Brand new sub and amp but no sound from Sub??


Standard Member
Hey errrone.

Sorry to come on and just ask a noob question here. I just need some advice from some smart people on this subject.

Well I have an e36 BMW M3 and about six months ago put a new headunit in for my stereo. An alpine cda-105. It works great. Then this week I got my new setup for my subwoofer system. I got an Alpine mrp-m500 amplifier, and a Rockford Fosgate P3D412. I kinda liked the idea of this setup. So if you wish to comment on this combination, please do, but the help that I need is a little different.

Yesterday I wired everything. I did HU to amp, rca and remote. Battery to amp(4gage) and amp to ground. And then amp to sub. I plugged in everything to make sure it all worked before i started mounted stuff and guess what... no sound!! The amp is definitely getting power though. It's blue light turns on.

I have checked the easy answers like change your subwoofer output settings on your head unit and I unmounted my sub from the box to see if something was wrong with the speaker wiring. Nothing was wrong. So my guesses right now is that the rca is bad, or the amp is bad somehow and it isn't puting the sound out to the sub. Today I am going to test everything with a different amp and maybe a different sub if I can find one.

So what should I do? what could be wrong? This is my first time wiring my own system but I am a Mechanical Engineer and understand this stuff pretty well(haha not electrical stuff as well though). So if any of you experienced people have an idea, please help me!


Distinguished Member
This forum is for home AV subwoofers. You really need to find a car ICE forum for this issue.
Have you checked the crossover setting on the Alpine amp and also the gain level?

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