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tions. Vocalists and musicians don't get the sense of being held back, but high average levels can be
maintained without speaker damage due to excessive heat buildup.
In circumstances where the 162SL is expected to cause no change in gain unless an emergency arises
(wildly excessive levels), some operators set the compression ratio to ∞:1, the threshold to the highest
permissible level, and set the stop level so that it just barely cuts in when the 162SL 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 162SL is placed before the EQ, for example, a potentially damaging boost in EQ won't
be seen by the 162SL 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 162SLs should be used on each
band (low-low, mid-mid, etc.).
The 162SL as a line amplifier
To use the 162SL as a line amplifier, adjust the Compression control to fully counterclockwise (1:1 posi-
tion), the Threshold control to full clockwise position (+20) 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.
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
Sidechain Applications
21
Source
Device
(mixer)
EQ
IN
OUT
Audio
Outputs
162SL
Audio
Inputs
Audio
Outputs
Sidechain
Return
Sidechain
Send
Frequency-weighted compression