Harman EPM12, User Manual

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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)/DI Box The practice of connecting an electric musical instrument directly to the input of the 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 instance 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.
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 measurement 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, negative 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.