Turn it up or not?

[midlife]

I have a Crown DC300 for my main power amp. It has L&R gain controls on the front of the amp. I have been told by some in order to get the maximum head room those gain knobs should be run full up regardless of my volume needs (listening levels should be controlled by the preamp gain). What would you do to have it "right"?...........

[SEAWOLF97]

I have a Crown DC300 for my main power amp. It has L&R gain controls on the front of the amp. I have been told by some in order to get the maximum head room those gain knobs should be run full up regardless of my volume needs (listening levels should be controlled by the preamp gain). What would you do to have it "right"?...........

thats the same advise that I got to the same question .... been doing it that way with no problems.

many amps (including some very "high end" ) have no gain control, they just always run wide open.

[midlife]

So too much might just be enough?

[BMWCCA]

It's not correct. They aren't gain controls, they are input attenuators. The simplest explanation is you set them so at the loudest level you play your system your pre-amp volume control is in the "sweet spot" around the three-quarters point, and at "normal" level around the half-way point. This question got asked quite frequently on the Crown forum and was answered by a Crown employee and I re-posted it here. Let me see if I can find the thread:

Here's one mention: http://www.audioheritage.org/vbullet...7&postcount=19

But I think this is the one I was thinking of: http://www.audioheritage.org/vbullet...0&postcount=19

Here's the entire "gain structure" reply from the Crown Forum: http://www.crownaudio.com/forums/ind...indpost&p=4628

[midlife]

It's not correct. They aren't gain controls, they are input attenuators. The simplest explanation is you set them so at the loudest level you play your system your pre-amp volume control is in the "sweet spot" around the three-quarters point, and at "normal" level around the half-way point. This question got asked quite frequently on the Crown forum and was answered by a Crown employee and I re-posted it here. Let me see if I can find the thread:

Here's one mention: http://www.audioheritage.org/vbullet...7&postcount=19

But I think this is the one I was thinking of: http://www.audioheritage.org/vbullet...0&postcount=19

Here's the entire "gain structure" reply from the Crown Forum: http://www.crownaudio.com/forums/ind...indpost&p=4628

I usually try to find the sweet spot among the source (when adjustable), pre-amp and the amp. However I do remember being told that the input attenuators on the DC300 should be run full up to offer the best protection from clipping. Is it a debate or a known quantity??? thanks, every little bit helps, no?

[BMWCCA]

Is it a debate or a known quantity??? thanks, every little bit helps, no?

Uhm, did you read any of the links? Personally, I think I'd trust the Crown rep. But you can do what you want. Pretty much all you can do is introduce more noise. It won't get any louder or produce any more power.

[Allanvh5150]

I heard the same argument a few days ago. No professional in thier right mind would run the Power amps attenuators any less than full. One of the linked articals even goes as far to say that if you run the amps on full you will not be able to get any more from the system.... Regardless of the power that is being used, in a live situation there is ample control from a mixer that is running the masters from about halfway to 0. I have run all the amplifiers that I have ever used on full. If any one is worried about amplifier or mixer noise in a live situation they should get another hobby.

Allan.

[Fred Sanford]

I heard the same argument a few days ago. No professional in thier right mind would run the Power amps attenuators any less than full. One of the linked articals even goes as far to say that if you run the amps on full you will not be able to get any more from the system.... Regardless of the power that is being used, in a live situation there is ample control from a mixer that is running the masters from about halfway to 0. I have run all the amplifiers that I have ever used on full. If any one is worried about amplifier or mixer noise in a live situation they should get another hobby.

Allan.

So...why are there attenuators on pro amps, then? Shouldn't there just be on/off switches?

I generally do as described before- match it to the range I'm using on the fader controls, so that I can make the most of the fader/volume control while introducing the least amount of noise. Sometimes that's max, but here at home it's not (Yamaha P2100s at -16, Crown DC300A at ~7, JBL 6260 at -12, etc.).

But, I guess I'm a professional that's not in his right mind, so take that for what it's worth.

je

[midlife]

Uhm, did you read any of the links? Personally, I think I'd trust the Crown rep. But you can do what you want. Pretty much all you can do is introduce more noise. It won't get any louder or produce any more power.

I get it, in a home environment balance the pre and main gains to the desired output.

[BMWCCA]

:dont-know

I get it, in a home environment balance the pre and main gains to the desired output.

Yeah, but that's really a simplistic method because most home systems don't have the metering necessary to let you know when you've hit zero on the output meters. As Crown says, it's not the amp's output or power you're choking, you're just matching the input to the correct operation range of your pre-amp.

Sort of like the level-matching on a Soundcraftsmen EQ; you don't want to overdrive your pre-amp so you generally cut EQ rather than boost if you don't have level-matching controls and LEDs. With your Crowns you don't want to under-drive your pre-amp because it might not be as quiet in the lower volume-control positions or the highest positions and, since you don't have anything to measure the pre-amp output, you simply set the amp input attenuators to keep the pre-amp in its sweet spot to minimize noise.

