Weird speaker problem on after market rad

I have a customer (Best Buy employee) who came in with his own speakers. He has a 2000 Hyundai Tiburon. We replaced all factory speakers with co-axle speakers. They were mismatched sets, but both good names, Rockford and some thing else. I put all speakers in and just played them quick at medium volume for just a minute, and they sounded great. He already had a Panasonic HU installed at this time. The next day the customer called and said when he would turn the system up ALL SPEAKERS would cut out, then back on, then back out, and then on… So then over the phone we figure that with the radio faded all the way to the rear the problem goes away. With it faded to the front they cut out. I checked the boxes and all speakers are 4 ohm. I’m lost at this point. He brought the car here because he “Didn’t trust his co-workers install” and now this. Any help, ideas, or similar experiences? Thanks

i might be wrong but it sounds like a short.if so that means it is shuting down the amp in the HU so no sound. it beening the doors might have happen when they shut the doors.

I did a full custom install on a MG once and had to cut holes in the rear for 5 ¼ speakers. When I got them in, no sound at all. Then I did some testing and found exactly that, one rear speaker was shorting out. Fixed it everything worked.

Well I thought of this immediately but sort of ruled it out because, the doors on this car have huge plastic speaker baskets, I mean huge. So that cant be the problem. Now as far as pinching a wire in the door, maybe. But why just after I put new speakers in? also its only once you hit a certain volume, not a bump or anything.

i did a 350 z the other day and it work perfect when it left the shop came back the next day said that it will play just fine until you truned it up to 25 on the radio and after 25 it would shut down his 4 channel amp. on a 350z i had to cut out the bose speaker to use a 11/2 inch spacer. i didnt think it was the problem to becuse of the 11/2 inchs of plastic. come to find out it was the termail thouching the door just alittle