Setting my gain with a DMM for my amps

Mithrandir · Post by **Mithrandir** » Sat Jun 17, 2006 3:33 pm

Ok I have a US Acoustics USB2150 and a JBL Powervalve 1200.1. I cannot find the voltages like JL Audio has listed for their amps. Is there anyway to find em or should I just try setting the gain by ear?

NViejeP · Post by **NViejeP** » Sat Jun 17, 2006 3:40 pm

the equation for voltage is

The Square root of (ohm load x rms)

Mithrandir · Post by **Mithrandir** » Sat Jun 17, 2006 3:51 pm

NViejeP wrote:the equation for voltage is
The Square root of (ohm load x rms)

oh, so thats ohmload x rms x 2 (squared is x2 or x3?)

oh you said square root, bah i hate math

/me googles it

Mithrandir · Post by **Mithrandir** » Sat Jun 17, 2006 4:00 pm

ok i found the square root, now am I looking for the rms per channel or the total rms or what? And say im running 2 dvc subs at a 4 ohm total load on a mono amp, would the rms I use be what the amp puts out at a 4 ohm or would it be cut in half since their are 2 subs or whatever.

Robert Wollenberg · Post by **Robert Wollenberg** » Sun Jun 18, 2006 6:15 pm

http://www.usacoustics.com/2004/usb2150%20specs.htm

ohms (4) times rms (450) = 1800

The squar root of that is 42.43

Now, that rms ratting is at 12.9 volts. I'm guessing the amp will put out more while the vehicle is running. Maybe not. Anyway ... that's roughly what you're looking for.

Mithrandir · Post by **Mithrandir** » Sun Jun 18, 2006 6:25 pm

ok, well I took it 150 rms per channel so I just went for like 24.4 volts ac and even with it that high, it was retardedly loud and drowned out my subs.