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A- Z of Synthesizer Related Terms, Elements and Modules.


ADSR - Attack, Decay, Sustain and Release.


AFTER-TOUCH - A keyboard with after-touch will respond to further pressure on the keys after they've been played. Effects such as vibrato and pitch-bending can be introduced just by pressing harder on the keys.


ALGORITHM - The term coined by Yamaha to describe the configuration (arrangement) of operators (digital sine waves) which creates each sound in an FM synthesizer.


ANALOG - Analog and digital are the two types of polyphonic synthesizer. Analog sounds are produced by altering the control voltages of a synthesizer's three main circuits - the VCO, VCF and VCA. These circuits correspond to the three main elements of sound: pitch, timbre and volume respectively. Analog synths are good at producing full, warm sounds.


ARPEGGIATOR - A device which produces an arpeggio based on one chord held down on the keyboard.


ATTACK - The first stage in the ADSR sound envelope, which describes how a sound varies with time. Attack is the start of the sound.


AUTO-BASS - A computerized feature of many home keyboards which generates an automatic bass accompaniment from chords or single notes played with either hand, and whose speed is set by a speed or tempo control.


AUTO CHORDS - Another home keyboard computerized feature which creates complex chords automatically when you hold down just one or two keys.


AUTO RHYTHM - A further feature of most home keyboards, auto rhythm brings into play a built-in drum machine which usually offers a selection of preset rhythms (various rock, disco and latin styles generally dominate) plus the facility for intros (before you start the tune) and fills (fancy little link pieces between different sections of the tune). The speed or tempo of the rhythm is determined by a speed control. When this feature is used simultaneously with auto bass and auto chords the whole lot is referred to as auto accompaniment, because it allows you to play your melody line over the top of a complete band.


CARTRIDGE - A solid state digital recording device somewhat smaller than a conventional cassette which slots into some keyboards and associated equipment to provide extra memory capacity for storing more sounds. There are two types - RAM cartridges and ROM cartridges. See also separate entries for RAM and ROM.


CHORUS - Not just the catchy bit in a song, but also an effects device which makes a sound fatter detuning it slightly and sending out both sounds at once. So in effect, it doubles up the sound. Chorus is also known as ensemble.


CV/GATE - This is the pre-MIDI method of controlling one piece of equipment from another. CV - control voltage - is the means by which the pitch of the note is conveyed, and the standard adopted by most manufacturers was one volt per octave. Gate simply means an on/off switch, so gate information tells the receiving instrument that a key has been held down (on) or released (off). Synthesizers with a CV/Gate input have a standard 1/4 inch jack socket labelled CV/Gate on the rear panel, and can be controlled by another synthesizer or by an analog sequencer with a CV/Gate output socket.


DCA - Digitally controlled amplifier - the digital equivalent of the analog synthesizer's VCA (Voltage Controlled Amplifier) which controls the volume of the sound.


DCO - Digitally controlled oscillator - the digital equivalent of the analog synthesizer's VCO (Voltage Controlled Oscillator). It is the basic sound source of the synthesizer, and digital control makes it more reliable, solving problems of tuning drift (going out of tune) which were common to earlier analog synths.


DCW - Digitally controlled wave - the digital equivalent of the VCF (voltage controlled filter) on Casio CZ sythesizers. It performs soundshaping and filtering duties.


DECAY - The second stage in the standard ADSR soundshaping envelope which describes the way a sound behaves with time. Decay describes the behaviour of the sound immediately after the initial striking of the key.


DELAY/DIGITAL DELAY - Delay is an echo effect which can be programmed to give you anything from a subtle repeat to thicken up a sound, to a cavernous echo-echo-echo. Digital delay offers far better sound quality, as each echo is identical to the original sound and doesn't fade away unless you set it to.


DETUNING - In synthesizers with two oscillators per note, it is often possible to tune one oscillator sharp or flat in respect to the other. This may be a slight detuning , to produce a fattening of the sound and effects such as phasing, or it may be in full note intervals (such as third, fourth or fifth) to produce a harmony effect from holding down a single key - a kind of two note chord.


DIGITAL - Digital technology has now largely replaced the older analog style of producing and controlling sound in synthesizers. It is much more sophisticated and reliable, though it was prone to eing too clean and clinical (lacking the 'warmth' of analog sounds) in some of its early incarnations. Digital technology is at the heart of computer design, and it is the application of computer technology to music which has brought about recent advances such as sampling and MIDI Digital synths may feature DCO's, or other digital sound sources such as the algorithms of FM synths, or sampled and resynthesized natual sounds, which are then shaped and modulated by filtering sections, envelope generators, LFO's, etc.


