stampsosu

Hey guys, I have a few questions for you. I had a car audio store bypass my stock amp and I installed a 4x 50W eclipse amp w/ Polk DX6's in all four doors. It sounds sweet (very loud and clear). But I noticed a problem and I do not know if it is the AMP or something with bypassing the stock amp. I am getting ready to go back to the store tomorrow, but I wanted to get your input first. I noticed that the rear speakers are MUCH LOUDER than the front. At first I thought that maybe the front speakers were still running off the stock amp. So I played around with the amp for awhile, unplugging some of the speakers from the amp to see if they were running off the amp or not. I noticed that they had the REAR Left speaker running to the Front LEFT channel of the amp and the REAR Right speaker running to the Rear LEFT channel of the amp. I finally figured out that the Front Left and Rear Left channels put out MUCH MORE power than the front right and rear right channels. Strange? They had it configured so the back would be a little louder than the front. Had they hooked up the AMP correctly ( the front right going into the front right channel of the amp, and so forth) then the left side of the car would be louder than the right. It is not as noticeable with the rear speakers being a little louder than the front.

I know this post is long, but I hope I explained my situation well....Any thoughts? Is this normal if one bypasses the Stock AMP? Did they do something wrong when bypassing? Do you think they just sold me a used (slightly faulty AMP)? Don't get me wrong, the car sounds great, but if they did something wrong, I would like to know..

thanks

Southbound

Don't apologize for long posts... Mine take the cake! I can't tell you what the problem is, but something DEFINITELY isn't right. As you have described, if they hooked things up correctly (according to the channel labels) you would have a louder left side than the right side. If this was their first wiring configuration and they noticed that fact, and then they "crisscrossed" the wiring to make the rear speakers louder than the fronts.... it seems to me that they probably thought that that would be preferable to the balance problem... BUT I WOULD BET THAT YOU WOULD HAVE A SCREW UP WITH YOUR STEREO IMAGE! You can't crisscross half of the amp without having the stereo image reversed from the front seat to the rear seat. That just sounds bogus to me.

Use your fader and balance controls and see if that is true. Pick some music with some good stereo separation where you can distinctly hear one instrument on one side and some other instrument on the other. Say for instance, if you have piano playing predominantly on the left, and guitar on the right in the FRONT... and when you go to the REAR if the piano is now on the right and the guitar is on the left. THEN YOUR STEREO IMAGERY IS COMPLETELY SCREWED UP! If this is the case, then you MUST go back to them and show them where they went wrong.

The stock headunit can be somewhat difficult to bypass. It uses balanced inputs and outputs with floating grounds. If they somehow chassis grounded one side of the floating balanced line, then you would lose some gain in that channel, because it would become unbalanced and lose half of its gain. This may be what's going on???? Ask them if they TRULY bypassed the headunit amp, or did they come off of the four speaker outputs of the headunit. If they truly bypassed the amplifier section of the stock headunit then they would have taken the feed to the new amp from the TWO preamp outputs. This would probably sound best, but would not allow for the stock fader control to work because their is only ONE left and ONE right preamp output. Does the fader control still work? IF it does, then they fed your new amp from the four speaker lines. In that case, they would probably use LOCS to convert the speaker level out to a line level out to feed the new amp. These LOCs could have their gain messed up and mismatched. I guess they could crisscross the new amps inputs if they ALSO crisscrossed the headunit outputs... That would keep the stereo image correct, but why in the hell they would need to do that makes no sense to me.

Check out how the fader and balance controls work or do not work at this point... and check out the stereo polarity as I described above so that you know whether or not that left audio is being sent to BOTH left speakers, and right audio is being sent to BOTH right speakers. Then go have a chat with them after you have deduced where the faults lie. After you have evaluated your system controls, and levels, and stereo imagery... Explain to them all of the oddities that are going on, and make the clowns install it correctly.

GOOD LUCK!
Southbound

ckNJ

If you really want to test things try to get a Stereophile Test CD a sound level meter. I have Test CD2 and a Radio Shack level meter I use to measure output on my home theatre, so it should be more than enough to get some definitive levels on your speakers.

ckNJ