how to troubleshoot low volume one side?

[Powder]

My system has cerwin vega components in front Qform kicks with 6X9's in rear tray with a 10" sub w/box in rear seat. Two amps, one for the sub and a 4 channel for the front/rear speakers and a near new Pioneer head unit.
Problem is hardly any volume coming from passenger side kick panel speakers no matter what I do to balance/fade the head unit or tweak gain on the amp. System worked fine, I think, before new engine project and nothing was used for over a year during that time. Nothing related could have been disturbed during this time.
How do you troubleshoot this when all connections, etc. look OK? I would suspect reverse polarity, except nothing has been disturbed or changed. All suggestions welcome!!
MH

 

[6APPEAL]

Try to narrow the problem down before getting drastic. It's a PITA, but worth the effort. Have you tried swapping the passive crossovers left to right? If the problem moves, it probably a cap gone bad in the crossover. Time to buy new ones. Double check connections and settings (if any) while you're messing with them (both speakers and crossovers).

Not it? Try swapping the channels on the amp outputs (left to right first, then front to rear) to see if the problem moves? If so, it could be a channel related problem. If not, could be a bad speaker wire. Run a temp one outside the car to test.

Not fixed yet? If the problem moves with changes to the amp channels, it raises a few more questions. How is the head unit run to the amp? 2 channel or 4 channel input? High level or low level (RCA) input?

Remember the channel swapping, gotta try it on the input channels. It could help determine if it's the head unit or amp without having to go to the trouble of measuring the amp and/or head unit voltage. If the problem stays put when you move the input channels, it's most likely the amp. If the problem moves, it could be the head unit or a bad cable. Run a known good cable outside the car to test.

If you feel the need to measure the output voltage, take your volt meter and measure the voltage (music is A/C) at the speaker outputs. Probably best to use test tones also, music is variable. Compare side to side, the reading should be very close to the same. If different, check the input voltage to determine if it's the head unit dropping a channel.

Give it a shot and get back. Sorry so long.
John

 

[Powder]

Thank you for the advice and no need to apologize for providing useful information that can benefit many, I'm sure.
My crossovers are buried under the front seats which will have to come out to access them so, I think I will try to swap output channels at the amp first.
For some reason that I can't remember why, I only ran one lead from the head unit to all four channels at the amp, using a splitter. I know I lost fade or balance but for whatever reason didn't care at the time. My head unit has a separate output for the subwoofer which I connected the the other 2-channel amp. I don't see how using one lead for all four channels could cause this but I'm definately not a pro. BTW my four channel amp is a Planet Audio 75W X 4.
Thanks again.
MH

 

[6APPEAL]

Brand doesn't matter. Sub doesn't have the problem, so no worries there. 1 RCA lead makes it a little easier. Try taking the splitters off and plug directly into each set of channels the amp. Could be one of the RCA splitters gone bad. Just eliminate 1 area that could be the problem at a time. Also try to work from 1 end to the other (head unit to speaker or speaker back to head unit). Take you time, don't just jump in and change a bunch of stuff. 1 step/piece at a time and you will find the issue.
John

 

[Powder]

Brand doesn't matter. Sub doesn't have the problem, so no worries there. 1 RCA lead makes it a little easier. Try taking the splitters off and plug directly into each set of channels the amp. Could be one of the RCA splitters gone bad. Just eliminate 1 area that could be the problem at a time. Also try to work from 1 end to the other (head unit to speaker or speaker back to head unit). Take you time, don't just jump in and change a bunch of stuff. 1 step/piece at a time and you will find the issue.
John

I switched channels at the amp and nothing changed so I now know the problem is between the amp and the speaker. I have high confidence in my speaker wiring and connections so I'm betting the crossover is the culprit cosidering the car sat for over a year while building the new motor. The components and head unit have no more than two hours total usage on them at moderate volume levels so I would not have expected one of them to fail so soon. I hope to get back to this later this week so will post results when corrected.
Thanks again John, for your help.