Running your power amp wide open won't affect the power amp, but it might cause your pre-amp to run in a volume-control range that isn't optimum. I don't do this for a living and I didn't stay at a Holiday Inn Express last night, either. But I do know there's some reason Crown sells an anti-tamper knob set for their D and PS-series amps so the system engineer can set it where it should be and then keep prying little hands off those controls. $6 a pair, last I ordered any.

FWIW, I've worked with a pro SR engineer for a couple of years now, just helping out, setting up, and running the monitor board mostly. His biggest portable system runs five Crown MacroTechs and those knob positions are clearly marked, and the board's output is set so the main sliders can't go past zero. With the sliders at zero and the amps' attenuators set in the correct postion, the system gain structure is set and the noise floor optimized. You can do this in a rudimentary way for home use by following the instructions given above by the Crown technician.

I'm no expert, obviously, but for all I know, the NZ method of setting gain structure (balls-to-the-walls) could account for why Opimax picked up noise from my Soundcraftsmen EQ using his down-under amps that I don't hear in my 4345 using the same front-end and my bi-amped Crowns with their attenuators set-up properly.

And yes, I'll take my punishment over the air, Mr. Limbaugh.

[hjames]

:dont-know I'm no expert, obviously, but for all I know, the NZ method of setting gain structure (balls-to-the-walls) could account for why Opimax picked up noise from my Soundcraftsmen EQ using his down-under amps that I don't hear in my 4345 using the same front-end and my bi-amped Crowns with their attenuators set-up properly.

And yes, I'll take my punishment over the air, Mr. Limbaugh.

Yep, not only were they from a certain southern country,
but they were located in the basement,
with ins and outs cables run through small holes in the floor!

Literally Down Under!

[SEAWOLF97]

I have tried both ways...

amp gain/attenuators wide open or half way ...big BGW is so quiet that I cud hear no difference. Same on the preamp volume control...so why not have access to all the power that you paid for ?

and on the gain/attenuator question....Phil is prolly right, BUT the manf labels them gain on the units and in manuals.

[Fred Sanford]

I have tried both ways...

amp gain/attenuators wide open or half way ...big BGW is so quiet that I cud hear no difference. Same on the preamp volume control...so why not have access to all the power that you paid for ?

and on the gain/attenuator question....Phil is prolly right, BUT the manf labels them gain on the units and in manuals.

Most of my pro amps are labelled as attenuators- actually the Crown DC300A is the only exception, its labels run 1-8.

As to why not have access to all the power you paid for: I back them down to have more precise control from the fader- if 25% up on the fader is the loudest I'll ever play the very quietest tune on my system, why not bring down the amp's input so that 75% or more of the fader's throw is useful day-to-day? As an example, on my main monitors the amps are brought down -16dB, which makes my main volume knob settings ~2 for quiet, late-night use; 5 for most reference mixing, and ~7-8 for really slamming it. With the amps set wide open, I can't get past 2 or 2.5 and stay in the room comfortably. I much prefer a gradual, linear control.

Another part not mentioned so far is that many times in a pro situation you want hot levels coming out of your mixer (pre) in order to reduces the losses from sending the signal 100' or more to the stage & power amps. The power amp level controls would enable you to set the mixer running at its best range and still balance the house audio. There's also many other uses for the level controls, one being when a signal is split to multiple amps & speakers that you want differing output levels from (or, speakers of differing sensitivity ratings, that you want identical output levels from).

Dunno- I use them all the time, and they're helpful. :dont-know

je

[SEAWOLF97]

There's also many other uses for the level controls, one being when a signal is split to multiple amps & speakers that you want differing output levels from (or, speakers of differing sensitivity ratings, that you want identical output levels from).
je

that is EXACTLY what I do with the 2nd BGW running rear of the room fill speakers (both are coming off the same preamp) ....I dont want them competing with the mains, only for rear fill and run that amp at abt 1/3.

[BMWCCA]

...so why not have access to all the power that you paid for ?

I do. You do, too. Remember, you're not limiting the power, at least in the case of the Crown's input attenuators, but I don't know what BGW calls them. Instead you're dialing back the input level.

There's no way anyone can stay in the room with my bi-amped 4345s if the volume control approached three-o'clock so running it in the normal range of nine-o'clock to one-o'clock I'm reasonably certain I'm not throttling-down the Crowns even with their attenuators at twelve-o'clock high!

Yet another opportunity for one of my well-loved automotive analogies:
Throttle tip-in on most American and Oriental vehicles is immediate if not abrupt. Certainly non-linear—more of a bell curve on the downhill slope. You feel like you have all the power in the world off the line and in the first 25% of throttle travel. On the other hand, those fine German makes have near-linear throttles, or used to. You push the pedal half-way and you've gotten half the available throttle opening. The reason Lexus, among others, do it their way is the uninformed customer thinks the things are rocket ships when they first get in them. BMWs and Mercedes by comparison seem slow off the line unless you give them more "gas". Which one do you think actually allows more control in throttle modulation during cornering, applying power gradually, or in steering the car with the throttle, otherwise known as "driving" the car? GM even used an almost on-off brake application on their cars at one time. I used to scare myself to death driving my grandmother's Impala everytime I hit the brakes! And that was decades before ABS. Scary!!