DIGITAL ACCESS CONTROL - Most modern synthesizers, whether digital or analog feature digital access control. The basis of DAC is the small LCD panel on which the sounds in the synth's memory can be displayed, one at a time, and edited, by calling up each parameter or element of the sound one at a time and increasing or decreasing its value as desired. It is a more laborious, less instantaneous form of control than the analogue control (knobs, switches and sliders) common to earlier analogue synths. But it is cheaper and takes up less space, since apart from the small screen, all that is needed is a set of buttons for the memory banks (these usually double as parameter buttons), and a knob or up/down buttons for changing the values.


DRUM PADS - Currently unique to a couple of Casio home keyboards are a set of pressure-sensitive hexagonal pads on the control panel connected to the instrument's built-in rhythm unit which can be 'played' with fingers or sticks as if playing actual drums.


EDIT - The most common way of creating the sounds you want to hear is by selecting a sound already programmed into the instrument's memory and editing it. Editing is achieved by taking any element or parameter of the sound to which the instrument gives you access and changing its value. With most polyphonic synthesizers and samplers, once you have edited the original sound until you hear exactly what you want, you must 'write'your edit into the memory, either in addition to or in place of the original sound, or the new sound will be lost when the synth is switched off. With many home keyboards and a few synths, however, there is no facility for programming the edit permanently and you can retain the edited sound only as long as the synth is switched on.


EFFECTS UNITS - Also known as signal processors, these are devices which apply some treatment to the sounds coming out of your instrument, such as reverb or echo. Professional signal processors are usually built to a 19-inch width and standard range of depths for bolting into a standard rack. Cheaper versions come in the form of floor 'pedals' designed primarily for guitarists. Some synths now have built-in digital delay lines to create a variety of effects, but most keyboards have some kind of effect built-in - chorus is very popular on synths and chorus or tremolo on pianos.


ENVELOPE GENERATOR/STAGES - The envelope generator is the element of the synthesizer's circuitry which controls the way the sound behaves with the progression of time. The most common type of envelope generator is four-stage, consisting of the parameters Attack, Decay, Sustain and Release (see separate entries). Some recent digital synths have introduced more sophisticated six - or even eight-stage envelopes, which simply means that the duration of the sound is chopped up into even more segments over which you can exert control. Envelopes are commonly applied to the volume and tone (filtering) elements of the sound.


EQ (EQUALISATION) - EQ is the 'professional' term for tone control. In synthesizers (the Roland D-50 excepted), ther is no EQ section as such, since the filters perform all the tone control tasks. But in pianos it is common to have treble, bass and even middle controls. These may be passive (which means that all they do is cut higher frequencies out of the frequency band they affect), or active, which means they can both cut and boost the frequencies in the relevant bands.


EXPANDER - This is a keyboardless version of a synthesizer or sampler, sometimes absolutely identical internally, but sometimes with extra features. It connects to your existing synth (or master keyboard) via MIDI and is a much cheaper way of giving yourself a bigger and more versatile sound than buying a second synthesizer. Expanders are also referred to as modules, and are usually designed to fit in a standard 19-inch rack or simply sit on top of your existing synth. Because of MIDI, you are not restricted to using an expander of the same make as your keyboard.


FILTER - The basic tone control device in a synth or sampler, the filter works by filtering out certain harmonics from the sound generated by the sound source (the VCO, DCO etc), and allowing the rest to get through. The common VCF (voltage controlled filter) may 'low pass', which means harmonics below a specified cut-off point get through; 'high pass', which dispenses with low harmonics; or 'band pass', which allows only mid-range harmonics to be heard.


FLOPPY DISK - A medium for storing digital information originally developed for computers. Most samplers rely on floppy disks for storing samples, which then have to be 'loaded' into the machine before it can be used. Similarly, sounds or sequences can be 'dumped' or 'saved' to disk. A few synthesizers, such as the Yamaha

DX7IIFD, have built-in floppy disk drive.


FM - A type of digital sound creation invented in America by Professor John Chowning which revolutionized when it was used in the Yamaha DX7, and is based on frequency modulation, like FM radio. It is remarkable for the naturalness or 'humanity' of the sounds it can create; also for clarity, percussiveness and cutting edge.


GLISSANDO - A fast run of notes. When this feature is available on a keyboard, it means that the synthesizer can automatically play such a run in semitones between the first and second keys you press.


LAYERING - If a keyboard has a layering facility, you can mix two sounds together. Doing this however, will usually halve the polyphony of your keyboard, say from eight-note to four-note.


