Hi, I currently have two 12" MTX Thunder6000 subs being powered by a Rockford Fosgate 500S amplifier. Right now it is perfect because the 500S makes 2x250W rms, which is the max for these subs. I plan on replacing these two with an Infinity Perfect 12.1 subwoofer, which can handle only 350W RMS. (I am looking for better sound quality, and the sensitivity of the 12.1 more than compensates for losing a driver.) So with the amplifier bridged into it, I will be pushing 150W too much. How do I know when to back it off so I don't damage the subwoofer?
get a different amp. If you get the 2 Ohm or DVC version of that Infinity 12", it'll present a 2 Ohm load to the amp, so a JBL BP300.1 would work just fine, giving you 300 watts to the sub, for about $135 US
I think what I might do is stay with the amp I have, the set the volume to where I can just barely stand it and set the gains on the amp so that the sub doesn't bottom out.
Another thought, while I'm asking questions, are the Infinity Perfects as effeicient as they say they are? Will it be louder than my two MTX's? By what I figure, the Perfects have a 96 dB efficiency rating, and the MTX's have 87 dB so 87 dB x 2 = 90 dB so the Perfect _should_ be louder. I'm sure that the quality will be better, though. But maybe I should buy two Perfects and use the 500S until I can get a bigger one?
note: gains don't affect the power output of the amplifier. don't use them as a volume control. gains need to be set to balance the input voltages from the line level source.
Don't pay that much attention to efficiency @ 1W @ 1M. That measurement is misleading, and only relevant when the total amp power is less than 100 watts RMS. At high excursion with larger amps, efficiency goes out the window. Now, that being said, the Infinity sub is a much better sub than MTX's 6k series, though you're still losing 3dB or so by going from two subs to one.