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Basic Sound - Monitor mixing

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The purpose of monitors are very different to that of the front-of-house mix which has to concentrate on ensuring the audience hear the best sound possible. Monitors are needed in medium and large venues to ensure that the musicians can hear themselves and the instruments around them, allowing accurate singing and playing. The monitor mix is just for the musicians and so can be completely different to that mixed for the main front-of-house speakers. Although FoH and monitor mixes can be produced from a single desk, the two roles are generally divided between two desks and engineers, allowing each to concentrate on their own area.

Different speakers

As can be seen from the diagram above, there are a number of different speakers used on stage for monitor purposes. The wedge speakers provide a concentrated area of sound and are ideal for musicians which don't move around much. By using them in pairs, an area several metres in length and width can be covered.
The side fills provide a coverage of the whole stage and can be used to provide monitor coverage on spaces where wedge speakers aren't used. They are most useful for providing backing-track coverage for dancers.
Drum fills are specific speakers used to provide the drummer with monitor sound and are usually more powerful than the wedges since they need to be heard over the drum kit itself.

Desk

Since we have a large number of speakers, all pointing at different musicians, we need an equally large number of different mixes. Imagine a sound desk with 30 channels, each with a dozen faders: a bit large! Instead of using large faders, monitor desks use small dials such as that found on the auxiliary controls. These act as channel faders, summing the monitor mixes onto seperate faders to give overall volume controls.
When using a FoH desk instead of a monitor desk, most engineers use the auxiliary controls, set to pre-fade mode, to produce the large number of monitor mixes required.

Feedback

This is the great problem with monitors; since the speakers are pointing at the stage where all the microphones are, a feedback loop can be easily set up. There are a number of things that can be done to reduce the chances of feedback:

Mute any microphones not in use
Try to reduce the volume of the monitors as much as possible
Position the microphones away from the monitor speakers
Try not to boost frequencies using the desk EQ, just cut them
Use a graphic equaliser

Graphic equaliser

This piece of equipment splits the sound into a large number of frequency bands (usually 31) of which the individual levels can be altered. This allows you to accurately cut or boost specific frequencies and tailor the overall sound exactly as you want it.

Since feedback generally occurs at a few specific frequencies, cutting out these frequencies from the mix will allow you to turn the overall volume up. This will usually help considerably but there are limits: eventually you get to the point where almost every frequency feeds back simultaneously. The graphic equaliser is set up after the desk and before the amplifier and in a monitor rig, it is set-up by a process called ‘ringing-out’.

How to ring-out monitors

Set up the monitor equipment, including microphones on stage and graphic equalisers inserted between the desk and amplifiers
Send the monitor mixes through to the monitor speakers
Set all the graphic EQ controls to their central position (0dB)
Turn up the amplifier volume up until feedback just starts occurring
Turn the amplifier volume down slightly so that it is just below the feedback threshold
Adjust the graphic EQ frequency gain controls one at a time, boosting it to maximum
If a frequency feeds back, then reduce it to below zero
If a frequency doesn’t feed back, set the gain back to 0dB
Move onto the next frequency and repeat for all the frequency bands

General tips during the soundcheck

Into the unknown: Not all bands have used monitors before and not all bands understand what they do. Take your time, find out how much the band knows and if they aren’t aware of the use of monitors, explain their purpose.
Less is more: Because of feedback restrictions, simply turning the volume up is a dangerous business. If a musician can’t hear something, try turning down everything else in the mix. Likewise, a musician doesn’t generally need to hear every single instrument on stage. A simple mix will lead to a cleaner sound on stage and a reduction in feedback.
Speaking speakers: Speakers produce sound, musicians need to hear sounds. The most common problem with musicians not being able to hear monitors is the fact that the speaker is not pointing correctly towards them. Get away from that desk, over to the stage, and shift them speakers!
A general mix: Sorry for all you musicians reading this, but when somebody says they want a ‘general mix’ or ‘a bit of everything’ then its clear that they don’t know what they want. If this happens, don’t give them anything in their mix, play a song and then check what they can and can’t hear. Remember that they don’t necessarily need to hear everything on stage.
Practise makes perfect: Setting up monitors isn’t a mathematical equation, the only way you’ll know what to change is to get the band to play a song and find out what it sounds like.
Make an appearance: Whilst the band is playing, jump up on stage an actually take a listen for yourself. This will give you a good idea of the situation and allow you to talk to the musicians as they play.
Notes: Get some paper and a pen, this allows you to write down what the band want in each monitor and enables you to write down all the settings after the band is happy.
Dialogue: Talk to the band, have a chat, make it a two-way process. Remember that you’re working together for the same result. At the end of the soundcheck, ask each member whether he/she’s happy with their monitors. If they are, you’ve done your job perfectly!

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