LCD - Liquid Crystal Display: information displayed on a small illuminated screen, of the type found on a digital watch. Look out for back-lit LCD screens, because they can be seen in the dark- a very necessary facility for any gigging keyboardist, but one which many manufacturers mysteriously overlooked until quite recently. Some synths have LED (Light Emitting Diode) screens, which use illuminated figures.


LOOPING - A facility offered by most samplers in order to artificially lengthen the time of the sampled note, by repeating it continuously. The reverse of this is known as truncating.


MEMORIES - The means by which sounds are stored in synthesizers and other keyboards. Some memories may be purely preset, others programmable, which is to say you can store sounds you've created yourself. Groups of memories are usually called banks, individual ones may be called channels.


MIDI - Musical Instrument Digital Interface: a universal standard system introduced in the early 1980's which enables instruments made by one manufacturer to transmit or receive data to or from another instrument made by the same or another manufacturer.


MINI-KEYED - With small keys.


MOD/MODULATION - This enables a player to bring in a programmable vibrato effect (which makes the sound waver), using a wheel, joystick or after-touch.


MODULE - A keyboardless MIDI instrument (see expander) which can be controlled by any MIDI keyboard. In a completely modular system, you would use a MIDI master keyboard to drive as many synth/piano/sampler modules as required.


MONOPHONIC - Capable of playing only one note at a time.


OPERATORS - A term used by Yamaha to describe the digital sine waves which make up the sounds in FM synthesizers by distorting each other. As in FM radio, operators may be either carrier waves or modulating waves, depending on their position in the overall configuration (see algorithm). Operators replace the DCO's or VCO's of non-FM synths.





OSCILLATOR - The basic sound source of most synthesizers is an electronic device which oscillates (vibrates) and whose oscillation rate or frequency can be varied to produce notes of different pitch.


PARAMETER - A particular element of a synthesizer sound that can be altered separately (using a knob, button, slider, etc)


PATCH - Strictly speaking, a patch is simply a connection between two electronic devices, and early synthesizers often featured patchboards or patchbays which enabled you to connect the different elements of the synth in various different combinations using jack leads. Today, however, patch is generally an all embracing term meaning a specific sound, plus any routings and control functions you may have assigned to it before programming it into one of your instrument's memories.


PCM - Pulse Code Modulation is a method of digitally encoding (recording) natural sounds and storing them in such a way that they can be edited like synthesized sounds. Initially use to create more realistic percussion sounds in drum machines. PCM is now occurring more frequently as a sound source in digital synths.


PD - Phase Distortion is a type of digital sound generation involving distortion of sine waves. It was developed by Casio for its professional CZ (Cosmo synthesis) range of synthesizers.


PERFORMANCE ORIENTATED - An indication that an instrument has been designed with live work in mind, which is to say with its performance controls (those which you use for expression as you're playing the keyboard - mod wheel, pitch wheel, etc) conveniently sized and placed, and its programming and memory-recall facilities optimised for quick edits and changes.


PITCH - The frequency of a note. Treble is high-pitched, bass is low-pitched.


PITCH-BEND - Controlled by either a wheel, a joystick or after-touch on the keys, pitch-bend enables you to 'bend' a note to give the same effect as a guitarist bending his/her strings. The 'bend-range' can usually be programmed from about one semitone to a whole octave.


POLYPHONIC - Capable of playing more than one note at once. If a polyphonic synth is described as eight-note polyphonic, it can play eight notes at once, and so on.


POLYSYNTH - Polyphonic synthesizer.







PORTAMENTO - Technical term for glide, when the note you play swoops smoothly up or down to the next note. Available on many synthesizers.


PRESET - A preset sound, which comes built-in to your keyboard's memory. Some presets are editable, others you can only use as they are supplied.


PRO - Professional.


RACK-MOUNT - A rack-mount unit or module is one built to a width of 19-inches for bolting into a standard equipment rack. Keyboardless synthesizers, modules, expanders and some samplers are built to this design, as well as most studio-type effects units.


RAM - If your sounds are stored in RAM - Random Access Memory - you can recall them, edit them and store them in a permanently edited form at will. The programmable memory section of a synthesizer is RAM, and a RAM cartridge is an extra memory cartridge which plugs into the instrument and allows the same facility, like a blank tape that you can record over as many times as you want.


REAL-TIME - A recording made in 'real time' is recorded 'live', as if you were using an old-fashioned tape recorder (as opposed to the 'unreal' time of step time recording). Real time recording mistakes can usually be tidied up afterwards.


RELEASE - The fourth stage in the common ADSR envelope or behaviour pattern of a sound. It describes what happens to the sound after the key has been released.


