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B: The Initial Gain Stage
The initial gain stage occurs right at the input connector. It lets you adjust the signal level as it enters the mixer. It is
usually controlled by a knob with any of a number of labels: trim, gain, level, input, mic, line—it depends on the
manufacturer of the console. In any case, it is usually the first knob at the top of the input strip. Sometimes the initial
gain stage is a switch (–60, –10, 0), although these type of mixers probably don’t have insert points.
Sometimes, on larger consoles, there are attenuators, mic/line switches, polarity inverters and/or low-cut filters.
These can also be considered part of the initial gain stage.
The initial gain stage is important because it affects the signal before it reaches the insert point.
C: PFL and Solo
Many people who operate sound equipment use a feature on their console called “PFL” (pre-fade listen) or “Solo.”
These buttons (at the bottom of the input strip) usually activate a meter, which allows the sound operator to adjust the
initial gain stage. As with many audio related scenarios, this method of setting the initial gain stage may or may not be
appropriate depending on many variables. However, since an insert’s sending level is dependant on the initial gain
stage (i.e., prefader), PFL should be checked, especially if you hear noise or distortion.
D: Insert Point
This is it—the insert point. When nothing is connected to this jack, the signal passes unaffected down the input strip to
the rest of the mixer. But when you insert a signal processor, the signal is diverted out of the mixer, processed, then
returned to the insert point. This requires a special cable and connector. See Cables and Connectors for Insert Points.
E: Fader
The input faders, located at the bottom of each input strip, adjust the level of the signal going to the main mix bus.
Some mixers use a knob instead of a sliding control.
This fader does not affect the signal at the insert point. In fact, that is the reason the AuxPander connects to the insert
point—so that you do not have to worry about the rest of the mixing console settings affecting the mix of the AuxPand-
er outputs.
CABLES AND CONNECTORS FOR INSERT POINTS
Two-Connector Insert Points
Two-connector insert points are generally found on larger, more expensive mixing consoles. One connector, labeled
“insert send,” connects to the input of your processor, while the other, labeled “insert return,” connects to the output.
Two-connector insert points allow the signal to remain balanced. Balanced signals use two conductors for one audio
signal—a method that increases the signal’s resistance to electromagnetic interference. This is advantageous in ap-
plications with longer cable runs.
Balanced insert points require a shielded, two-conductor cable and three-conductor connectors (two for the audio
signal and one for the shield or sleeve). This includes 1/4” tip–ring–sleeve (TRS) and XLR connectors (larger, 3-pin
professional audio connectors used for microphones).
Single-Connector Insert Points
This type of insert point has the advantage of being compact, since just one connector carries both the insert send and
insert return. This is usually a
1
/
4
” tip–ring–sleeve (TRS) connector, like that used for balanced signals. The tip and the
ring conductors carry the insert send and insert return signals. The sleeve conductor is the “common ground” for the
send and return.
