Question about Alpine MRP-M650 Car Audio Amplifier

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Amp staying on but cutting out?

Alright it's getting real old, and expensive! At first I thought it was probably my amp but bought another amp and I am having the same problem! The power to the amp is staying on but My sub just stops hitting,and it cuts in and out, It will work for as long as I'm driving I will park my car, and when I turn it back on every thing will be working just fine and, then a couple minutes later, amp cuts out and won't hit for a couple hours or a couple days.... I have checked the sub multiple times and I don't see it being the sub or the amp... I have never had this problem before, and I had been running the same sub and amp for a year and a half, and never had a problem till now(and now I have tried 4 different amps and still the same thing happens).... so my guesses are it's grounding somewhere, short in some of the wiring, might just need a new battery...Idk could use some help on this one! Thanks

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  • Willb2396 Nov 13, 2008

    Thanks for the help, but I had a buddy of mine who owns an audio store look over everything, and It turned out to be nothing but the wiring in the box, It wasn't a problem with the alternator or anything of that nature, just turned out to be something I overlooked, and didn't think to check, which was a screw up on my part! Just goes to show it always turns out to be something simple, which really sucks cause I did strip everything down to make sure nothing was grounding out! And the only reason I did mark as "Thanks for Trying" is because I was pretty sure the alternator wasn't going bad because, the car is pretty much new with only 15000 miles on it, and I am only running around a 600 rms amp.. But thank you very much for the help, I do appreciate it!


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It's cool man! We all have those days! once again thanks for the help

Posted on Nov 14, 2008

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Hello Willb2396,

Actually you answered your own question in your paragraph. I draw your attention to your statement of:
"It will work for as long as I'm driving I will park my car, and when I turn it back on every thing will be working just fine and, then a couple minutes later, amp cuts out and won't hit for a couple hours or a couple days.... I have checked the sub multiple times and I don't see it being the sub or the amp"

You are correct it is neither the Sub nor the Amp. The problem is either your voltage regulator or your alternator. one and or the other is going bad.

Here is some advice check your ground wires, the buy a dual alternator kit, it contains the parts you will need to add an additional alternator to your car. This will provide the power you need.

I hope this helps,

Thank you,


Posted on Nov 10, 2008

  • Henry McKelvey
    Henry McKelvey Nov 13, 2008

    Hello Willb2396

    I have a question, "what do you think the problem is?" Because by your own admission you have tried a number of Amps and Subs, so we know that it's not the subs and amps. You believe its a grounding issue, OK in that case recheck your ground using an ohmmeter and making sure you have no ground loops. Now after taking care of that there is only one system that applies here and that is the vehicle's power plant (Battery, Alternator, and voltage regulator which is sometimes part of the Alternator). Correct me if I am wrong, you have eliminated the Amps and the Subs as problems, you have checked the grounding to make sure it is secure and ample? Now in that case what is so out of line with my advice that it warrants a ":Thanks for Trying" since it is the only system left?
    I understand that this is a lot of work and you may not feel like adding the extra alternator and voltage regulator, but, that is what you need because when you stop driving the car goes to idle, and the output of the alternator at this point is not enough to support the power needs of your sound system. So in order to take care of that, guys who do this for a living, such as a few people I know including myself do is add an extra alternator and beef up the grounding plane. What I did was to employ what is called a ground window, which I run all of my grounds to and then run a single heavy gauge ground cable to the automobile ground.

    The problem you are having is a power plant issue which may be exacerbated by the lack of a good ground plane.

    In any event, I wish you well in finding the solution to your problem.

    Thank you,


  • Henry McKelvey
    Henry McKelvey Nov 13, 2008

    Hello Willb2396,

    First I would like to apologize for my attitude, I had a bad day, but that was no excuse to vent on you, I was working on a system and found that someone had completely redone what it took me two weeks to do and I was in one of those moods that get folks into trouble. So as stated before I apologize for my venting on you.

    I am glad to hear that it turned out to be as simple as a wiring issue. Again I ask that you accept my humble apology for without warrent venting at you.

    Thank you,



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