Auxiliary Sends
Next on the console we come to the Auxiliary (Aux) sends (figure 10). Aux sends are the first output signal that we encounter on the mixing console. Up to this point on the mixing console we have been solely discussing input signals. While the difference between an input signal and output signal may seem self explanatory, there are some things that can get a little confusing. An input signal is pretty straight forward. If you have a microphone that is plugged into your console and you are talking or playing into that microphone, it is sending a signal to the console’s input. You can now adjust the gain, EQ, etc., of the input signal that is being received from stage. However, when you get to your auxes, you are able to take the input signal and send it to multiple places. So, while you have one input signal, you can have multiple output locations/paths for that input signal to travel to. For example, in my old church which had about 75 people in the congregation, we had our vocals sent to 3 different locations. Using the aux outputs, we sent them to an external effects processing unit, to our monitor locations, and to the front of house. Later when I was at Cherry Hills, we had up to 10-14 mixes for our bigger productions where we would send a single input signal to up to 14 different outputs for In-Ear-Monitor (IEM)/headphone mixes, choir wedges, intercom sends, and more.
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Aux sends can be used for many different things and are quite versatile. Aux sends will take the input signal of that channel and send it somewhere else other than to the main output of the console. In most cases, especially analog consoles, you will still be able to utilize the input channel fader to control the output of the signal to your main stereo/mono output. Aux sends, in a way, will duplicate that signal and allow it to be received somewhere else.
Figure 10
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Going a little further down the console, there is a button labeled “Pre/Post” (Figure 10). This is a toggle feature that allows your aux sends to be in one of two modes, “pre-fader” or “post-fader.” Pre-fader means that the movement of your main input fader which feeds your main output is not going to change the level of the aux sends. Post-fader means that the movement of your input fader is going to change the level of the sends. If you turn it up for the house, it will get louder in the sends. Pre-fader is most often used when using the aux sends as monitor mixes. This is because you want to be able to have different mixes for the band and for the house and have them isolated from each other. Ideally you would set a monitor mix for your band and not have it change unless they request a change, or unless they change it themselves on an Aviom/similar tool or application.
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On the Allen and Heath and other consoles, there are two of these Pre/Post buttons. One is located underneath aux 4 and another is located underneath aux 6. If your console is laid out this way, this simply allows you to chose the pre/post function for the previous grouping of auxes. The first button, located under aux 4, determines the pre/post for auxes 1-4. The second button, located under aux 6, determines the pre/post for auxes 5-6. This can be useful if you want to have one group of auxes set to pre-fader and another set to post-fader. For example, with onboard or outboard effects processing, some people like to process their effects post-fader. This allows the engineer to have effects come on when the fader is brought up and go off when it is brought down. Further, aux groups could be built post fader to follow the front of house mix changes, but to tweak the mix slightly for another source, like broadcast. Personally, I run almost all of my auxes as a pre fader level to be able to create separation from my aux sends and my front of house mix, but there have been times that I have used post fader to help build certain effects or mixes which, while separate from the front of house mix in certain ways, are linked to the fader movement. Last, some mixing console manufacturers will swap the Aux and EQ sections, having the auxes before the EQ. However, more often than not, I’ve seen the auxes located after the EQ section.