Setting Gains on Self Contained PA Head

[bucephylus]

At our Saturday gig, we had a little bit of on-stage drama in the first set. It began with the typical "band is too loud" complaint as people were eating their dinner. However, what became weird was that we were having a hard time controlling the vocals levels.

The self-contained head is mine. It is a Peavey XR 680. I usually set the individual channels between 12 and 3 o'clock to get them leveled and then bring up the main level to suit the needs.

In this case, due to the restricted space, the head was behind the keys player. He's got good ears and some sound engineering experience; so, that should not have been a problem. However, he was pegging the mains volume and then bringing up the channels to fit. When I mentioned that this might not be the best approach, I got broadsided by both the drummer and keys player (on stage) that I was totally wrong, that mains are always driven full out, I should know better etc.

Some of this is due to other dramas that aren't worth talking about.

Anyhow, I realize that in a power amp / mixer rack it is common to open up the power amp and control from the mixer. But, these self contained heads aren't quite so precision. The individual channel gains aren't as linear or quiet as a good slider. That's why I tend to run them like a bass amp.

So who is right?

In any case, the full on mains approach was producing all kinds of noise, volume fluctuation, feedback etc. because the channel pot was barely coming on before it was too loud. The thing I couldn't understand is that even if the concept makes sense, why get so dogmatic that you keep doing what doesn't work? Anyway, that's band politics. I'm curious how the rest of you might be running your self contained mixers.

[mwm70]

I am not a sound engineer by any stretch, but their approach seems flawed for the exact reasons you experienced. Every situation I have turned volume full out, it has resulted in noise and an inability to control the mix.
I was under the impression that you should always mix the sound then increase the power of the mixed sound as needed.
That is how we go about it with our powered mixer, but again I am not a sound engineer.

[Rick Brienzo]

I always find that if I set the master at a little under 75% and then bring the channels up I get the best results. If my channel gains only get to 2 or 3 than I will bring the master down a little and raise the channel levels.

I think the only rule of thumb is to not let your channel gains go above where your master level is set.
You could possibly get some clipping.

[bucephylus]

Thanks for the feedback. I agree that the individual channels need to be at levels that do not produce clipping. However, Peavey seems, IME, to have engineered these self contained heads so that there is a lot of headspace. Isn't avoiding clipping from the individual channels the ONLY thing that matters? If so, why does it matter where the output gain is?

I understand why people use this approach on the larger component systems. It just seems these self-contained units are designed to work more like a bass amp.

[Dkerwood]

I usually set the master around 50% and see where that gets me while turning up individual channels.

FWIW, I think you're absolutely right, and considering that it's your gear, you should get the last word on it. The higher you push the master volume, the less usable the individual channel gains become. I mean, if your lead singer's mic is feeding back at 2 on his individual gain knob, how on earth can you fine tune that? The answer is to back the master back down and turn the mic up to 5 or 6. Anybody who insists upon wrestling with that tiny bit of usable volume (essentially ON or OFF at that point) is a bit of a fool.

The next time your keys player gives you any static about it (pun intended), ask him to crank his keyboard amp up to ten (or even better, crank his volume on the mixer to ten) and control his overall volume from his keyboard. See how that works out for him.

When I run with my rack gear, I do run my power amp at full power, but I also have compressors protecting my gear from excessive signal from the mixer.

[bucephylus]

Thanks. I received similar input from Wesley R via PM. I think we're on the same page. Thanks all for the input.

[theshadow2001]

What I always thought you do is operate the gains from incoming signals in order to keep the singal levels averaging around unity gain (0 dB)

Then adjust the sliders to get a mix. Keeping the master signal at around 0 to +6dB. Then you use your master faders to adjust the over all volume of the mix.

As a rule of thumb for me anyways. Keep the gains between 10 and 12 o' clock and adjust the faders starting at 0dB. (It helps to mute FOH for this)

Another rule of thumb for me is don't run anything at max. It just doesn't seem like a smart thing to do. That seems to go for any sort of machine really.

Now I'm not 100% on this.So don't quote me on it. Im not a sound engineer. I could say I have engineering experience because I did sound once or twice but that doesn't mean that I know what Im talking about. *cough* *cough* keyboardist *cough* cough*

[theshadow2001]

Here's a quote from an allen and heath 2400 manual. Which can be found here

Mixing with faders or gain controls? There is a technique
used by some operators where they set all the faders to ‘0’ position
and balance the mix using the channel gain controls. We do not
advise this method as the signal to noise ratio and control resolution
can be severely degraded. In addition, it is impossible to mix monitors
from FOH in this way as changes to the gain settings affect the
monitors too.
The correct method is to use GAIN to match the source to the
operating level of the channel for optimum dynamic range, and then
use the FADERS to balance each source into the mix. With correct
system gain structure, prime sources such as vocals would have their
faders operated around ‘0’ while sources low in the mix such as
backing vocals and acoustically loud brass and drums would display
their true contribution with their lower fader positions. This is a much
more visual and accurate way of mixing.

Although the model is a bit away from what you own I'm sure the principles still hold true. Don't use the gains to mix.

Edit: Oops! I jsut googled an image of what you own. Most of what I posted was irrelavent (thought you had a powered desk) My bad. Still though don't run the master up full.