Sorry for the long ass post...

So on friday i decided to get a 4 channel amp for my speakers, i got the Alpine MRP-F250. I already have a JBL BP600.1 for my sub, it delivers 600W RMS to the sub. The new alpine amp delivers 40W RMS to each speaker so 160W total. For power, I had an 8 gauge power/ground wire for the JBL amp.

I forgot to get a power kit and wanted to install the amp friday night, so using extra wire (8gauge) I had around, I just split the existing 8 gauge wire to both amps and split the ground wire for both too. So when I was done, it was time to test it out, and the problems begin.

When I put the volume past 12 on most songs, the amp would cut out, it wouldnt shut off completely. If i turned the volume down a little it came back on. However, no matter how high I put the volume the sub amp wouldnt cut out, although I've never had a problem with it. I checked and double checked EVERY connection I made or modified during the installation, everything was good, problem still there.

So saturday I got more 8 gauge wire, I decided to run a seperate power wire for each amp. I also replaced the positive battery terminal, positive wire ring terminals, and ground wire ring terminals. Each amp now has its own 8 gauge power wire and ground wire. I also sanded the grounding point a little more, and replaced the self tapping screw with a nut and bolt for a tighter connection. Time to test it... turn the volume up to 12, doesnt cut off! Then 13, 14, 15... and it cuts off WTF??

So I turned off the sub from the head unit, didnt help, disconnected the remote turn on to the sub amp so it would be off completely, didnt help. Sanded a new grounding point for the alpine amp with a nut and bolt, didnt help.

Ive had the sub amp (600W) with an 8 gauge power wire in there since a week after I got the car, and I've never had any problems with it cutting off, and the new amp is 40W x 4 so its certainly not too much for the car to handle. As far as I know the battery and alternator are fine and operate as they should.

One other thing, when the engine is off, there is no output from the alpine amp no matter what the volume is, even though the amp is on. However the sub amp works fine.

I'm truly stumped, any ideas would help, thanks!

 

check ground.