10
Begin with the knob fully counterclockwise and the compressor switched ON, then slowly begin turning clockwise until
you begin to compress the signal. You will hear the signal compress, and you will begin to see the GR meter light up. The
lower the threshold setting , the more the incoming signal will be attenuated and the more lights will light up on the GR
meter.
SETTING THE ATTACK RATE
The rate at which you want the compressor to start the attenuation of the signal (
attack phase
) depends on the character,
or envelope, of the signal entering the compressor. If the signal has sharp or fast attack (percussive sounds, snare drum)
that you wish to attenuate, select a fast attack rate to sense the initial impulse of the signal and attenuate it in time. If you
want the compressor to react slower and not attenuate the initial impulse of the signal, select a longer attack time. Using
a slower attack time may be more appropriate with signals with a slower, more gradual envelope (strings, woodwinds).
SETTING THE RELEASE RATE
The rate at which you want the circuit to release its attenuation of the signal (
release phase
) is set with the release control.
This is the functional opposite of the attack control. If the signal has a shorter decay, it may be best to set a shorter release
time. A helpful approach to setting the attack and release time may be to consider the basic pulse of the signal you’re
compressing. To avoid the typical artifact known as ‘pumping’, where you can clearly hear the compressor working, it is
important to set the attack and release times to match the signal to where they are moving naturally with the dynamic
fluctuations of the signal.
SETTING THE RATIO
The compressor’s ratio control is used to set input/output ratio of signals above the threshold. For instance, a setting of
3:1 means that if the incoming signal is 3dB over the threshold level, that signal will leave the compressor around 1dB
over the threshold level. The highest setting of this control is 12:1, meaning that signals far over the threshold setting
are reduced by a much higher ratio – more compression. So lower ratio settings mean lighter compression amounts. We
recommend starting with lower ratios and working upward as necessary.
SIDECHAIN CONTROL
Normally, the compressor’s sidechain circuit uses the internal audio signal to trigger its response. But in sidechain
mode, the sidechain circuit uses an external signal input (from the LINK IN jack on the rearpanel) to determine how the
compressor responds. Examples of using an external sidechain signal include
ducking
and
de-essing
.
Ducking is an effect used to automatically reduce the level of one signal when another signal is present. Think of a DJ’s
microphone automatically reducing the level of the music when he or she is speaking. It involves routing a separate
signal from a microphone (or any other source) into the sidechain input of the m103. This signal is what the compressor
reacts to and thereby would typically reduce (or duck) the level of the main signal in the m103. You would use the
compressor controls to determine the amount, rate and duration that incoming signal ducks the main signal.
De-essing is used to decrease excessive sibilant (‘s’ or ‘sh’) sounds in a voice. This is accomplished by inserting a copy
of the signal into the sidechain input which has been equalized (by an external equalizer) to emphasize the frequency
where the sibilance lies (usually 6-9k). This inserted signal makes the compressor react to and thereby reduce only the
places in the signal where troublesome sibilance lies.
There are many other functional and creative ways to use sidechain input, more than can be illustrated here. Again, the
more you know, the more powerful it can be.
GR METER
This meter shows the amount of gain reduction being applied by the compressor. The LED’s illuminate right to left, with
one LED representing 1dB of gain reduction and ten LED’s representing 10dB’s of gain reduction or more. Selecting a
lower threshold setting will activate the compressor with relatively lower signal levels and will be reflected on the GR
meter as more gain reduction. Selecting a faster ATTACK time will show on the meter as the LED’s turning on faster,
selecting a slower RELEASE will show on the GR meter as the LED’s staying lit longer. There is no correct setting for this
meter – it is simply displaying how the compressor is working. If all the lights are on, you are probably SQUASHING IT! If
only the first three are lighting up, you are applying gentle compression. The meter is a good place to start in getting the
proper setting, but it doesn’t necessarily mean that it sounds right. As always, let your ears be your guide.
