Setting Gain levels for Mixer, Crossover, Power Amps

[Phantasm]

I'm sure there's a thread that covers this, but I'm not sure what to search for to find it.

 

I know how to set levels on each channel of the mixer with the PFL. I know I want to keep the lights in the green, or "below 0db" on the PFL meter.

 

I know that when I'm mixing on the board, I want to try to stay in the green or "at or below 0db" on the output level meter. (I'm using a Peavey RQ2314 mixer.)

 

Now, when I get out of the mixer... I go to a DBX 234XL. There are no lights on the crossover to tell what my level is going in. I see that there's an input gain/cut and for each of the frequency outputs there's also an output gain/cut. How do I know how to set these to get maximum signal without going over?

 

Then we reach the power amps. These are QSC and there's a light to let me know the amp's getting signal and a red light to warn about clipping. The clip light never comes on right now. How do I tell what level of signal I'm sending to the power amp?

 

I'm sure there's a good way to do this, just I don't know what it is just yet. I do know that I clicked the input gain up very slightly on both channels of the DBX a few shows ago and the system volume increased quite a bit and we don't have to push the faders on the board up quite so high.

 

So can anyone point me in the right direction?

[imnotded]

Are you needing to be louder? I've always liked the, "if it ain't broke, don't fix it" mentality. But if your asking just to know then thats another story.

[agedhorse]

Set the input levels on your amp to 6dB below full sensitivity. That will be close enough gain structure-wise for all practical purposes.

[Unalaska]

Sounds good on the mixer side, are you using an EQ? I'd highly recommend a 31band EQ before the crossover. There are a couple of schools of thought on gain structure. People from both sides have their veiws are for sure will express them, so this will most likely be a long thread...

 

But since I'm here:

EQ input at 0dB (unity) when there is one.

Low out at +3 to +6 (depends greatly on speakers/amp used, YMMV)

X-over at 100hz

High out at 0dB

Amps turned wide open

 

at this point the system should make no noise, no hissing/buzzing. If there are issues then it's gain structure in or before the mixer and needs to be addressed there.

[Phantasm]

 

Are you needing to be louder? I've always liked the, "if it ain't broke, don't fix it" mentality. But if your asking just to know then thats another story.

 

 

I'm trying to get the signal as good as possible going into the amps to make sure that there's no desire to push the mixer harder, causing channels to start to distort. We were having to push the mixer a little too hard to get the volume we were looking for, and we have the wattage/speakers needed to get the volume. I noticed a few clicks on the input into the crossover let us put the faders lower and stay at 0db or lower, and this cleaned up the sound IMO.

 

I just wasn't sure how to set the gain structure on the crossover since there are no meters. There are no +4db/-10db input switches on the crossover, either.

[Phantasm]

 

Sounds good on the mixer side, are you using an EQ? I'd highly recommend a 31band EQ before the crossover. There are a couple of schools of thought on gain structure. People from both sides have their veiws are for sure will express them, so this will most likely be a long thread... But since I'm here: EQ input at 0dB (unity) when there is one. Low out at +3 to +6 (depends greatly on speakers/amp used, YMMV) X-over at 100hz High out at 0dB Amps turned wide open at this point the system should make no noise, no hissing/buzzing. If there are issues then it's gain structure in or before the mixer and needs to be addressed there.

 

 

Thanks for taking the time to type that up. Right now we are using very similar settings, but I do have the subs set to 0db as well. We spent some time subjectively listening and decided that's where it sounded the most balanced, tops and bottoms.

 

We don't have a graphic EQ. At some point we're considering it, but right now we find that the PA sound pretty good without one. We also noticed a lot of the venues we play that DO have one, if we bypass it the PA sounds much better! We're after a graphic for monitors first, because we have had success killing feedback with them.

 

In many ways we feel that in most cases if the mains are so loud that we've got feedback issues in the mains, we're probably too loud for the job anyway. Since we adopted this philosophy, we noticed we get a lot more folks staying all night and a lot more girls dancing up near the stage!

 

I've been trying to think of how to put a meter between the board and the crossover, then between the crossover and the power amps. Or, just some way to measure the signal. Maybe a voltmeter would work? i could compare the signal out of the board to the signal coming out of the crossover to see if they match.

[agedhorse]

You do not need to worry about metering. If you run your amp sensitivities at -6dB from full, you will still have over 12dB of headroom before your drive electronics clip.

 

You are way overthinking this.

 

There is so much latitude when you operate things close to nominal 0dB that a few dB one way or the other makes no difference.

[Phantasm]

 

You do not need to worry about metering. If you run your amp sensitivities at -6dB from full, you will still have over 12dB of headroom before your drive electronics clip. You are way overthinking this. There is so much latitude when you operate things close to nominal 0dB that a few dB one way or the other makes no difference.

 

 

Thanks, we'll try this for the show Monday!