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5 - Effects
Core Effects Descriptions
50 Creative Professional
Basic Controls
The three main controls of a compressor are the Ratio control, the Threshold control and
the Gain control.
If the signal level falls below the Threshold, no processing will take place. Signals
exceeding the Threshold will have gain reduction applied as set by the ratio control. This
important control allows you to dial in the range of amplitudes you want to tame. For
example, if you’re trying to trim off just the loudest peaks, set the threshold so the gain
reduction meter only shows compression during these peaks. One of the biggest
mistakes in using a compressor is having the threshold set too low. This adds noise as
the compressor will always be reducing the volume.
The Ratio control determines how strongly the compressor will affect the signal. The
higher the ratio, the more reduction will be applied. If the ratio is high enough, (above
10:1) the signal will effectively be prevented from getting any louder. In this situation,
the compressor will be acting as a Limiter, placing an upper limit on the signal level. In
general, ratios from 2:1 to 6:1 are considered compression and higher ratios above 10:1
are considered limiting.
The Post Gain control amplifies the signal after it has been compressed to bring it back
up in volume. If you don’t increase the gain, the compressed signal will be much lower
in volume.
Two other important controls are Attack and Release. Attack controls how quickly the
gain is turned down after the signal exceeds the threshold. Release controls how fast the
gain is returned to its normal setting after the signal has fallen below the threshold
again. An attack setting of about 10 milliseconds will delay the onset of compression
long enough to preserve the attack transients in guitar, bass or drums while allowing the
sustain portion of the sound to be compressed. Longer release times are generally used
to reduce the so called “pumping” effect as the compressor turns on and off. Don’t
make the release time too long, however, or the compressor won’t have time to recover
for the next pluck or hit. In general, the attack and release controls are used to smooth
out the action of the compressor, but they can also be used to create special effects.
The Pre-Delay parameter lets the level detector “look into the future” up to 4 milli-
seconds in order to anticipate upcoming peaks in the signal. This is accomplished
of course, by inserting delay into the signal path. This lookahead technique
allows the use of slower attack times without missing signal peaks. This
parameter is especially effective on drums and percussion.
The Input Meter allows you to monitor the strength of your input signal. Always try to
boost the signal before the compressor if you can.
The Compression Meter shows the amount of gain reduction being applied. Since this
meter displays how much the gain is being turned down, the meter moves from right to
left, instead of left to right like a normal meter.
Parameter Description
Threshold Threshold sets the input signal level above which dynamic range
compression takes place. Everything above the threshold will be
brought down in volume. Range: -60dB to +12dB
Ratio Sets the ratio of input signal level to output signal level, or “how
much” compression will be applied. Range: 1:1 to ∞:1
Post Gain Amplifies the signal after it has been compressed to bring up the
volume. Range -60dB to +60dB