Where to set the amp volume/gain

[Dace]

I apologize if this is a repost, I searched but couldn’t find an answer.

I have read conflicting advice about where to set your amp volume/gain.
Some say turn the amp up as far as it will go to allow full access to the amps power. Others say set it at halfway (the DBX PA+ says to set it at 51%)

Which is correct?


For reference the amp is a GX5

[wallywally]

I set them at 100%. If you are limiting you must do this or find some way to lock them in place so they can't be turned up.

[Dace]

I do limit with a drive rack.

[Bill Fitzmaurice]

I do limit with a drive rack.

Set the amp full, that's the only way to adjust the limiter.

[Dace]

Should I keep the amp at 100% all the time?

[J_Dunavin]

I don't have a limiter, so I set my gain on the amp like this:
With crossovers off, I play a 1K tone and measured the max clean output of my board, EQ, Crossover, with an oscilloscope. (I have to pad the crossover by the way, because the output from the EQ can clip the input. ) I then measured the output of the amp until I reached the predetermined voltage for cabinet it's going to be hooked up to.
It may not be the best, but I know I will not over power my speakers, I have proper gain structure, and my amps run nice and cool.
The gain is about 3/4 ish. Oh and I always do this without the speakers hooked up

[Gregory East]

Should I keep the amp at 100% all the time?

You can have it anywhere you like so long as the limiter has been set with amp at 100%. Running it down from 100% will lower the system noise in the quiet parts but reduce your headroom in the very loud parts. In my experience system noise is very low, not worth worrying about.

Some guys have amps that are way too powerful for their cabs so the loss of headroom in their mixer is unacceptable. The limiter would kick in with only a small part of the faders in play.

Mr Dunhavin is running sound for church groups at modest volume. He has control of the system, full fader control. Even so, I think it's an unacceptable risk to have an amp hooked up unlimited. Accidents happen.

Have look for setting gain, stage, headroom, noise, there will be an article somewhere in the education links.

[Tom Smit]

If no-one ever, ever, ever touched your controls, you could get away with setting the amp volume. However, the safest way is to set the limiter with the amp turned up full, and then adjust the limiter to limit the voltage (sans speakers). This will also prevent a sudden twitch from becoming an "oops".

[doncolga]

If no-one ever, ever, ever touched your controls, you could get away with setting the amp volume. However, the safest way is to set the limiter with the amp turned up full, and then adjust the limiter to limit the voltage (sans speakers). This will also prevent a sudden twitch from becoming an "oops".

+1 I ended up selling my big amp and getting a smaller one because it was much closer to the volts I needed when it was a full power without the signal being completely squashed when the limiter kicked in.

I believe that amp should put you in the ball park of 53 volts to a 4 ohm load, probably per channel...that's a little more than I've got on my Behringer EPQ 1200. I run two Tuba 30's on each side of that amp, one with two 3012lf's and one with two Lab 12's. My limiter engages with not too much gain reduction.

[J_Dunavin]

Gregory East is right... I really do need a limiter.

[Ryan A]

Yup, you do. The only exception I can think of is if your amplifier has a built-in limiting switch AND the maximum voltage that it can put out is less than the speaker is designed for. For example, many Carvin, QSC, and other amps have built-in limiting to prevent clipping.