Additive Synthesis — all sounds can be analysed as a combination of sine waves of differing frequencies and amplitudes. Additive synthesis is the construction of a complex sound by the addition of its sine wave constituents.

ADSR — Attack, Decay, Sustain, Release: the variable elements of a standard envelope generator. As applied to a VCO when a note is pressed the sound rises to its maximum volume, falls to a sustained level, then dies away. Envelopes can also be used to control VCOs and VCFs.

After-Touch — See Touch sensitivity.

Algorithm — A given combination of operators on a Yamaha FM synth.

Amplitude — The volume or amount of a signal — loudness.

Analogue — (As opposed to digital). Few synths today are entirely analogue, but any one using VCOs is considered in essence analogue. It is basically where the electronic source of the sound is CONTINUOUSLY variable, as opposed to a digital system where everything is done in quantified steps.

Attack — (See ADSR) The time taken for a note to reach its initial peak.

Auto correct — The facility of a real-time sequencer to correct for you musical timing errors to the nearest fraction of a beat as predetermined by you. Thus even the sloppiest playing becomes tight.

Auto-play — A system of automatic musical help and accompaniment found mainly on home keyboards. See Auto-Play.

Band Pass Filter — A special kind of tone control that allows only a predetermined band of frequencies to pass.

Bandwidth — The range of frequencies that a system, whether an amplifier, a digital reverberator or a filter, is handling, eg 40Hz to 12kHz (Hz = Hertz)

Bit — Derived from 'binary digit', ie a 0 or a 1 in a binary number.

Bitimbric — The facility to use two different sounds on an instrument simultaneously.

Byte — A digital number (referred to as a word) consisting of 8 bits.

Cassette Dump — The facility to record the contents of an instrument's memories (both sounds and sequencer information) on to a standard cassette tape recorder for future retrieval.

Clock — A regular low frequency square wave used as a timing reference to drive digital systems. Each clock pulse generally results in the conveyance of the next digital bit of information. 'Clock rate' is therefore the speed at which information is conveyed or 'clocked out'.

CPU — Central Processor Unit: the brain box that supplies all the instructions to drive a digital system, whether a standard computer or a digitally controlled synth.

Control Voltage — The DC voltage derived from the depression of a key or the movement of a control that is applied to a voltage controlled device such as a VCA, VCF or VCO to determine its action. CV ins and outs on the rear panel of synths are generally intended for the control of pitch information.

CV — See 'Control Voltage'.

Daisy chain — A number of MIDI instruments linked in series via their MIDI OUT, MIDI IN and MIDI THRU ports. In larger system this can cause delays — see 'Star Network' for superior alternative.

DCB — Digital Communication Bus: an interface system used exclusively by Roland before the inception of MIDI. DCB-MIDI-DCB converters are available from Roland.

Disk Storage — Similar to 'tape dump' but using computer disks which are far faster and more convenient (not to mention more expensive) in operation. Floppy disks are the smaller, cheaper, more common type of disk used as opposed to hard disks which hold more information, but which are very expensive and delicate and thus limited to upmarket systems.

EBU — See SMPTE

Hertz (Hz) — The standard unit of frequency where 1Hz — 1 cycle per second. For instance the A above middle C is 440Hz.

IC — Integrated Circuit: an electronic component containing a miniaturized circuit or circuits. Often seen in the classic 'micro chip' form.

Interface — A device that allows two or more systems to interact constructively with each other. If the interaction is two-way it can be termed a bidirectional interface.

LED — Light Emitting Diode: effectively a small coloured light widely used on keyboards to indicate the on/off status of the various functions.

MIDI — Musical Instrument Digital Interface: you should really have got the hang of this one by now. A standardised interface built into electronic instruments to allow them to be interconnected to form a larger complex musical system.

Multi-sampling — The facility to assign different samples, whether of the same instrument at different pitches or completely different sounds, to different sections of a keyboard.

Multi-timbral — Coined by Sequential with the introduction of their Six-Trak, it refers to the facility to assign a different sound to each voice (oscillator or set of oscillators) of an synth. Using a multi-track sequencer (actually built-in to the Six-Trak et al) you can then effectively programme each voice as a separate instrument, thus allowing a multi-instrumental arrangement to be created from a single synth. This is a very valuable facility to have within a MIDI system although to control through MIDI would require the external sequencer or computer to work in the 'Omni-Off Mono' mode.

Parameter — As used in the musical instrument industry it generally refers to any variable value. For instance volume, or the cut-off frequency of a filter, or the attack time of a note, etc; basically any setting that can be adjusted. A fixed value, such as an internal clock frequency, could be referred to as a fixed parameter.

PCM — Pulse Code Modulation: a system of digital encoding used for storage of any data, including audio information such as voices on synths and drum machines.

Pressure sensitivity — See Touch sensitity.

QWERTY Keyboard — the first six letters to be found on a typewriter: used to refer to a typewriter style keyboard as opposed to that of a piano, etc.

RAM — Random Access Memory: digital memory that can be 'written' into (ie recorded into) and 'read' from (ie played back from. See 'ROM'.

Real time — Of an action; meaning 'not recorded', but rather performed live in the actual moment.

Sampling — The recording of audio information in digital form for use as a musical source. See introduction to 'Sampling Keyboards' section.

Sampling Rate — The number of times a sound is measured per second in the process of converting it into a digital form for sampling. The higher the sampling rate the greater the degree of accuracy.

SMPTE/EBU — Time code used for synchronising two tape machines whether they be related to audio, film or video. The code is based on hours, minutes, seconds and frames, where the frames are frames of a film or video picture. Synchronisation is achieved by recording time code on a spare track on all machines involved and then using a computer assisted system to compare them as they play/wind. On playback this time code can be converted into MIDI information and thus programme changes etc within a MIDI system can be automatically controlled from the tape.

Software — The instructions that make a computer system, including one within a keyboard instrument, run in a certain way.

Step-time — (As opposed to real-time) — storing music 'step by step', note by note, separately specifying for each note its various values such as pitch, volume, time value — as opposed to recording a performance as it's played inTeal time'.

Star network (As opposed to a daisy chain) — where a number of MIDI instruments are connected in parallel either from an instrument with a number of MIDI OUT ports or via a MIDI parallel box giving a number of identical OUTS for a single IN. This format precludes the time delays that can be incurred when working with a 'daisy chain' system where a number of instruments are linked in series via MIDI THRU — MIDI IN.

Touch Sensitivity — The ability of a keyboard to respond dynamically to a player's touch. Velocity sensitivity responds to how hard you hit the keys whilst 'after-touch' or pressure sensitivity responds to the weight applied to a key after its initial depression. These functions can be applied to any number of an instrument's parameters such as volume or tone (VCA or VCF).

Velocity sensitivity — See 'Touch Response'.