ROM - If your sounds are stored in ROM - Read Only Memory - then they remain unchanged in that memory, whatever treatments you might apply to them while the instrument is switched on. ROM sounds are factory preset which are sometimes supplied in the synth memory but may come in extra ROM cartridges which plug into the instrument. With many synths, it is possible to unload sounds from internal ROM or ROM cartidge into the synthesizer's RAM, where they can be edited in the usual way.


SAMPLING FREQUENCY - Digital samplers record their samples by high speed 'sweeping' across the frequencies picked up by the microphone. They analyse the sound by breaking it down into thousands of portions every second, like thousands of points on a graph. The higher the sampling frequency or sample rate, the closer together are the points on the graph, and so the more accurately the sound is recorded. The 'mode' indicates the complexity of information which the sampling computer can process, 8-bit is considered low by today's standards, 12-bit is good and 16-bit is state-of-the-art. The maximum sampling time, measured in seconds, is simply the maximum length of the sample which the machine can record. With most samplers, the sampling frequency range goes down as the sampling time goes up. So the highest quality samples will be the shortest, and a long sample will be lower in quality. 40-50Khz is considered to be a professional sampling range, and at this sample rate you'd be looking for a sampling time of ten seconds or more.


SEQUENCER - A sequencer is a recording device, but it records note information rather than actual sounds, in the same way as a piece of sheet music does. When built into a synthesizer, or plugged into a synth or drum machine, the machine 'plays' the instrument according to whatever has been programmed into it. Programming may be in real time, when the device records note information exactly as it was performed on the keyboard, or step time, where notes and rests are 'tapped' in just as you would write them in on a music manuscript. Early sequencers were analogue devices, but modern ones are all digital, and may be called micro-composers or digital recorders.


SIGNAL PROCESSOR - See effects unit.


SLING-ON - A term applied to keyboards (especially remote keyboards), which are lightweight, often battery-powered, and fitted with guitar-type strap buttons to enable them to be slung on the shoulder and played like a guitar.


SPEC - Abbreviation for specification, which means a list of technical features.


SINE WAVE - The mathematical description of the simplest basic waveform or oscillation, which when represented graphically is like a repeating S-shape.


SPLIT - A split facility enables you to split the keyboard either at a set point or a point designated by you. You can then play one sound on one side of the split and a different sound on the other - for instance, a bass sound below and a string sound above.


STEP TIME - Enables you to program a sequencer or recorder one note or chord at a time - step by step - and to specify how long that note/chord should be, and where there are rests. This can then be played back at the correct speed. A step is one stage in the sequence, whether a note, chord or rest.


SUSTAIN - Third stage in the four-stage ADSR envelope which describes the way a synthesized sound behaves with time. It relates to the way the sound behaves while the key remains pressed down.


TIMBRE - The tone of a sound.


TOUCH-SENSITIVE - If a keyboard is touch-sensitive it responds to how hard you play it, either giving more volume, (in which case it's velocity-sensitve) or an effect (via after-touch). Velocity-sensitvity normally affects volume but can often be use to affect timbre or to bring in a second sound.


TRANSPOSER - A device within an instrument which allows you to change the pitch of the keyboard. A transposer is usually used to transpose a piece of music which is set in a difficult key so that it can be played in an easier one but will sound the same. So you can play in C major but the sounds can come out in F# major if you want.


TREMOLO - A device built into some pianos to produce a modulation effect. The modulation is of volume rather than pitch, although the term is commonly mis-used by guitarists to describe vibrato.


TRIGGERING - Activation of a sound source, as from the keyboard of the synthesizer. One device, for example a sequencer, may trigger (play) another, such as a synthesizer; or a master keyboard may remotely trigger a sound module via MIDI. Before MIDI, such triggering was achieved via trigger inputs/outputs (see also CV/Gate).


VCA - Voltage Controlled Amplifier - the circuit in a synthesizer which controls the volume of the sound (sometimes replaced in digital synths by a DCA).


VCF - Voltage Controlled Filter - the circuit in a synthesizer which controls the timbre or tone of the sound.


VCO - Voltage Controlled Oscillator - the basic sound source of all analogue synthesizers, whose pitch changes according to the size of the control voltage from the keyboard. Replaced in later analogue synths and most digital synths by the DCO.


VELOCITY-SENSITIVE - If a keyboard is velocity-sensitive, it responds to how hard you play it. The harder you play, the louder the sound. Velocity sensitivity can affect tone of a sound, or bring in another sound.


VIBRATO - Modulation of the pitch of a note above and below the true pitch to produce a pleasant wavering effect, normally achieved on keyboards by applying an LFO - Low Frequency Oscillator - to the note.


VOICE - Note or sound created by individual oscillator or oscillator group. The total number of oscillators determines the total number of voices, and thus how many notes can be played simultaneously.