# Amp Shutting Off Due to Low Voltage?



## samdoan (Mar 17, 2009)

I have a fairly simple setup in my car:

Battery
4 Gauge
Distribution Block​10 Gauge​10 Gauge​Alpine MRP-F250 (100Wx2 RMS)​Alpine MRP-M350 (200W RMS)​Cadence CWM6-Kit​RF Punch P1 4ohms​
As of my recently, my subwoofer amp (MRP-M350) will turn off sometimes at random. Sometimes I can go a whole day with no problems, sometimes it will turn off while driving, and sometimes it turns off while stopped at a red light. However, my four channel MRP-F250 never turns off.

I've tried to recreate the problem but I can't do it consistently. The other day I had my car turned on, parked, headlights on, and playing music at a pretty decent volume and I had no problems at all. Later, I drove to the store and my amp turned off as I was at a red light.

I'm almost sure it's an issue regarding voltage. When the amp turns off, I power my headunit off and then on and the amp will start working again. However if the amp is getting low voltage, wouldn't my other amp shut off as well? Both amps are powered by the same 4 gauge wire coming from my battery and connected to the distribution block. I have never had my 4 channel amp shut off.

Could this be weather dependent? I'm not 100% sure but this problem might occur more often when it is raining than when it is dry.

I have measured my voltage with a DMM. At idle, I read about 14.2-14.5v and with my system playing at a decent level I get anywhere between 13.2-13.8v.

Any help would be great thanks!


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## HertzGuy (Jan 23, 2010)

Did you check your grounds?


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## samdoan (Mar 17, 2009)

Yeah both amps are grounded to the same point which is completely clean.


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## Oliver (Jun 25, 2007)

It's the alternator and battery , SISO , you need more power to run your system .

Some people can bench press a really heavy weight repeatedly .... but, there comes a time when they just can't do it ... not even once more.


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## samdoan (Mar 17, 2009)

Is my mono amp more sensitive to voltage drops than my four channel amp? It's just weird that my 4 channel keeps on going strong when my mono amp cuts out. And this could be at very moderate volume levels.

Maybe my battery has gotten tired? Before I had the four channel amp, I ran only the mono amp at 2 ohms pushing about 350w RMS on paper. This ran flawlessly. Now I'm running the four channel amp bridged and the mono amp at 4 ohms yielding about 400w RMS on paper. I don't see how this small increase in power would stress my system that much more especially considering I don't really listen to my music at ridiculous volume levels.


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## Oliver (Jun 25, 2007)

Connect the mono amps to the other speakers .... now, bridge the 4 channel to the subwoofer.

To make a tweeter work = 2 - 10 watts

To make a subwoofer work = ??


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## sqshoestring (Jun 19, 2007)

Put your DMM on the sub amp and try to make it quit, if voltage its a wiring problem to the amp or amps. One might shut down before the other hard to say, most amps play to about 10v but a sub amp can also spike the power down worse than non-sub amps. 4ga is good for over 1Kw rms. Also check the sub wiring, sub ohms, even hairs of wire on the terminals. Check any fuses and holders for corrosion/etc. Check the body to battery grounds under the hood.

If you can get it to stop and voltage is high, it is protecting because of the sub (low ohm load, shorted wires or VC) or heat, or internal issue.


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## tanakasan (Sep 8, 2007)

Could be the amp preparing to give up the ghost.

I had a Nine.2x that would play great for weeks then not play or play real quiet and scratchy. It would sometimes play and sometimes not come on at all. Every time you start the car, it was a crap shoot whether it would play. Eventually it just stopped playing, period.

Robert


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## samdoan (Mar 17, 2009)

I think it's very possible that the amp could be dying on me. I mean honestly a$$hole does have a point, however I don't think I'm really asking that much of my car's battery/alternator. I'm sure most would agree that I have an extremely modest system.

I would love for the problem being a dying amp. It would be an easy fix. The only thing is that this amp serves me well and I probably wouldn't replace it unless I had to. I guess what I need to do is borrow another amp and see if this problem still exists.


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## fast306stang (Jul 1, 2009)

Have you checked to see if the amp is shutting off entirely or is it going into protect? Could be a thermal issue...is the amp hot to the touch when it shuts off?


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## bikerider (Dec 28, 2008)

Also check the remote turn on wire for the sub amp? I know you checked the grounds and it doesn't sound like a lack of voltage. If that turn on-wire had a short in it or was loose it could cause the amp to shut off.


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## samdoan (Mar 17, 2009)

It's an alpine amp so I don't think there is a protect indicator. If it turns off and I go to my trunk the blue light on the amp is still lit meaning its still on which is weird. The amp does not get hot.

I have checked the remote. But again, when the amp stops working, the power light still remains on.


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## ChristianM (Jun 15, 2009)

What kind of distro do you have? i had a similair problem and it was due to the poor installation of my knu konceptz distro block xD if it was the remote wire, why would it cut off? would the map just be on all the time?? i though the remote wire was to let the amp know when to turn on, but then again i am a noob lol


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## tplaya07 (Mar 6, 2010)

You have 2 amps. Do you have 2 remote wires, or just one from the H/U and then daisy-chained to the other?

I know you mentioned you checked the connections at the amp, but have you checked the connections behind the H/U? *If* you are running two seperate remote wires (one to each amp), I would definately go ahead and re-crimp them just to be on the safe side. And while your back there, make sure that ALL unused wires are capped....just cutting them does NOT always do the trick. If unused wires are only cut/snipped, there is still a possibility that it can touch metal and short out. Oh, and check the RCA's for the amp as well, just to make sure they are not damaged/broken. I have seen people break their RCA's by pulling on the wire, rather than the head/connector to disconnect them from a device.

Also, the sub you have is definately a SVC 4 ohm, correct? (I don't know if you bought it new, used, etc.). I only ask because if it is actually a DVC 4 ohm, and your amp putting out ~350RMS at 2 ohms, the 10ga power/ground might be an issue. You could always go ahead and bump it up to some 8awg just to be on the safe side.


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