Clipping.....You had the gain turned up too high. The gain is not a volume knob. It is a knob to adjust the amp to accept the input voltage from your HU so that the amp puts out a nice unclipped signal to your speakers.
Once you turn your gains up too high, you start to get square waveforms instead of sine waves going to your sub, and they don't do good things.
I'd read some gain setting tutorials before putting another sub in.
Ok, thanks for the explanation, I thought thats what I did, next time I try this I'm gonna see if I can do it with an oscope so that way I know whats going on and I dont have to do it by the dmm which didnt want to cooperate.
not really, I have never used a DMM to set gains. I do it by ear, then again after 13yrs in car audio im used to it, lol. Just make sure the gains are set good, you got a dirty signal and killed it....
I'm not sure, but you could possibly get Fi to recone it.....Or sell it to someone else that would want to go through the trouble.
I'm not sure if that sub would be worth it or not though. I'm not too familiar with the 7000 series eclipse subs. If it was one of my old eclipse Ti's, I'd be having them reconed, though.
Anyways.....Good luck with getting some bump back in your car.