SoundCraft Spirit Live 3-2 - Manual (Page 5)

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The terms PRE and POST are often used in the context of Inserts, Equalisers and
Auxiliary Sends, and describe whether that facility is placed before (Pre) or after (Post)
another particular section. This is explained further in the detailed description of facili-
ties.
A mixer is often judged, amongst other factors, by the amount of Headroom avail-
able. This is a measure of the reserve available to cope with sudden peaks in the input
signal, without distortion caused by Clipping, when the signal becomes so high that it
would exceed the power supply rail voltages and is as a result limited. This commonly
occurs where gain settings are incorrectly set or where sources are improperly matched
to the mixer input. If the source signal is too high, clipping and distortion results. If the
signal is too low it becomes masked by the background noise which is present to some
degree in all mixers, although minimal in SPIRIT products. The diagram below illustrates
this point.
If the signal level is too low it may be masked
by the noise.
Signal Noise
If the signal level is too high, clipping distortion
may occur.
Clipped
Signal
Noise
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