Owner`s manual

page 8
SIDE CHAIN CONTROL
For connecting a side chain signal to the m502, you need a 500 series rack which has a provision for
an auxiliary input to the module via pin 7 (Radial Engineering Workhorse or the Purple Audio Sweet
Ten win again in our book). Connect an unbalanced side chain signal via the tip of a 1/4” TRS cable to
the aux in. This signal will be available for side chain input via pin 7. This pin must also be switched on
at the m502’s PC board DIP switch location S5 SW2, and the S4 SW1 (page 9) must be switched o,
which will disconnect the link internal audio path from the side chain input.
Normally, the compressor’s side chain circuit uses the internal audio signal to trigger its response.
But in side chain mode, the side chain circuit uses the external signal input to determine how the
compressor responds.
Examples of using an external side chain signal include ducking and de-essing. Ducking is an eect
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 they are speaking. It involves routing
a separate signal from a microphone (or any other source) into the side chain input of the m502. This
signal is what the compressor reacts to and thereby would typically reduce (or duck) the level of the
main signal in the m502. 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 side chain 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 side chain 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
top to bottom, 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 reected 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 and hopefully thereby rocking out. If only the
rst 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.
SETTING THE OUTPUT CONTROL
The OUTPUT control provides 20dB of variable level control at the output of the m502. After setting
your desired input and threshold levels, you can set the over all output of the m502 with this control.
Use the OUTPUT to properly match to the input of your converter, interface or whatever is next in your
signal path. Also, your signal level may have been be reduced by heavy compression settings, so the
OUTPUT control can also be used to provide makeup gain.