The main difference between a live mixer and a studio mixer is the absence in the former of monitor channels and the monitor path, since these components are only needed in recording [Recording ] and studio mixing [Mixing ] . To simplify the following description, let's imagine a mixer which fulfills both the functions of a stage mixer and those of a FOH mixer. As we've said, it is possible to create a set of independent mixes for the musicians onstage. These mixes are created as a result of the presence of a greater number of auxiliary sends compared to studio mixers. An average-sized mixer can have more than 10 auxiliary sends, of which some will be used for the effects and the remaining ones will be used for creating the musicians' mixes. [16 ] So, with each channel's auxiliary sends we control the amount of signal present in the mix, whereas the overall volume of each mix will be controlled by the aux send masters. Naturally, depending on the kind of mixer, a set of modules for the manipulation of the signal, such as equalizers, filters, compressors, gates etc. shall be present on each channel. Some mixers, rather than having auxiliary sends, will sometimes have a fader which is similar to groups, in which each fader has the same function as an aux send master. The difference is that a master is piloted by a fader rather than an aux send master potentiometer. Let's also take a closer look at the way the groups are organized; the latter can be of two kinds: normal or VCA. The normal groups work like the groups on studio mixers, namely, that they group into one fader a set of input signals. VCA groups (Voltage Controlled Amplifiers) consist in an extra series of faders each of which controls a series of amplifiers that are present on the input channels, as shown in the following diagram:
In the diagram we can see how in actual fact, the signal in the channel isn't controlled by the variable resistance of the fader, but rather, by an amplifier whose gain is controlled by the fader. In other words, by acting upon the channel's fader we modify the gain of the amplifier whose task it is to control the signal, and not on a simple resistance, as is the case with normal channels. If we then transfer the control of one or more amplifiers present on the channels to a VCA group, the result will be that by acting on the group fader, we will control the level of all the channels that have been assigned to that group.
[16 ] Usually the mixes that are created are in mono, therefore each mix takes up one auxiliary send only. Sometimes it happens that a musician requests a stereo mix in front of him using two monitors.
VCA controls