permissible level, and set the stop level so that it just barely cuts in when the 160S is driven into heavy
gain reduction. As a general rule, the compressors should be as close to the amplifiers as possible in the
signal chain. If the 160S is placed before the EQ, for example, a potentially damaging boost in EQ won't
be seen by the 160S and the speakers may be damaged. For maximum sound pressure levels, large
sound reinforcement systems frequently use a separate compressor on each output of the electronic
crossover(s). For a stereo sound-reinforcement system, stereo linked 160Ss should be used on each band
(low-low, mid-mid, etc.).
The 160S as a line amplifier
To use the 160S as a line amplifier, adjust the
Compression
control to fully counterclockwise (1:1 posi-
tion), the
Threshold
control to full clockwise position (+10) and the
Output Gain
control to whatever
setting is required for the application. Remember that, as with any amplifier, excessive gain may lead to
output clipping of high level signals. To add compression, adjust the
Compression
control and the
Threshold
control to the desired settings.
Frequency-weighted compression
It is possible to separate certain vocals and instruments from a mix by frequency-weighted compression.
With an equalizer inserted in the sidechain circuit (but not in the audio path), the equalization settings
do not shift the timbre or frequency response of the audio signal. They merely alter the threshold
response of the compressor on a
frequency-weighted
basis (see diagram below).
With this arrangement, raising certain frequencies on the equalizer causes them to be suppressed in the
audio signal. A relatively high threshold setting can allow normal sounds to be unaffected while solo
and very loud sounds are held back. (Of course, when compression does occur, the level of the entire
program is affected.) Depending on the threshold setting, lower level fundamentals or harmonics will
not cause compression, and the program is not subject to the phase shift normally caused by program
equalization.
During the recording of cymbals and tom-toms, a compressor with an equalizer in the sidechain path
can help prevent tape saturation. The equalizer can be adjusted for boost with a peak of about 5kHz,
causing the cymbal to be compressed on a very loud crash, stopping tape saturation at high frequen-
Sidechain Applications
23
Source
Device
(mixer)
EQ
IN
OUT
Audio
Outputs
160S
Audio
Inputs
Audio
Outputs
Sidechain
Return
Sidechain
Send
Frequency-weighted compression
notes
160S
Operating
