Alpine MRV-F250 crackling - worked fine yesterday.


New member
Username: Tcmarley

Post Number: 1
Registered: Dec-05
Hello, I am in the process of setting up a 1998 M3 convertible stereo system and have a problem that I can't seem to solve. Any suggestions would be appreciated.

The M3 comes with a piece of garbage Harmon Kardon system that runs 10 speakers off of a single HK amp all running at 3 ohms. After trying to find some replacement parts I decided to replace everything in the system except for the head unit. I now have Infinity 6.5 Coax in the front, Infinity 3.5 coax in the doors, Infinity 5.25 coax in the back and a single JL Audio sub in a custom box in the rear.

I purchased two amps - a Alpine MRV-F400 four channel amp for the 6.5's and sub (bridged) and a Alpine MRV-F250 for the 3.5's and 5.25's. I cut the factory wiring harness and routed all speaker wire from the head unit to a 4-way line output adaptor to get RCA's for the front and rear. I tested each amp and everything worked fine before I put it in. After wiring the F250 up and testing the 4 speakers everything was sounding great. I hooked up the 6.5's and sub to the F400 and turned everything on but the F250 now produces no sound. If I turn the volume way up I get a crackling/popping noise from the speakers but still nothing.

I am running the power and ground to the factory power and ground that used to run to the stock HK sub. Both amps get power, the line output adaptor is sending signals to both front and rear channels (which are split with a Y RCA to the inputs on the amps), I've tested the amp to speaker connections for all four of the speakers wired to the F250 and I get sound. The F250 worked and sounded great before I hooked up the F400.

My question is because I am splicing the power, ground and remote turn on to each of the amps could that be causing a no sound problem. I unhooked power, ground, remote power from the F400 completely and still get no sound from the F250 (with the wires still spliced together). I do have a power light that comes on for the F250 amp. I keep on thinking this is a sound issue and not power and there really isn't anything that changed on the amp from the time it worked to the time it didn't except that I spliced in a second power, ground, and remote power for the F400. The crackling noise suggests bad grounds on the speakers but I get nothing at all from all four speakers at low volume until I turn it way up and then just crackling and popping. All gains are at normal and filters that were set at high pass (when it was working), have been tested at high pass and off (full range) and still no sound.

This is giving me fits... the amp has power and everything sounded great but now even though the amp still has power I get no sound from any of the four speakers. The same RCA's that feed the front and rear channels are going to the F400 and they produce great sound. I am running the pre-amp non fading outputs from the F250 to the F400 for the rear channel (sub - bridged) and the sub works fine so I know the F250 is getting a signal.

Sorry for the long post... but I am stuck. I don't think the amp is blown.. it just worked fine 2 days ago. I am about go out and buy a meter to check everything, but any help would be appreciated.


New member
Username: Tcmarley

Post Number: 2
Registered: Dec-05
Disregard my post... I found the problem. It appears from having the trunk and doors open for 3 - 4 days (about 15 hours total) while I installed this system it ran the battery down to the point where it wasn't even producing 12 volts. It had enough to turn over the starter, but not enough to run the stereo system at proper voltage. After an 8 hour stint on the battery charger I think that I am OK because both amps work now and I get full sound from all speakers and sub.

It was a power problem after all.
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