Ok my brother-in-law has a Rockford Fosgate P18S4 sub (4 ohm) and a Direct Xtreme amp. The manual for the amp says it is a 2 channel amp and that at 4 ohms each channel will put out 55 watts RMS, and at 2 ohms, each channel will put out 80 watts RMS.
What would the RMS wattage be if we bridged the channels? And what would happen if we added another sub (same exact kind) and wired it in parallel to create a 2 ohm load? What RMS wattage would we see then? And would we damage the amp?
since you have a 4 ohm you can only run it at 2 ohms for now. so you will theoretically be running 80 watts (prob lower) to the subwoofer...
if you added another sub, make sure you get a 4 ohm sub so you can wire it down to 1 or 4 ohms. My rec. is to get a new amp since it barely puts out any power.
and you cant bridge the amp unless its bridgeable... is it?
With one 4 ohm sub that amp will bridge to 160w. A 2nd 4 ohm sub wouldn't be of much help. You can't bridge a standard 2 ch amp down to 2 ohms. You'd be stuck with one sub per channel at 55x2. You'd probably get more output from the one sub getting 160w.
If you were to add a 2nd sub the ideal amp would be a mono that's 400-500w at 2 ohms. The Kicker zx400.1 comes to mind. The Alpine mrp-m500 would do a good job too.