Gain Setting Tutorial

[i like guns 10+ year member]

Question: If you did this with a multimeter then with an o-scope would there still be a lot of gain left to be turned up without clipping? Could someone test this maybe?

 

[dkguitarist 5,000+ posts]

Question: If you did this with a multimeter then with an o-scope would there still be a lot of gain left to be turned up without clipping? Could someone test this maybe?

even playing music you'll hardly see that rms anyways. if you turn it up more, the amp will start distorting/clipping.

 

[Gurileck 10+ year member]

I am trying to do this with a RF P4002 amp hooked up to a pair of RF T1652S's. I am using the 1kHz tone @ 0db and I am measuring one channel, correct? The problem is even with the gain way up, I am getting only 14 or so V.

using the formula the speakers are 100W RMS ea @ 4 Ohm so that's 20V I should be shooting for, right?

And that is just what they are rated, they are actually 181W RMS @ 4 Ohm which using the formula should get me somewhere around 26V.

So what is going wrong?

 

[dkguitarist 5,000+ posts]

I am trying to do this with a RF P4002 amp hooked up to a pair of RF T1652S's. I am using the 1kHz tone @ 0db and I am measuring one channel, correct? The problem is even with the gain way up, I am getting only 14 or so V.using the formula the speakers are 100W RMS ea @ 4 Ohm so that's 20V I should be shooting for, right?

And that is just what they are rated, they are actually 181W RMS @ 4 Ohm which using the formula should get me somewhere around 26V.

So what is going wrong?

how are you measuring the resistance?

if it's a multi channel amp, i'd imagine you'd measure it like it was "bridged"??

how is the dmm set? and how is your hu set, any bass bost on? any filters on (on the amp? hp/lp?).

 

[Gurileck 10+ year member]

What do you mean by measuring the resistance?

I don't know what dmm is but the HU is at volume of 15 (max I listen to) w/o bass boost. Amps high and low pass are off.

I measure the positive and negetive terminal of the left or +/- of right. (Either produces the same number)

 

[talon2nr7588 10+ year member]

where can i get a cd with the sine wave tone?

 

[Gurileck 10+ year member]

Figured out what the dmm is, it's set to AC Current.

 

[Decipha 10+ year member]

congrats

if you need any tones just PM me i can make any you need

 

[remltr 10+ year member]

hello,

New to the forum,lots of great info here! This probably has been beaten to death but here it goes. I have a jvc kd-lh910 HU. Alpine mrp-f250 4channel and an mtx 3001. Alpine is running 2 4x6 plates in the front and 2 6x9's in the rear.MTX is bridged running a single Alpine 10"type R in a Bazzoka tube. So, I turn up the HU to a volume that I would normally listen to, set EQ in the HU flat. Hu also has a high pwr/low pwr amp gain control( low pwr vol is 0-30 high pwr vol is 0-50) but I assume that it is not in use due to the fact that I am using rca line outs for the front, rear and sub out. Turn gain on CH 1+2 to minimum setting. Turn up gain on CH 1+2 until I reach the desired voltage 12.649. I do the same with CH 3+4. What do I set the filters to on the amp? Off/hp/lp on 1+2 and 3+4? What do I set crossover for 1+2/3+4 they go from 50-400Hz? for a test tone for the 4 channels do I use a 1khz tone? After this is set will playing with the EQ in the HU affect my voltage readings? Now on with the sub. The MTX has a remote gain(plug in),gain, subsonic filter on/off,freq and bass boost. I read that I should turn the remote gain to max. My HU has freq setting for the sub also 155hz,85hz and 55hz. It also has a sub output control goes from mute(0) to 8. What do I set the HU at? After setting up the HU what should I do with the amp?Turn remote gain to full then what what do I set SS filter freq and BB at? After this is all set then I turn up the amp gain to desired voltage 24.494. To set sub amp I use a50Hz test tone? I know its a long post and for you Gurus out there probaly a silly post but I would really appreciate some help. Just want to get the best sound out of what I have.

Thanks

 

[OoMesKoO 10+ year member]

Maybe im retarded, but for some reason, everytime i use the formula, i get some ungodly number. My amplifier is the BX1500D 1500x1 @ 1ohm. with 3 SVC 4 ohm drivers. 1.37 ohm load. Can someone help me out?

 

[xpl0it 10+ year member]

I'll be running a Hifonics XX Colossus II wich realistically is about 3400-3800 watts depending on voltage. Tuan told me this one is rated at 3800, but I'm not sure if he meant 14.4v or 13.8v. Anybody have info on the efficiency of this amplifier? I know when setting the gains if I go by 3400 watts it'll be about 82.46 volts on the dimm, but if it's rated at 3800 should I go by that? Or should I go by what the amplifier will do at 12.5v?(3200+ watts) Thanks!

 

[luvinthebass 5,000+ posts]

ok i want 250 watts out of my amp, it's a lightning audio B4.250.2 2 channel amp and i have it bridged so i figured the voltage i need is 31.6 AC volts to get that 250 watts and i didn't even come close, best i could get was 29.5 AC volts and that equals 217.5 watts rounded up...218 watts. and i used a 50 hz test tone and my bass boost on max and it also has a 50 hz frequency boost and my head unit volume was on 22/30 and it was on the EQ Super Bass which is what i use and to get that 29.5 AC i had to have the gain on max, guess this amp is overrated and how come when i was playin music the AC voltage i was gettin was like 15 AC-22 AC, does that mean my amp will put out 218 watts at taht volume number anytime, i'm confused, and yes it's a pioneer head unit. is all that figuring AC volts correct? cuz i know the formula and i'm pretty sure i'm right.

 

[PollyCranopolis 10+ year member]

I've read where other members are claiming the DMM method is inaccurate and does little to prevent clipping. I myself have used this method and am ending up turning my gains up VERY high on the amp to reach the desired voltage. Can anyone comment?

 

[Decado 10+ year member]

I've read where other members are claiming the DMM method is inaccurate and does little to prevent clipping. I myself have used this method and am ending up turning my gains up VERY high on the amp to reach the desired voltage. Can anyone comment?

It's fairly accurate, just not as accurate as an oscilloscope. How far your gains are up is irrelevant, as long as you get the desired voltage, how far up or down the gain is is dependant on the output voltage of your head unit.

 

[DBfan187 5,000+ posts]

I tested a few Pioneer CD players preouts the other day. With all processing off, the front/rear preouts all clipped @ volume 61/62.