proper way to set your gains

i remember seeing a post (maybe on here, maybe somewhere else), but i can not seem to find it. anything is appreciated.

Turn gains on amp to min. Turn HU up until you hear distortion. Back HU down a little until distortion goes away. Turn amp gains up until you hear distortion. Back amp gains off a little until distortion goes away. Sit back and enjoy.

Paul

simple way i use to set gains on sub systems properly is to use a Digital MultiMeter.  first find you a cd that has sine waves on it, like some of the dj majic mike,or usaci sq/spl cds.  find a track that plays in the heart of the bass region, like 40 hz.  put cd player on repeat, set all eqs to flat and turn volume up until you can find the peak ac voltage being produced by the rcas.(put one lead of the dmm in the rca and the other lead ground to the outside metal ring) then turn volume back down a little.  hook rcas to amp with gains all the way down and check output at speaker terminals with no speakers hooked up using DC voltage.  when you get DC voltage to .1 that is about 1 %thd.  you can also use the DC setting on the rca outs of the radio.  then you can switch the dmm to read AC voltage on the speaker outputs of the amplifier to figure out approx how much power you are making with approx 1% thd.  remember ac voltage x ac voltage / speaker impedance=watts. so if your getting 50volts ac @ 4 ohms your amp is producing 625 watts .  50*50=2500/4=625.  this little trick will get you in the ballpark on setting gains without having to invest in an oscilliscope and keep your subs from getting to much dc voltage in the voice coil which=fried stinky woofer.

-------------

ooops forgot to clarify that you are adjusting the gains on the amps when you attach dmm to amp speaker outputs

-------------

i'm stoned as a mofo right now, and the last one sounds pretty f**king crazy, yet, you have a feeling that you simply can not go wrong with that sort of testing. i might try Francious70's method for the time being.

good idea

-------------

would you recommend that way for setting up amps for the mid and tweets?

stevdart--it is going to vary by the settings available on your dmm, go to the lowest setting that will let you read .1 v dc and that should be the one. 

wesley 444--it is hard to accomplish this on mids/tweets because you will have to find a sine wave generating program for the higher freqs and send signal to your car via laptop or some musical material that will play the freq you want constantly.  with some patience you can do it by repeating tracks of your fav songs, if you choose that route, make sure you have a remote for your deck or a friend who likes to push cd 'skip back' alot

good luck fellas!

-------------

what freq would you recommend setting the amps to.... I'm running type x 6.5 components, front and rear

btw, i found the read i was looking for:

So many people have their amp gains set wrong, and to be honest setting them by ear is quite a crapshoot. Doing it properly with a multimeter is actually quite simple.


Here's how you do it:

Set head unit volume to 3/4 of maximum. Turn off all eqs/presets in the head unit.

DISCONNECT SPEAKERS

P = Power in watts
I = Current in amperes
R = Resistance in ohms (effectively the nominal impedance)
V = Potential in volts (Voltage)

Knowns:
Resistance (nominal impedance of your speakers)
Power (desired wattage)

Unknowns:
Voltage (we'll measure this)
Current

Formulas:
P = I*V (formula for power)
V = I*R (Ohm's law)

So after a little substitution to get Voltage in terms of simply power and resistance we get

V = square_root(P*R)

So, for example, say you have a 4 ohm load presented to a 150 watt amp.

V = square_root(150*4) = 24.5 volts

This means you should increase the gain until you read 24.5 volts AC on the speaker outputs of your amplifier.

As a source, use a sine wave recorded at 0db at a frequency within the range you intend to amplify. You can generate tones in cool edit or use a program such as NCH tone generator. (credit for NCH to imtfox, IIRC)

Additionally, you could use a scope to actually check if the signal is clipping, but I'm not going to get into that here as I doubt very few people have access to that type of equipment.

UPDATE:
After playing around with the following programs:
Cool Edit 200
Test Tone Generator
NCH Tone generator
It seems that NCH tone generator does not save files at 0db. The tones generated by NCH were noticably quieter than tones generated by the other two programs, which seemed to be the same level.

Yes, the 0 db reference level is the major problem I had using Frequency Generator, too.  That's why I allow that the program is good for setting crossovers, not gains.  There have been some major players here who have argued that without a scope, using a DMM for setting gain is more of a crapshoot than the ear method (varying impedances at different freqs, etc.)  Taking it all into consideration, I say that the person who does both is most likely to be accurate in the long run.

thanks for the help newtone and stevdart

I set my mrd-1000 on my type x 10 today and my front type x 6.5 components on a mrv-t320 the way you suggested....

boy does it impress me.... can't wait till my other set of x components come in