Hi SL,
I've been researching for weeks now and finally decided on a amp and subwoofer. However I am still fuzzy on the whole matching the impedance of the amp and sub. I ordered a Rockford fosgate P-500-2, its output is :

4ohms: 125 watts x 2 chan
2ohms: 250 watts x 2 chan
bridged to 4ohms: 500watts x 1 chan

I'll be pairing it up with a single Focal 30A1 subwoofer that can handle 4ohms, 250watts rms.

If I use 4ohms straight off the amp I will be underpowering it by 50%. But if I bridge it then I'll overpower it by 200%. I've read somewhere that I can only achieve 2ohms when I use a pair of subs, but I will only use one.

Can someone help me with the wiring please? I'd hate to ruin such a nice subwoofer by making a mistake.

Thanks in advance!

 

you need to look at the specs of the amp to see if its producing RMS or peak power. if its peak power when bridged, then you should be fine with running the subs.

however, based on setup, fosgate amps usually produce a lot of power. i would be wary about blowing out your sub.

here's a great tutorial

http://www.jlaudio.com/header/Suppor...Drivers/287544

 

Thanks that helped, those numbers are actually rms. I think it'll match perfectly with the sub.... well hopefully. I've already have an 8 gauge in my car already, you think I could get away with that? fosgate recomends 4 gauge, but usually 8 gauge is good enough for anything about 600w rms or less right?

 

Yea unfortunately with the sub and amp combo you really don't have a good way to hook it up. You either have to decide to run it at half power and potentially blow the sub by underpowering it or you can hook it up bridged and overpower it and potentially blow it that way. the rockford amps don't over rate their equipment like most other companies do. If it's rated at 500 bridged it most likely will push that.

NOW I don't know a lot about focal subwoofers but it may be over rated at 250rms so you might be fine powering it at 125rms. In all honesty you should be fine either way as long as you tune the amp to not over drive the sub or with it at 125 tune it so that the amp is not clipping when you turn it up loud.