Live Sound Equipment - Mixing Desks

Analogue Desks

The mixing desk that we use in school for live sound is the Behringer Xenyx 3200 (picture to the left). It is a 32 channel mixing desk with 6 aux sends per channel, 4 stereo line outputs and 4 output buses, as well as many more features. This is like most standard live mixing desks, such as the Yamaha MG32/14FX or the Peavey 24FX. Some mixing desks have different features on them that make them distinctively better for live use as oppose to studio use, for instance, a mixing desk with more outputs and auxiliary sends would be better for live use, whereas a mixing desk with MIDI controllers would probably be best for studio use. Desks with more channel inputs would also be preferable over one that has less because the more channel inputs there are, the more instruments/microphones you can have on stage. A mixing desk with say, 8 channels on them will only leave you with 8 possible inputs for microphones/instruments, making it very unpractical for live use. A 32 channel mixing desk would triumph over an 8 channel mixing desk because of the amount of possible inputs available. As well as inputs, a mixing desk would want to have multiple output sends too, allowing multiple amounts of monitors/speakers on stage. The auxiliary sends on a desk would be the main control of the monitors on stage, look at this diagram below:

As you can see by this diagram, the auxiliary send allows you run some external monitors into the desk via an amp going into the mono output of the auxiliary. The monitors are then controlled by the ‘Aux 1’ knob which can be found on all channel input strips, allowing you to adjust the volume of what is going out through the monitors. The more auxiliary outputs that a desk has, the more monitors you can run, so the desk we use in school (Behringer Xenyx 3200) would be very good because it has four mono aux sends, allowing for four sets of monitors on stage. A comparison between the mixing desk in the school recording studio, the Allen and Heath ZED-r16, and the Behringer Xenyx 3200 would be that the ZED-r16 has limited features that make it good for live use. The outstanding features of MIDI controllers, firewire connection and impeccable sound quality mean it triumphs over the Behringer for studio use. The Behringer is far better for live purposes though because it has more auxiliary, FX and main outputs, four different group buses and a maximum of 32 possible channel inputs. The ZED-r16 has only two auxiliary outputs for monitors, one set of main outputs and only 16 channel inputs, making it unpractical for live use. The Behringer has no USB or firewire input setting making it nearly useless for recording purposes.

Another main feature of the Behringer that excels it in the live environment is the four different group buses. What these groups do is they control the volume of a number of channels with just one fader, and the way to send certain channels to a group is by pushing in the group button next to the channels fader. This detailed diagram below shows an exact representation of the desk, explaining how to send channels to a group:

By clicking the button that says ‘group 1-2’, the channel input gets sent to the subgroup output one. By clicking the button that says ‘group 1-2’ on multiple channels, they all get sent to the same subgroup and you can adjust the volume of potentially 32 channels on one fader. A way to use the groups logically is to maybe group all of the drum microphones together, setting the levels first and then sending them to the output. Having control of a whole drum kit on one fader is very useful, because if the whole kit is too loud or too quiet, it makes it easier to adjust the volume accordingly. You could group the whole drum kit on say group 1, then on group 2, 3 or 4, you could control all of the vocal microphones, simply by pressing the relevant button next to the fader. The last button on the channel fader, represented by the diagram above says ‘main’, and that button when pushed in send the channel to the main output. 

Digital Desks
There are many differences between analogue and digital mixing desks, as well as many similarities. For starters, digital desks are far more expensive, due to the added features from analogue, the way the signal goes out the speakers is different, and the amount that you can actually do on them is far more superior over the analogue desk. It works in the same way as an analogue mixer in the way that the microphone gets plugged into an input, someone speaks into it and the signal comes back out again, however on a digital mixer, the signal gets converted from analogue to digital. A digital signal is a lot more clear and sounds better than an analogue signal, which is one feature that separated the digital desk from the analogue. Digital signals are used whenever you are recording using a DAW, it is the exact same process. The signal goes into the DAW as analogue, and gets converted by the DAW, and the digital signals gets sent to the main speakers. A digital desk is a software driven desk, meaning that all of the channels can be controlled by programming into the desk. Like an analogue desk, a digital one uses faders, channel strips, knobs etc. they just have the ability to be programmed and saved. For instance, you can set the levels for a microphone how you want them, get it perfect, and save the setting so you can automatically get that setting up again. This is very useful because you would spend time perfecting the setting, change the fader and knobs around, and still get that perfect setting by just loading it from the desk. Below you will see a picture of a digital desk (the Behringer X32) so you can see what it looks like in comparison to an analogue one:

The specifications of theBehringer X32 includes up to 32 microphone pre-amps with 6 aux inputs, 16 XLR outputs with 6 aux outputs, 25 mix buses complete with 6-band parametric EQ, 8 stereo FX slots for 40 plus effects plug-ins, plus many more.
For a further in depth analysis, clink this link to visit the Behringer website.

This sort of digital mixing desk would be useful for large venues such as the O2 arena in London. The in house mixing console that they use however is the Soundcraft Vi6 digital mixer (click here for more details) and it is a much larger desk than the Behringer, with features including 96 mono inputs, 32 input faders, and 32 fixed send buses. The venue owns two of these mixing consoles, assumingly a spare one just in case, and they only use this mixer for their live performances.