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gain setting for car amp
gain setting for car amp
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Old 15th March 2019, 08:55 AM   #1
audiophase is offline audiophase
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Join Date: Mar 2019
Default gain setting for car amp

hi,

i just joint this site , i wanted to know how to control gain with DMM, and somebody pls explained to me about gain how to go about it, this is my question:

1) how to setting gain on 1 gain on 2 channel amp
2) how to setting gain on 2 gain on 2 channel amp

anybody pls ?
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Old 15th March 2019, 09:09 AM   #2
Perry Babin is offline Perry Babin  United States
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Set the gains to where the amp reaches clipping at about 3/4 of the volume control's range.

If you want to match left and right, you can use the meter to do so.

Too many people make setting the gains far more complicated than it needs to be. There are too many variables to have one way to set them to make everyone happy.
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Old 18th March 2019, 07:10 AM   #3
audiophase is offline audiophase
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Unhappy Gain setting on car amp

Thanks Parry Babin and you are right that people make setting the gains far more complicated than it needs and that is why im keep asking and joint this forum coz still not clear how to do it.

anybody who is professional in this topic pls give me some good advice .

my question is if im using DMM to set my gain , is this the correct way:-
1) say 50w/chl x 2 chl total is 100w x 4ohm is 400 and square root of 400 is 20vac, now if the amp have 1 gain how to set it ,and if the amp have 2 gains how to set it

2) how to set gain if 2 chl amp that have 2 gains when bridge mono , or bridge mono 2 chl amp with only 1 gain

pls help it really confused me.
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Old 18th March 2019, 07:30 AM   #4
Perry Babin is offline Perry Babin  United States
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You can't use the voltage in the real world. Unless you have a scope, you don't know where the amp clips. Even with a scope, the voltage from the battery, the speaker load or even the frequency of the majority of the signal will make using the assumed voltage useless.

Using voltage alone to set gains almost never results in satisfactory output levels since you're generally setting the amp so that it never clips. Unless you only listen the NPR, you're never likely to have enough power to set the gains so that the amp will never clip.

When an amp is bridged, it's good to have the channels close but if they're off by a small amount, it's no big deal. In most amps with a single gain control for two channels, the gain won't track exactly.

If you want to get them exact with a dual gain amp, drive the same signal into both channels and measure the AC voltage across each channel and adjust the gains until they match.


Others should offer their opinions.
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Old 18th March 2019, 08:07 AM   #5
Gioba is offline Gioba  Italy
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Important to see the context, i think.
Because not possible take a standard method for any situation.
It depend from the component before the amp, or the set before.

For example, the HU, or Hu + DSP, or HU + preamp + electronic crossover ecc.
Each situation have her solution, for to set the amp gain it's necessary a not too much lower signal, for to preserve the dinamic response, but not too much highest signal, for to remain out of clipping.

So it depend from the upstream signal substantially.
I agree that people make setting the gains far more complicated than it needs to be.
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Old Yesterday, 07:18 AM   #6
audiophase is offline audiophase
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Thanks to all that respond to me, I only have DMM to get some idea on my gain setting so pls let know is this the way :-

Now, what I really want to know is this the way to calculate the Vac on each gain :-
1) 4 chl amp 65watt /chl with 2 gain - 1st chl 65x 2 chl = 130w x 4 ohm = 520 ,square root of 520 is 22.8vac on chl 1 gain ,so on chl 2 also 22.8vac ....pls is this the way?

2) 2 chl amp wih 2 gain bridge total 365 watt - 365w x 4 ohm= 1460vac , square root of 1460 is 38.20vac so do I need to divide 38.20vac by 2 for each gain ......19.10vac each gain .. bt if this is a 2chl amp with single gain then i just use 38.20vac......pls help

Pls whoever really know this stuff ....pls explained to me ...thanks to all again
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Old Yesterday, 08:21 AM   #7
Perry Babin is offline Perry Babin  United States
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You can use Ohm's/Joule's law to calculate voltage but what are you going to do after you have the voltage?
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