setting gain with DMM

Darthness · Post by **Darthness** » Mon Apr 24, 2006 12:14 pm

i went out and bought a DMM from radio shack the other day.. just a little $20 one, will that work? i want to try and set my gain the right way, on my hifonics amp. what exactly do i do?

Ryan from Ohio · Post by **Ryan from Ohio** » Mon Apr 24, 2006 3:18 pm

I think its high time for an FAQ for setting the gains with a DMM.

I will see if I can do one if its already not done

Darthness · Post by **Darthness** » Mon Apr 24, 2006 6:07 pm

damn i forgot to check the faqs for one.. that'd make me look like an ass if its there :P

joeyc · Post by **joeyc** » Mon Apr 24, 2006 6:11 pm

Darthness · Post by **Darthness** » Mon Apr 24, 2006 6:24 pm

digital multimeter.

ridr4lif · Post by **ridr4lif** » Mon Apr 24, 2006 6:35 pm

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Cant wait for updates. Ive always wondered the same thing.

Bwcad1 · Post by **Bwcad1** » Mon Apr 24, 2006 6:37 pm

take the dmm leads plug them into the speaker leads. measure voltage.

Darthness · Post by **Darthness** » Mon Apr 24, 2006 6:45 pm

and frmo there i'm just going assume that i adjust the gain until my head unit's output matches ?

Bwcad1 · Post by **Bwcad1** » Mon Apr 24, 2006 6:57 pm

nah thers more 2 it wait till john kiki or geo answers! they can do it without me fin it up lol

phthisis · Post by **phthisis** » Mon Apr 24, 2006 9:11 pm

I believe that you will want the multimeter to measure the ac voltage from the amp. To find what voltage you will need to set it at you take the sqrt(rms of amp at ohm load*ohm load presented). voltage=sqrt(rms*ohm load). So if your amp is putting out 200 watts rms at 2 ohms you would set the gain at 20 volts. sqrt(200*2)=20. You will want to use around a 50hz test tone recorded at 0db.
http://mobile.jlaudio.com/support_pages.php?page_id=143 There is a good tutorial of how to do it.