[eaglescout]

I have a decent aftermarket setup in my car, albeit a few years old.
-Factory head with factory CD changer
-Alpine MRP-F320, 75W x 4 + 180W x 1 Amp
-Sony 12" Sub
-5" Pioneers Full ranges in doors (were 4" Rockford-Fosgate Mid ranges and changed after probelm started)
-Rockford-Fosgate tweeters (feed through a filter from the front speaker wires)
-6"x9" Kenwood Full ranges in deck

Recently, the speakers have started to cut in and out. It seems to be all speakers can cut in or out and they can do it independent of each other (the LF speaker may cut cut, then a little later the RR may cut out and then sometime later the LF may kick back in). They can all be working at the same time or they can all kick out (and when they are all kicked out I can still hear the sound, but very faintly).
Bumps in the roads and taking turns seem to be a catalyst for most episodes, but they can occur when I'm just sitting still.
The tweeters seem to be in sync with the corresponding front speaker.
I can't tell what the sub is doing, but it does seem when all the speakers are cut out I can't hear any bass coming from it.
I have had the amp thermal cutoff activate before after driving longer than an hour on hot summer days.
I have a sneaking suspicion it is the amp, but I'm not sure how to diagnose that. Anyone have any ideas/suggestions for the direction I should take?

 

[neuspeedescort]

check your ground
check your high-low convertor


NEUMAN

 

[eaglescout]

No High-low converter, it's straight speaker level output/input. Ground is tight, still screwed to the adjacent sanded fender wall as it always has been.

 

[Dave94LX]

it could be the factory amplifier in the stock radio that is intermittent. That would explain why it cuts in and out. Pay attention when the speaker goes out that you tapped into for the high level inputs to the amp. When that speaker goes out, the sub should also go out.

 

[eaglescout]

I didn't tap into any one speaker. The car came with a factory amp under the seat. I intercepted the speaker wires under the seat to go back to the Alpine. I'm not sure how it gets the amp generates the bass signal to go out to the sub.