This is a quick post about pre and post fader settings for aux sends/ mix sends.
On every input channel (vocal, keyboard, guitar…) we have the option of selecting if we would like the aux sends/ mix sends to be pre-fader or post-fader. An aux send/ mix send takes the signal from that channel and sends it somewhere else. This may be to an Aviom, a floor wedge, or to a FX unit (reverb, delay).
If the aux/mix send is set as pre-fader, this means that the signal will be rerouted before it hits the input fader. As you change the input fader to increase, we’ll say, the vocal in the house mix, the fader will not adjust the level/volume of the aux. send. Pre-fader is what you want to use for Avioms and wedge monitors. This way you will not change the volume for the musician/singer on stage.
Post-fader takes the signal and routes through the main channel fader. So, as you change your input fader on the vocal it will also change the volume for the aux/ mix send. This is bad for monitors. If you want to get a lot of dirty looks from singers and musicians run your aux/ mix sends in post-fader. Where you would use post-fader aux sends/ mix sends is when sending signal to an Effects Unit (Reverb, Delay). In this situation we want the signal sent to the effects unit to change as you lower or increase the volume (level) on the input fader. The reason for this is simple. When we run effects we always bring back the ‘effected’ signal back to a channel on the board that is different from the original input, in this case a vocal. We want the level of our ‘effected’ vocal, which is in a different channel, to increase and decrease with the fader movements we make on the vocal channel. Otherwise we would have to make the same fader adjustments on the FX channel as we make on the input channel (vocal).
The typical rule is this. When using an Aux send, set it to ‘pre’ when you are using that aux for monitoring (avioms or wedges). When you are using an Aux to send a signal to an effects unit use ‘post’ fader.
An example that was getting us into trouble. We use pre-service music for all of our services. This music is also sent to the avioms and to places like the mezzanine in the auditorium. The Aux/ Mix send for the mezzanine was set to ‘pre-fader’ which means that even though the music was being turned down on the input fader, if it was not muted or turned off on the CD player, music continued to go to the mezzanine. In this situation we want the Aux/ Mix send to the mezzanine to be post-fader, so that fader moves will turn down the music in the event that the sound engineer forgets to mute or stop the CD music right away.
Aux= Auxillary Mix, this is the term used on analog boards (sanctuary) and on the Midas consoles.
Mix Send= is what they are called on the Yamaha console in the auditorium