Glossary - SoundCraft EFX User Manual

GLOSSARY

Auxiliary send An output from the console comprising a mix of signals from channels derived
independently of the main stereo mix.
Balance The relative levels of the left and right channels of a stereo signal.
Balanced A method of audio connection which 'balances' the wanted signal between two
wires, these wires also have a screen which carries no signal. Any interference is
picked up equally by the two wires, which results in cancellation of the unwanted
signal. In this guide, the term can refer to various circuit architectures. Connection
details are given in relevant sections.
Clipping The onset of severe distortion in the signal path, usually caused by the peak signal
voltage being limited by the circuit's power supply voltage.
DAT Digital Audio Tape, a cassette-based digital recording format.
dB (decibel) A ratio of two voltages or signal levels, expressed by the equation dB=20Log10
(V1/V2). Adding the suffix 'u' denotes the ratio is relative to 0.775V RMS.
DI(direct injection) The practice of connecting an electric musical instrument directly to the input of the
/DI Box mixing console, rather than to an amplifier and loudspeaker which is covered by a
microphone feeding the console.
Equaliser A device that allows the boosting or cutting of selected bands of frequencies in the
signal path.
Fader A linear control providing level adjustment.
Feedback The `howling' sound caused by bringing a microphone too close to a loudspeaker
driven from its amplified signal.
Foldback A feed sent back to the artistes via loudspeakers or headphones to enable them to
monitor the sounds they are producing.
Frequency response The variation in gain of a device with frequency.
Gain The amount of amplication in level of the signal.
Headroom The available signal range above the nominal level before clipping occurs.
Impedance balancing A technique used on unbalanced outputs to minimise the effect of hum and
interference when connecting to external balanced inputs.
Insert A break point in the signal path to allow the connection of external devices, for in-
stance signal processors or other mixers at line level signals. Nominal levels can be
anywhere between 0dBu to +6dBu, usually coming from a low impedance source.
Pan (pot) Abbreviation of 'panorama': controls the levels sent to left and right outputs.
42
Soundcraft EFX/EPM User Guide Issue 1110
Peaking The point at which a signal rises to its maximum instantaneous level, before falling
back down again. It can also describe an equaliser response curve affecting only
a band of frequencies, (like on a graphic equaliser), "peaking" at the centre of that
band.
Peak LED A visual indication of the signal peaking just before the onset of clipping, which will
distort the signal.
PFL Pre-fade listen: a function that allows the operator to monitor the pre-fade signal in
a channel independently of the main mix.
Phase A term used to describe the relationship of two audio signals. In-phase signals
reinforce each other, out-of-phase signals result in cancellation. Phase is a meas-
urement of relative displacement between two waves of identical frequency.
Polarity A term used to describe the orientation of the positive and negative poles of an
audio connection. Normally connections are made with positive to positive, nega-
tive to
negative. If this is reversed, the result will be out-of-phase signals (see 'phase'
above).
Post-fade The point in the signal path after a fader and therefore affected by the fader
position.
Pre-fade The point in the signal path before a fader, and therefore unaffected by the fader
position.
Rolloff A fall in gain at the extremes of the frequency response.
Shelving An equaliser response affecting all frequencies above or below the break frequency
i.e. a highpass or lowpass derived response.
Spill Acoustic interference from other sources.
Transient A momentary rise in the signal level.
Unbalanced A method of audio connection which uses a single wire and the cable screen as the
signal return. This method does not provide the noise immunity of a balanced input
(see above).
+48V The phantom power supply, available at the channel mic inputs, for condenser
microphones and active DI boxes.
Soundcraft EFX/EPM User Guide Issue 1110
43