Amp Gain Calculation Question

Grimmjoww

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Apr 18, 2021
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If you have an amp that produces well over rated power, do you set gain for the power in rms that it can actually produce. Or do you set gain for what it's rated? If I have a 1k amp that produces 1.5k easily, do I set my voltage for the 1k and it will just throw more or set it for 1.5k? The amp dynos I watch are a little confusing on how they get their numbers. Thanks
 

tommydh

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Mar 31, 2012
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If I understand what you're asking correctly, it should be based more on distortion threshold more so than rated power. My thought is once you set up your load and start there the next steps would to start setting gains. Ideally using a DD-1 or similar you will set everything to get optimum performance. The amp dyno I'm most familiar with is the Meade design one. I know there are others out there and there is a way to clamp the amp and determine power output.
 

mat3833

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Mar 12, 2008
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If you have an amp that produces well over rated power, do you set gain for the power in rms that it can actually produce. Or do you set gain for what it's rated? If I have a 1k amp that produces 1.5k easily, do I set my voltage for the 1k and it will just throw more or set it for 1.5k? The amp dynos I watch are a little confusing on how they get their numbers. Thanks
OK, buckle up and get ready for some learnin!

Most reputable amps have a "rated" power, a "dynamic" power, and an "actual" power. I'm going to use your 1k amp as an example with arbitrary numbers for simplicity.

Say you watch a "dyno" video of your amp model and at 1 ohm it dynos at 1500w on a "certified" run and 1800w on a "burst" run.

Your amp is as follows:
"rated" at 1000w
"actual" at 1500w
"dynamic or burst" at 1800w.

Now, these numbers will vary from amp to amp. No 2 amps are the same. Dynamic numbers are a bit of a grey area. It's an approximation of the power an amp can produce on music, but should mostly be disregarded.

So in your case if your subs can take the extra power, there is no harm in setting your gains to the "actual" power of 1500w. However, if your amp only makes 1450w of clean power, you can run into issues. You can get a cheap o-scope to verify your amps clean output power.

Personally, I set my amps to their rated power. I know they will make more, but an extra 300w isn't much at all. You need double the power to be 3db louder. To me, it's not worth the potential cooked speakers trying to run anything right on the edge of what it is capable of.

Matt
 

Buck

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There’s a ton of factors to this. How good your box is can determine how much power, both mechanically and thermally, your sub can take.

What frequency do you plan to use 1000 or 1500w? Amp gains set to 1000w @ 40 hz in a ported box will not put out 1000w at 30 or 60 hz. If the amp does, that’s magical.

I tune by ear and sometimes by smell; usually I try to avoid the smell part, just depends on how much output you want.

Your sub might take 1500w on a mild temp day, but it might not on a summer or winter day, and not due to heat, but changes in the speed of sound due to temperature differences.

If you drive to the mountains from the sea, your box tuning will change, so if you set your gains for 1000w at 40 hz at sea level, then it’s not going to be that in the mountains.

And that’s why I tune by ear. You’d need like a quantum computer to perfectly set gains for all possible scenarios.
 
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Grimmjoww

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Apr 18, 2021
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Very good info, thanks Buck. That was what I was thinking as well on the tuning parameters one would use to account the correct voltage for the gain to watts. I will just tune this little rascal at 750w to be safe and get a bigger amp. I can see how this is going to turn out already though, one 10 isn't going to be enough lol.
 

1aespinoza

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May 22, 2013
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Very good info, thanks Buck. That was what I was thinking as well on the tuning parameters one would use to account the correct voltage for the gain to watts. I will just tune this little rascal at 750w to be safe and get a bigger amp. I can see how this is going to turn out already though, one 10 isn't going to be enough lol.
I have been using a ported 10" sub for a while now. I have found it to be quite pleasing on all categories. Usually I switch up every 3-4 months and rotate my cache of subs, but this little 10, just hits the spot.
 
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Grimmjoww

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Apr 18, 2021
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I have been using a ported 10" sub for a while now. I have found it to be quite pleasing on all categories. Usually I switch up every 3-4 months and rotate my cache of subs, but this little 10, just hits the spot.
Dont get me wrong, it hits pretty hard, I would guess high 130's. And it will be good for a while. It also sounds very good, I mean really good. It will hit even harder after it loosens up and I build the bigger box I'm sure. But it would be even better if I found another to match LOL.
 
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ThxOne

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Very good info, thanks Buck. That was what I was thinking as well on the tuning parameters one would use to account the correct voltage for the gain to watts. I will just tune this little rascal at 750w to be safe and get a bigger amp. I can see how this is going to turn out already though, one 10 isn't going to be enough lol.
One 10 is never enough lol. I am missing my JBL 12's.
 
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mat3833

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