Question about Alpine MRV-F345 Car Audio Amplifier

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Have 2 amps, 1 for subs, other for speakers. The one for speakers just started shutting off

If I turn the volume up past half it shuts down and when I turn key off it resets and works till volume is raised again

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  • chandler21 Oct 11, 2007

    amps are not identical other is a kenwood and it works fine,as did the alpine until recently

  • chandler21 Oct 12, 2007

    4 speakers,boston acoustics in front, pioneers in rear. both 6x8 both coaxials. dont know about the v/c being in series or parallel. they connect to the amp by placing wire in to a hole and tightening a set screw, the power, ground and remote wires also connect that way




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This can be caused by too low of an ohm load, such as wiring subs in parallel at lower ohms than amp recommends. Or short speaker to body of car can cause it, or amp could have an internal problem. Like stated above try each speaker or disconnect one at a time to see if it is a speaker/wiring doing it. If amp gets too hot can also do it, but often it is overcurrent in the amp if it does it with high volume. Another less common issue could be lack of power so amp is drawing voltage too low for it to run, like if your fuse/wiring has a bad spot cutting down current or is not large enough/corroded/bad ground/etc.

Posted on Apr 22, 2008

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Are the amplifiers identical?


Do both amps shut off?

Posted on Oct 11, 2007

  • Perry Babin Oct 11, 2007

    The MRV-F345 is a 4 channel amp. How do you have the speaker(s) connected to it?


    How many speakers?


    Number of voice coils per speaker?


    Rated impedance per voice coil?


    If DVC, are the coils wired in series or parallel?

  • Perry Babin Oct 12, 2007

    Disconnect all of the speakers and turn up the volume to the point where it would normally shut off. If it doesn't shut off, reconnect one speaker at a time to see if any single speaker makes it shut off. If the first speaker causes the amp to shut down, try a different speaker on that channel. If you find that one speaker causes the amp to shut down, inspect the wiring for that speaker.





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Try a different set of speakers or if it keeps going into protection you have a channel going bad.

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I have a kenwood kac-9152d amplifer and it works just fine for about 10 minutes then just shuts off and subs dont work, about 30 seconds later my amp turns back on with the subs.

make sure it's well ventilated. If there's no air flow, then there is no way of cooling down and to protect itself it will shut off. Make sure the speakers are wired correctly as per amp specs. too many subs or subs connected improperly can draw too much current and shut the amp off, but you will notice this when you turn up the volume to a certain point and the amp shuts down.

Aug 30, 2011 | Kenwood KAC-9152D Car Audio Amplifier

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Well i was driving one day and my subs just whent out so i bought brand new wires and hooked everything up but the power protector light turns red whenever uu turn it up past volume 10 i really do not know...

It sounds like your amp is going into protection. I know it's frustrating, but this is actually a good thing. If you subs you have are drawing too much power and the amp can't keep up, it will shut off instead of melting the board. Usually, the protection mode only last a few seconds. The user normally turns the music down that the protection shuts off and the music plays again. I recommend looking at a larger amp for your subs, if you are going to play them that hard.

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My alpine keeps shutting down when the volume is turned up past 20. Plus I have no sound coming out of my subs. I tried switching rca cables. And I sent my amp off thinking it was my amp. Their is a little...

so it turns off suddenly and then the next second it turns back on and starts playing

from that and personal expericance i belive that the radio system (radio and amp) is not reciving enough power

is this radio inside a car
if so what car

what i would do is attach bigger thicker wires to the positive and negative of the amplifier
direct from battery

positive of battery>>>> positive of amp
metal grounding point on car>>>>>> negative of amp
(do not use negative of battery use the metal of the car)

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I have the pioneer sub and a sony 600watt 4

it has a detector that kicks in it will usually shut off your amp and it keeps you from blowing your amp the speaker may have to much power and amp may not push it it will start to protect itself

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Amp Turns of when i put the volume up to 20

if it only happens when you turn it up, you could be sending it too hot of a signal and its clipping so the amp is protecting it self and shutting off. Try lowering the input gain on the amp and see if that helps. It's also possible that your speakers are pulling to much power when you have it turned up that high and the amp is shutting down to keep from overheating. I don't know what or how many speakers you have hooked up, but if you have a sub, try it without that and see if you have the same problem. If you don't have a sub, disconnect the largest woofers you have. Different speakers have different ratings for how efficient they are. It's usually measured by how much SPL 1W will produce. You want to disconnect the speakers that are pulling the most power and try it again. If your speaker is pulling more power than your amp can supply, your amp could shut off because of that. As well as cook the voice coils in the speaker and damage the amp. It's always better to have too much power in your amp than not enough. There's an old joke I learned in audio engineering school "I can pass a square wave.....once."

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Sound shuts off, sub still works

That is a common problem with this radio, for it can not go to loud without going down in volume or shutting down.

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1 Answer

At high volume sound shuts off, subs still work

You most likely have a shorted or damaged speaker, which is causing the internal amp chip to shut down (but does not affect the preamp outputs). A test you can do is to fade to one speaker at a time and turn it up to se if it shuts down. Repeat with each speaker until you find the one that causes the fault. Then replace it.

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