Gain Setting - What exactly does it do?

[Jtsky 10+ year member]

How exactly does setting the gain effect how much power the amp puts out? Does it effect the wattage? If so, I am assuming amps wattage would be measured with the gain all the way up, correct? Or are they measured as high as they can go without clipping? Again, if it does effect the wattage, how much of a difference in wattage is it usually between as high as it can go (w/o clipping) and as low as it can go?

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[Raven 10+ year member]

All amps are tested with an unclipped input signal. How much power the amp pushes won't change between 0% gain and 100% gain, because the input signal is adjusted to fit the gain.

 

[Jtsky 10+ year member]

Okay, now I am really confused. I thought the amp is what does the clipping. Are there some input sources that an amp will not clip? If the amp's power output does not change between %0 and %100 gain then why do people say to "watch their gains" when they are overpowering a sub?

 

[SSS 18734 5,000+ posts]

The gain is the amplifier's input sensitivity. For example, if you are sending an amplifier a 2v input signal, the gains will have to be set much higher than if you feed it a 6v signal, but you will still get the same amount of power out of the amp.

 

[Jtsky 10+ year member]

So lets say that you have a HU with 2v pre-outs, with gains set accordingly. You then switch to a HU with 5v pre-outs. Obviously your gains will be to high, but would the amp be putting out more power (even if it is clipped)?

Now lets say you have that same HU with the 5v pre-outs and gains set properly. Wouldn't that mean you would have less power output than that same HU and the gains set higher, just now it is not clipping right?

One more thing, lets say you have an amplifier that puts out 400 wrms x 1 @ 4 ohms. You have a sub that will put a 4 ohm load on the amp, but wants only 300 wrms. Would you be able to turn your gains down enough to have the amp only put out 300 wrms, or does gain even effect wattage?

(Just to let you know, I am not in any of these situations. I am just trying to further my knowledge and this is one of the things I don't completely understand.)

 

[SSS 18734 5,000+ posts]

So lets say that you have a HU with 2v pre-outs, with gains set accordingly. You then switch to a HU with 5v pre-outs. Obviously your gains will be to high, but would the amp be putting out more power (even if it is clipped)?
Now lets say you have that same HU with the 5v pre-outs and gains set properly. Wouldn't that mean you would have less power output than that same HU and the gains set higher, just now it is not clipping right?

One more thing, lets say you have an amplifier that puts out 400 wrms x 1 @ 4 ohms. You have a sub that will put a 4 ohm load on the amp, but wants only 300 wrms. Would you be able to turn your gains down enough to have the amp only put out 300 wrms, or does gain even effect wattage?

(Just to let you know, I am not in any of these situations. I am just trying to further my knowledge and this is one of the things I don't completely understand.)

if you switch out the head units without touching the gain settings, the amplifier still sensitive to 2 volts, it will reach clipping faster because of the increased signal. So basically, it will seem louder, but it will put out maximum power at a lesser volume level.

And yes, you can set a 400 watt amplifier to do 300 watts by turning the gains down.

 

[AVSTANG02]

We need amps that have active gains that adjust themselves accordingly.

and then if you want to under or over power, it allows you to fine tune from that point.

 

[Jtsky 10+ year member]

So about how much more or less power (mainly want to know about less) could you use the gains to make your amp give out?

Also, if you have that 400 wrms amp like I said earlier, and set the gains so that it only puts out 300 wrms, is it going to draw less power, or will it still draw as much power as it would running at 400 wrms (I know dimming isn't really a concern with only 400 wrms but this is just an example)?

 

[SSS 18734 5,000+ posts]

yes it will draw less power if you turn the gains down.

 

[Jtsky 10+ year member]

Alright, now one last thing.

Lets say that you have like a 1200w amp and some subs that only wanted like 400w. Would you be able to turn the gains down that far? And the amp would only draw enough power for the 400w correct, so basicly no dimming?

 

[SSS 18734 5,000+ posts]

Alright, now one last thing.
Lets say that you have like a 1200w amp and some subs that only wanted like 400w. Would you be able to turn the gains down that far? And the amp would only draw enough power for the 400w correct, so basicly no dimming?

depends on the pre-out voltage of your head unit, and the range your gain settings will do. If you have a 4v pre-out head unit, and the lowest sensitivity the amp will do is 4v, you wont be able to get less out of the amp. But remember, its pretty rare that an amp will push its full power at any given time, unless you like to listen to test tones during your drive to work. And you can also adjust a lot of settings from your head unit to make the amp put out less power.

 

[Jtsky 10+ year member]

Alright, I guess that answers everything. Thanks for the help.

 

[SSS 18734 5,000+ posts]

Not true ... You can easily reduce power output on a 4 volt head unit by turning down the volume and/or sub level ...

You forgot to quote the rest of my post, smarty... so I'll do it for you

But remember, its pretty rare that an amp will push its full power at any given time, unless you like to listen to test tones during your drive to work. And you can also adjust a lot of settings from your head unit to make the amp put out less power.

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