at the same time is said to be duophonic.

Effects
Any form of audio signal processing that provides reverbs, delays, chorus, and other audio and spatial effects to sweeten, liven and animate audio as well as to create the sound of a space or environment.

Envelope
A shape that changes as a function of time. The shape of a synthesizer’s envelope is often controlled by Attack, Decay, Sustain and Release parameters (ADSR). The Attack is the start or onset of the initial transient sound. Decay is the roll-off of the sound’s waveform just after the peak of the initial attack. Sustain is the consistent volume of the sound sustained over the duration of time while a key is held down. And Release is length of time for the sound to end after the key is released. Envelopes can be applied to various aspects of a synth sound, such as pitch, filter cutoff frequency, and overall amplitude.

Filter
The timbre, also known as the color or nature of your sound is shaped by the filter. It can accentuate or attenuate certain frequency ranges. A type of equalizing device for subtractively eliminating selected frequencies from the sound spectrum of a signal and perhaps, in the case of a resonant filter, increasing the level of other frequencies around the cutoff point. The cutoff controls where the filter begins affecting frequencies. Many filters have an Envelope as well which is used to adjust the attack, decay, sustain and release of the filter’s effect on the sound being processed.

FM Synthesis
Frequency Modulation. One of the early forms of digital synthesis. FM is a type of modulation in which the frequency of a continuous carrier wave is varied in accordance with the properties of a second (modulating) wave in order to generate complex waveforms. When the modulating wave is in the audio range (above 20Hz or so), FM is perceived as a change in tone color, and that used in FM synthesizers to create their unique sounds. FM synthesis is used in most famously in Yamaha’s DX-series.

Gate
In synthesizers, Gate is a clock pulse signal often used to externally control or trigger the note-on, note-off state of an analog synth, to drive the rate of an the LFO or envelope, to start/stop a sequencer or arpeggiator and more. CV and Gate work together to provide the MIDI-like ability to control synths. Gate input and/or output jacks may also be labeled Trig, V-Trig, or S-Trig.

Hz/V
Herz per Volt. A form of control voltage (CV) typically used in Yamaha and Korg analog synthesizers.

Keyboard
A set of keys or levers, arranged in order of ascending pitch, which enables a piano, organ or synthesizer to be played by hand.

LFO
Low Frequency Oscillator. This is a very slow moving oscillator devoted to applications below the audible frequency range for the purpose of adding movement and expression to a synthesizer’s sound. Modulate the oscillator to create vibrato. Modulate the filter to create filter sweeps. Modulate the amp to create tremolo. An LFO can have multiple waveform shapes including square, ramp, sine, triangle, random or more and it’s speed (rate) and onset (delay) are often controllable.

MIDI
Musical Instrument Digital Interface. A standard digital language that allows synthesizers to control and be controlled by other MIDI synthesizers, sequencers and computers.

Modular Synthesizer
A synthesis system comprised of self-contained modules. These modules are specialized electronic circuits useful to producing and shaping sound. Modules are manually linked together using patch cords. Modular systems allow for extreme flexibility and customizability of your system but requires extensive programming knowledge and patience.

Monophonic
(One-sound) A synthesizer that can only play one note or sound at a time is said to be monophonic. Some monophonic synthesizers use note priority, such as lowest note or highest note priority. For example, in the case of lowest note priority, when holding down one key, the next note will not be heard unless it is a lower note than the one being held.

Multitimbral
A synthesizing instrument that can play two or more timbres (also called sounds or patches) at the same time. A typical multitimbral tone generator can play, for example, the brass, piano, and violin parts all at once. This allows for ensembles of instruments to be played from within one synth. Most digital synths and many analog string/ensemble synths are multitimbral.

Oscillator
An electronic device which generates a periodic signal of a particular frequency, usually a sine wave, but sometimes a square wave or other waveform. In an analog synthesizer, oscillators typically produce regularly repeating fluctuations in voltage - that is, they oscillate. In digital synthesis, an oscillator more typically plays back a complex waveform by reading the numbers in a wavetable.

Paraphonic
A type of polyphonic synthesizer with multiple oscillators (one or more per voice), but only one filter, amp, and/or envelope generator board for all the oscillators. A true Polyphonic synth will have independent oscillator, filter, amp and envelope generator boards for each voice.

Polyphonic
(Many-sounds) A synthesizer that can play two or more notes or sounds at the same time is said to be polyphonic. This allows for chords to be played and much more.

Portamento
An adjustable performance effect that glides or bends the pitch from one note to the next.

RAM
Random-Access-Memory is a fast, volatile form of digital memory typically used by digital samplers for live recording and editing your own samples. All data stored in RAM is lost when the device is turned off, and so must be stored to a more permanent disk or hard drive.

Ring Modulator
An effect where two audio signals or waveforms are combined and their sum and difference frequencies are output, usually creating a ringing metallic texture.

ROM
Read-Only-Memory is a permanent form of microchip memory that is used to store sounds or samples in digital synthesizers and sound modules. Sound libraries for these devices can often be expanded by adding additional ROM cards to expansion ports built in to the device. Typically these devices are called ROMplers.

S-trig
Short Trigger. Negative (-) gate trigger used in Moog synthesizers.

Sample
A digitally recorded representation of a sound.

Sample Rate
The number of samples taken per second in a digital synthesizer or sampler. Typical sampling rates vary from 11kHz to 48kHz. Compact Discs store audio at a sample rate of 44.1kHz.

Sampler
An instrument that records and plays back samples, usually by allowing them to be distributed across a keyboard and played back at various pitches.

Sequencer
A hardware device, software application or module used to arrange/sequence timed events into musical patterns and songs. An analog sequencer uses control voltages and gate triggers to control vintage analog devices. A digital sequencer usually uses MIDI and has more advanced capabilities than an analog sequencer.

Subtractive Synthesis
The technique of arriving at a desired tone color by filtering waveforms rich in harmonics. Subtractive synthesis is the type generally used by analog synthesizers.

Trigger
This is the same as Gate.

V-trig
Voltage Trigger. Positive (+) gate trigger used in Roland, ARP, Oberheim and Sequential synthesizers.

V/Oct
1 volt per octave. A form of control voltage (CV) typically used in Roland, ARP, Oberheim, Sequential and Moog synthesizers

VCA - Voltage Controlled Amplifier
A device that responds to a change in voltage at its control input by altering the gain of a signal being passed through it.

VCF - Voltage Controlled Filter
A filter whose cutoff frequency can be changed by altering the amount of voltage being sent to its control input.

VCO - Voltage Controlled Oscillator
An oscillating circuit controlled by an alternating analog voltage. This creates the sound in the synthesizer using basic waveform shapes like sine, sawtooth, square, triangle and PWM. Tuning can be unstable, synths can overheat and are often very heavy.

Velocity
A type of MIDI data that transmits or responds to the initial key attack - how quickly a key is pressed and/or released - typically used to control the volume for a sound.

Vocoder
Voice Operated enCODER. A type of effect typically used with vocals for its unique sound. Vocoding splits audio signals into multiple frequency bands, analyzes them, and applies the frequency and envelope characteristics of one sound (the Modulator, usually a vocal) onto the other sound (the Carrier, usually a synth pad or drum loop), making your instruments appear to speak.

Waveform
A signal, either sampled (digitally recorded) or periodic, being generated by an oscillator. Also, the graphical display of a sound pressure wave over time.

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