Running the PA amps hot

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NYMorningstar

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I know it's not optimal but I'm starting to see it as pretty common. The volume knobs are just attenuators anyhow so it kinda makes sense to get your power from the amps built for power.

How many of you guys run them maxed out or do you get some of your gain from the boards?
 
By "hot," I assume you mean at full output. Nothing wrong with that if you have a well-designed/balanced system, whereby power amps and speakers are well matched. Nothing less than optimal about doing that. You are basically right in thinking that the volume knobs on power amps (when they have 'em) are attenuators.

We normally run power amps at about 80%-100% of available volume, depending on the space size and needs, when we are at the board, and control volume from there. I do not understand your question about "getting some... gain from the boards;" it seems inconsistant with the rest of your post- the board can only pre-amp the signal, so if power amp is turned down (or has a lower max. wattage) you can only do so much with the slider or gain control on the board.

When we install amps in rehearsal rooms, we tend to pull off amp volume a bit- amps are usually installed/mounted as to be inaccessable to room renters, this allows us to have some control over how hard the speakers are driven.
 
I always run the amps at about 80% and for the life of me this morning I can't remember why!

Let me get another cup of coffee and see if I can jump start my brain ..... Takes more and more coffee every year that goes by.
 
Now I remember ..... no wait, that was before the invention of electricity. Still working on it.
 
Not sure I understand the question, my amps (3 in the rack) are always on full I adjust the level of output via the board - this doesn't mean I'm driving them flat out - they are responding to the levels they are being sent. My amps are matched to the speakers (near enough) not sure I'd run like this if I had eg a 2k per side amp and 300watt speakers. Lots of things effect the amount of signal the amp gets BTW and the worst offender is the EQ's if your running them (I hate smiley faces) :)
 
I generally run power amps input levels wide open and control from the board.
 
Dimed all the time. Them knobs ain't for volume control.
 
I got it!
Dang thought I had it.

You know I just bring the amps up to the max and then back off just a bit for head room ..... I guess.
 
moresound said:
I got it!
Dang thought I had it.

You know I just bring the amps up to the max and then back off just a bit for head room ..... I guess.
Click to expand...

The only pro in the room and he don't remember why he does it. Great. We're fucked.
 
I had wine for dinner and I'm off to the hot tub to boil off the alcohol.

I'll be right as rain in the morning ...... I hope.
 
I had a huge argument with this other techie. I always run amps at max. He was saying that you should go through each part of the system and optimise the signal path, then set the levels on the power amps for the right volume in the venue. There is merit in his argument. For one, it is a way of maximising signal to noise ratio. However, with current gear being so quiet these days, I rarely have a problem with noise.

However, I have been in some venues where there is so much power available that I have only a narrow range of fader travel to work with before it gets unbearably loud. In those instances, I've wound down the power amps to make the desk easier to work.

Most of the time, though, it's everything full up, and it all works fine.
 
gecko zzed said:
I had a huge argument with this other techie. I always run amps at max. He was saying that you should go through each part of the system and optimise the signal path, then set the levels on the power amps for the right volume in the venue. There is merit in his argument. For one, it is a way of maximising signal to noise ratio. However, with current gear being so quiet these days, I rarely have a problem with noise.

However, I have been in some venues where there is so much power available that I have only a narrow range of fader travel to work with before it gets unbearably loud. In those instances, I've wound down the power amps to make the desk easier to work.

Most of the time, though, it's everything full up, and it all works fine.
Click to expand...
I was in the same argument but I'm siding with running them at max. It's good to have the power when you need it at the desk, routine is good especially in a teaching environment and like you said the noise if any is minimal
 
gecko zzed said:
... He was saying that you should go through each part of the system and optimise the signal path, then set the levels on the power amps for the right volume in the venue...
Click to expand...

1. I often do not have the time for such precision- there are usually much more important things to do.
2. Rarely if ever a problem- gecko is right, most gear has low enough a noise floor; when noise creeps in, it's usually a mix-up in the gear somewhere.
3. Even when I would have time to do this, it's usually after the system is set and I'm just waiting for the show to start. At those rare times, I'd rather do anything other than tweak a system that's working just fine.

But, in spite of the fact that I rarely go through all that trouble unless I am being paid, I apparently am not a pro, so what do I know?:rolleyes:
 
Amps should be at max or just a hair backed off .... then use the volume in the cross over to balance the lows, mids, highs for even temperament of the system.
Then go for it at the FOH.
 
moresound said:
Amps should be at max or just a hair backed off .... then use the volume in the cross over to balance the lows, mids, highs for even temperament of the system.
Then go for it at the FOH.
Click to expand...
yep ..... the only exception I could see would be if you had the situation gekko described. Where, with the amps up, you had the faders way down so tiny movements made huge changes. I have seen that.
In that case I'd pull the amps down until I had some fader travel.
 
gecko zzed said:
I had a huge argument with this other techie. I always run amps at max. He was saying that you should go through each part of the system and optimise the signal path, then set the levels on the power amps for the right volume in the venue. There is merit in his argument. For one, it is a way of maximising signal to noise ratio. However, with current gear being so quiet these days, I rarely have a problem with noise.

However, I have been in some venues where there is so much power available that I have only a narrow range of fader travel to work with before it gets unbearably loud. In those instances, I've wound down the power amps to make the desk easier to work.

Most of the time, though, it's everything full up, and it all works fine.
Click to expand...

There is more than one right way to do this. I tend towards hot amps for a very simple reason - My Crown amp does not have an attenuator. i run the monitors and sometimes the subs through this amp. The mains are adjustable Mackie powered cabs (SRM450s). I always set the trim on those at about 75% (at 3:00 or 3/4 turn) unless I'm outdoors or in a small room.

Where I try to work with gain staging, though, is mic preamp and board channel gain - the preamps are moderately hot, the eq is usually in the negative range to be subtractive, and I try to keep the channel gain somewhere in the middle. Board gain is in the lower 1/3. This can still be too hot at times, so I use an outboard compressor on the mains as the last guard, so to speak, with attenuation. With a BBS Maxcom unit I can shut down the whole system with one finger, without messing with any of the board settings.

The other thing I try to stay on top of is during the evening, as the crowd builds and things get wilder, is headroom erosion. Usually both the band and the crowd gets appreciably louder during the evening. I find that on occasion I will pull down every channel gain, maybe 20% and raise the board gain a hair. I'll be getting the same overall gain without using up channel headroom to do it.
 
Good thread. We just bought our pa about a month ago and need it for a show tomorrow. I will take all this into consideration when setting up. At this point I think I'll run the amps at about 80% and work the faders accordingly. It's a pretty small venue.
 
If you have a rack of identical amps, or at least amps with the same gain, then you can use the output trims of the digital speaker processor to control the balance of the levels with repeatable precision. So if you have to swap out an amp on a pass band you don't have to remember where you had the knobs, you just max it out.

Plus, if you can't put you amp rack away from public hands, say at a bar gig, running the amps wide open prevents any drunk patrons from turning them up.
 
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