Poor sound unless faded
 

Simple stereo set up, nothing special- head unit feeding 4 channel amp feeding front components via crossovers and rear 6x9's. Had the Blazer in the shop for some work requiring the body be lifted off the frame. Of coarse the interior had to come out to accomplish this, including my stereo amp. Driving home after picking it up, the stereo sounded awful. And I noticed a pop when turning it off that wasn't there before as well. I rewired it correctly when I got home but it still sounded weird, better but weird and pop still there. I wanted a more powerful amp anyway and from what I could tell from researching online, that was the most likely cause so I got a new amp. I wired it up this morning before the Texans thumped the Bears (sorry, had to plug my team) and still no change. I've verified the polarity on all the speakers, well just to the crossover for the fronts, (I don't THINK they would have taken crossovers out or even need to touch them) the amp, RCA cables are plugged into the correct ports, reset the head unit and everything I've checked is correct. And here's the thing, if I fade the sound to either the front or the rear, the audio quality goes way up! With the fader set to zero, feeding all speakers equally, vocals are barely there, no bass, and it seems as though there's an echo to the music. Any help would be much appreciated! Thank you

Re: Poor sound unless faded
 

If they had to take the body off the frame, the first thing I'd be looking at is GOOD grounds. I'm no expert but grounds are the cause of many gremlins!!

Re: Poor sound unless faded
 

Thanks for the reminder Ranger. I didn't think to look at the grounds underneath the truck. I'll check that as soon as I get home from work. I really hope that's it cause I can't think of anything else. Any and all thoughts on this are appreciated so if anyone else reading this has a suggestion, please let me know. Thank you.

Re: Poor sound unless faded
 

Question, would running a temp ground from the radio and the amp to the battery be a decent test to see if it is a poor or missing ground? Everything on my truck was working great until I got it back from the shop, so i really feel as though the issue was caused by something they did or didn't do. Also, I checked polarity on the crossovers and to the speakers they feed, they were all correct.

Re: Poor sound unless faded
 

I think I would try grounding it to the frame first.

Re: Poor sound unless faded
 

Cleaned up the grounding going from the amp to the chassis and verified continuity from the amp grounding lug to the negative post of the battery with my digital multimeter. I'm so frustrated! This makes no sense to me. Good sound when faded to the front, good sound when faded to the back. Terrible sound when all centered.... I just don't get it.

Re: Poor sound unless faded
 

Problem solved. There is a pico fuse on the stereo circuit board near the RCA outputs that will blow if the RCA cables are hot swapped. By hot swapped, I mean unplugged and plugged back in with the system turned on. Apparently Pioneer head units are prone to have this happen. The damn thing is very, VERY tiny. I un soldered it, took it off and just put a tiny blob of solder over it. Came across this kinda by accident. I was checking everything with a DVM and for the hell of it decided to check for DC on the RCA. When I applied the point of the probe to the RCA outer surface it slid down and made contact with the chassis and grounded the RCA When that happened....viola....nice sounding music!! I spent the next two hours reading up on how to fix till about midnight. Got home this afternoon, did the above repair and it's all working great!!