Please explain mixer connections, equalizers, compressors, and groups.

We were just gifted a very nice sound-mixing board and I am in charge of it. While I can handle the basics I would like a good resource where I can learn what all the terms used in mixing mean. I read the manual that came with it and I still don’t understand the concepts behind hooking the sucker up, what jacks are best to use, what groups and subgroups are, etc. Got an idea for a good resource?

Our monitors and mains go straight from mixer to amp to speakers. Why would you use an equalizer between mixer and amp? Isn’t that what the mixer is for? And what is a compressor used for?

Would I use the grouping to combine several channels into one for say a monitor for just the vocalists?
Pete Hanlon

Reply: I'd recommend the book "Practical Recording Techniques Fourth Edition" available at amazon.com. It covers mixers and mixer operation, as well as sound, signals, mics, mic techniques, effects, digital recording, sound quality, and so on.

Here are the basic mixer connections to make:

You can get by without a graphic equalizer between mixer and amp, especially if your house speakers are really good. However, if you have a graphic equalizer, you use it to flatten the frequency response of the house speakers. Mixer EQ is just for individual instruments and vocals, not for the entire system.

It's also common to use a graphic EQ between the monitor send (aux out) and the monitor-speaker power amp. That EQ is used to reduce the levels of frequencies that feed back. You also can use the graphic EQ to reduce the bassy sound in the monitors caused by microphone proximity effect (the bass boost that occurs when directional mics are used up close).  The monitor signal from the board is pre-EQ, so turning down the bass (low frequencies) on the mic channel does not turn down the bass in the monitor speakers. That's where a graphic EQ can help: turn down frequencies a few dB below 200 Hz or so. Then the monitor speakers won't sound too bassy and muddy.

A compressor is used to reduce the dynamic range of whatever signal you pass through it. For example, a lead vocalist might suddenly sing a very loud note, blasting the listeners. The compressor is an automatic volume control - it turns down loud notes so they don't get too loud. If this isn't a problem in your church, you don't need a compressor.

The groups are for the house speakers, not the monitor speakers. You might assign all the vocal mics to Group 1 (also called subgroup 1 or submix 1). Then you can control the overall level of the vocals with just the group-1 fader. Start with the group fader and master fader about 3/4 up. You don't have to use groups, but some people find it convenient. If you don't use groups, just assign each mic channel to the stereo mix bus (the master stereo output of the console), and turn down all the group faders because they are not being used.

To confuse things, some consoles use Group 1 and Group 2 as the main stereo output channels. Other consoles have groups plus a separate stereo master output channel.

The aux knobs can be used for monitor mixes. I assume that your mixer has several aux channels (aux-1, aux-2, aux-3, etc.) Each aux number is a separate monitor mix, feeding a separate monitor power-amp channel, feeding a separate monitor speaker.

You might use all the aux-1 knobs to set up a monitor mix for the vocalists. Connect aux-1 out to the power-amp channel for the vocalists' monitor speakers. Then use all the aux-2 knobs to set up a monitor mix for the drummer. Connect aux-2 out to the power-amp channel for the drummer's monitor speaker. Use Aux 3 for the piano player, and so on.

For example, let's say the vocalists need to hear only the piano and vocals in their monitor speakers. You would  use all the aux-1 knobs across the console to set up a monitor mix for the vocalists. Turn up the piano channel's aux-1 knob about halfway. Turn up the vocal channels aux-1 knobs about halfway. Turn up the aux-1 master knob (if any) about halfway. Make sure the vocalists can hear the monitor mix, and adjust it according to what they want.

Similarly, suppose the drummer needs to hear only the piano and bass. You might use all the aux-2 knobs across the console to set up a monitor mix for the drummer. Turn up the piano channel's aux-2 knob about halfway. Turn up the bass channel's aux-2 knob about halfway. Turn up the aux-2 master knob (if any) about halfway. Make sure the drummer can hear the monitor mix, and adjust it according to what the drummer wants.