Hi,
I know the accepted way to set gains is by listening for audible distortion, then turning down a hair, but I recently purchased a multimeter in hopes of getting a somewhat more accurate method without spending 500 bucks for an oscilloscope.
I'm using JBL GTO14001 (rated 1500x1 @ 2ohms) for my subs, a pair of 2 ohm (nominal) DVC 12"s (Idmax, re = 2.8 ohms with coils in paralell, FS 20.2).
According to my calculations, the multimeter should read about 55 volts AC when the amplifier is making 1500 watts @ 2 ohms.
The problem of course with this technique is that the subwoofers' impedence varies depending on the frequency. The resonance of my subs in my sealed enclosure should be about 46hz (1.3 ft^3 per sub). It's my understanding the impedence should be highest at this frequency, so naturally if I try to get 55 volts at 46hz I will probably be clipping 20 an 80hz like there's no tomorrow.
So I set my gains to give me 55 volts at 20hz. The problem is, I'd only get 13-20 volts or so on the rest of my frequencies from 25-80hz when I did this. Apparantly the impedence is much lower at 20 due to the IDmaxs' FS.
Next I set the gains to give me 55 volts at 60hz. This gives me good outupt from 25-80hz, but now he amp tries to put out 65 volts at 25hz and I'm too scared to even try playing it at 20hz.
What frequency should I use to set my gains in this fashion? I think it's safe to say my amp is unregulated. Should I use a happy medium between 20hz and 60hz setting? Should I just stay with the 60hz and make sure never to play any 0db sine waves under 25hz?
PS: I also get about a 1 volt DC voltage drop in vehicle power (14 to 13 volts) when I play the 25hz 0 db sine wave with 65 volt AC output from the amp. Also I left my Head Unit volme at 45/62 when setting the gains.
