I have a ~year old Alpine 9887 installed in my '94 Oldsmobile Cutlass Supreme. Basically, my issue is that I have some sort of interference/noise in my left rear channel. No matter what I've tried, it's always been in that channel.
What I've done:
Tried a new head unit: new head unit did fine and powered all channels perfectly. (Sony unit)
Tried new speaker wiring to both front and rear speakers: no change.
Tried different speakers on that channel.
Tried directly connecting speakers to stereo's wire harness: no change.
Made sure all positives and negatives were correct: no change.
Went from stock Cutlass 6 speaker setup to new 14 awg wires running to just door and rear speakers: no change.
Sent head unit to United Radio to verify stereo was ok: they verified everything working correctly.
What I haven't done:
Tried a new wire harness to the Alpine unit: need to find one on eBay..
So, if anyone has any other ideas, it would be greatly appreciated! I cannot for the life of me figure out what the issue is. I always, ALWAYS, get muffled sound in the left rear channel, no matter my configuration. My deck is currently set to Fr/Rear/Sub as far Xover goes.
If you need any more information, I'm happy to supply. I've been trying to figure this out for over a year now! Please help!
EDIT: My front speakers are 4ohm 4x6 Infinity's and my rear are 6x9 2ohm Infinity's.