GAINING UNDERSTANDING: The Proper Use Of The Gain Control
The first circuit in
the console that the source signal "sees", is the preamp. It will
always be the first adjustment. Since the preamp feeds to all other
signal chains, this first circuit adjustment must be set correctly for every
device connected to the console. This will insure a low noise-level while
remaining free of distortion.
that varies the level of the signal being sent into the preamp is labeled:
gain, trim, input sensitivity, or attenuator. These are all words for the
same control. (We will call it gain.) If the gain is set too low, than all
other parts of the signal chain must be set higher to compensate. The result
is the addition of unnecessary noise. If the gain is set too high than the
input signal could overdrive the preamp and clip the signal and induce
distortion. Neither of these is desirable.
Gain could be
thought of as a window. At the top of the window is distortion, clipping,
peaking. At the bottom of the window is noise, hiss, static. We do not want
to let the signal get into the distortion. We also do not want to let the
signal get buried in the noise. What we want is for the signal to fluctuate
freely within the window.
setting of this control will vary with each microphone, and user. This is
because each mic has a slightly different output level and each user has a
slightly different volume level into the microphone. This is not a problem
since this is exactly the purpose of a gain control. The same holds true for
line input sources such as tape decks, wireless mics, keyboards, etc...
Once all the
input gains have been set, the channel faders will have a nominal starting
point. Of course throughout an event the individual fader locations will
change to compensate for the artistic needs of the mix, but the gain
settings will remain constant unless the primary use of the input source (mic,
tape, etc...) changes.
is a step by step check list for setting the console gain on a properly
calibrated sound system.
- The first step is to see
that all connections and routing assignments are properly made.
- With the gain levels turned
down, (full counter clockwise) have the performer begin singing or playing.
- Bring the console master fader
and/or sub group fader to their nominal position (usually "0" or
- Bring the channel fader to the
nominal position ( usually "0" or "-10" dB)
- Slowly begin increasing the
gain until the volume level through the main speaker system is appropriate
for the performance.
- Next bring the monitor levels
to their nominal position ( this may be difficult to determine if the system
is not properly calibrated.) This will be a clean and appropriate starting
place for the monitor systems (adjust as needed by the performer.)
- Make any necessary eq and
reverb adjustments for the most natural sound.
- Now you have a clean,
undistorted and appropriately leveled natural sounding signal you can mix
for an outstanding performance.
If you will follow this procedure at the beginning of
every rehearsal session, you will have a better blend, happier musicians,
and usually a faster sound check. It also lets everyone know that you take
your job seriously. (You're not just foolin' around back there.)
If you do not
follow this procedure you will not know exactly how loud any one source is
in relation to the other sources and the monitor mix can easily be
"whacked out." Don't worry though, the folks on stage will let you
know when their mix is not just right.
© 1998 Jordan Audio Consultants