Hi. So I just tried reading the entire BBS and didn't find any posts describing trouble like what I'm experiencing, so here goes.

I took my 1996 Nissan Altima SE down to Tweeter Etc today to have the installation done. They pulled out the factory head unit and speakers, and put in the empeg, an Alpine F353 amp with Boston Accoustics Rally Series speakers all around (RX87s up front, RX67s in the rear, RS110B sub in the trunk).

Of course, there were problems :(

I can't detect any alternator noise, and there is only the slightest bit of "digital" noise during bootup, but then it appears to go away.

At low volumes, music sounds fine. The problem is that as soon as I turn up the volume (above, oh, 1/4 of the way up) there is an incredible amount of distortion in the sound whenever there is a moderate amount of "mid-frequencies" present. i.e. plain old bass comes through fine, and plain old highs come through fine, and when there are just bass notes and high notes, everything seems fine. But when midrange sounds come into play (e.g. vocals, guitar, piano), everything sounds distorted. It is more pronounced with music containing "real" instruments- pure electronica seems to escape a lot of the distortion.

The distortion is also definately more noticeable in the rear channels than in the front. If I turn the fade all the way forward, then the distortion is, well, just distortion. But if I move the fade all the way back, then I can hardly hear anything (just a little distortion and hardly any sound).

The guy at Tweeter who did the install said that he swapped the front/rear outputs and the problem went with them, i.e. after the swap, it was the front channels that sounded worse and the rears were much better. He said it sounded like the empeg was overdriving the amp, but he turned the gain all the way down and slowly brought it back up, but the noise was noticeable at all levels.

Since I know, well, nothing about car audio, I'm at a loss. Does this sound like a familiar problem to someone, and is there an "oh duh, you forgot to do X" solution? If so, I have a tiny bit of electronics experience and am willing to experiment a little with grounds or whatnot. Or, am I stuck trying to find a more knowledgeable technician to fix this?

Thanks in advance for any advice you can give.

Brandt Kurowski
empeg 00224