The channel output module controls the level and routing of the channel signal after it has gone through the input and EQ sections. Selector buttons allow a combination of routing. Buttons labels 1-2, 3-4, etc. route the signal to the board's eight group outputs, where they may be routed to separate speakers, or used to create a stereo mix in another board section. The master levels for group outputs are usually found as a separate bank of faders on the right side of the mixing console (see next page).
The Stereo or L-R selector routes the signal to the Left/Right or Stereo Mix output, usually controlled by a single master fader (color-coded red on Tascam digital boards) to the right of the group output faders. The Stereo bus would be used primarily in a two-channel listening environment, or with a headphone mixdown. It may be also to control sub levels, since the other eight channels are feeding the eight surround speakers.
The channel fader (the white vertical sliding tab) controls the level of output of the channel signal being routed into any of the master outputs selected and the level of signal to the effects sends if they are set to post-fader. These are usually calibrated in dB or VU (volume units). Faders are for the most part logarithmic, so they correspond with dB and the way we hear. If they were linear, as the fader were steadily lowered, the rate of the fade would be slower and slower in our perception.
The U stands for unity gain, the level at which the signal reaches the fader. 0 dB or 0 VU is designed to equal a gain of +4 dBu, which as mentioned earlier, corresponds to pro gear line level. Above the U, additional strength (positive gain) is added to the signal. It is important to watch your channel meters when adding gain, because if a signal comes into the channel at 100% or you add additional energy through EQ, more than likely, you channel output will clip and distort. Remember, approximately every 6 dB is a doubling of amplitude. Below unity should be marked as negative dB, all the way down to -infinity (∞) or silence.
Some boards include a PFL or pre-fader listen button in this section to allow auditioning the channel signal, normally post-EQ, but at full level, not attenuated or boosted by the channel fader. This is really helpful in live-sound reinforcement situations where one might want to monitor the incoming signal on headphones, but not disturb the pre-set fader level. PFL is most often routed to the monitor bus by default, but BE CAREFUL when enabling PFL if the channel is routed to speakers, as it may be. Boards like the Yamaha 01v96 don't have a PFL button, but allow the solo button to act as PFL when choosing pre-fader on the solo setup page.