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

Oh my god, do I feel stupid now... perhaps I should've looked in my own fscking trunk before posting that cry for help.

After all, perhaps I could be a victim of the standard installer-thought-he-was-too-smart-for-the-manual-and-therefore-ignored-the-directions-to-attach-supplied-grounding-rca-cords-to-amp...

Hmm, what are these extra cords lying around back here?

So, I spent all of 60 seconds detaching the leads from the empeg to the amp and inserting the grounding leads inline and attaching the grounds to the amp, and... voila! Distortion is gone, front and rear channels sound great! I guess I'll have to send a nasty letter to the installer's boss. Especially since I pointed out the goundling leads to him and explained their significance. Of course, the quality of the rest of the installation was so high I can hardly complain.

Thanks, empeg, for the great product, and thanks, community, for this wonderful resource. Now I just have to figure out how to keep that single 10 inch sub from shaking my poor Altima to pieces :)

I was just reading your post thinking 'no floating ground' (I had the same problem) but you beat me to it :-)

I'll just have to look somewhere else to do my 'good deed of the day'

Geoff
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Saving hard for a Mark 2...