Sub randomly cuts out

[colt22]

I have an Alpine MRP350 4 channel for my speakers and a MRP500 Mono amp for my 12" MBquart sub. When I turn the volume up on my headunit the sub and only the sub will cut out.. or if I have been driving for more than 5 minutes its sure to cut out at any given point in time. THe light remains bright on my MRP500.

The issue is remedied by restarting the headunit.. which makes no sense to me. I have checked the wiring and ground and its all good, it was done professionally.

Anyone know what the issue may be?

Thanks

[1slw4dr]

SUN???? how?

[Cos]

OOOHHH GOD! MAY 21 IS COMING! The solar end is near!




















In other news.... overheating amp or headunit? Can you flick the remote wire on/off and get it to start back up?

[kaput]

.

[J-hop]

"don't let the sun go down on me"

yea I agree with cos, how ventilated is your amp, my buddy mounted his under a seat in his SUV and had to run cooling fans to keep it from overheating, used to cut out all the time prior to that.

also who did the install?

[03ozwhip]

i will say this. it is definitely an alpine amp thing. ive had 2 of those amps in 2 different cars with 2 very well ventilated areas and ive always had teh same issue. could never get an answer out of anyone.

the only thing i was thinking it could be is an internal breaker when the amp is getting too hot, it shuts down. ive never been able to find this info on these amps though to back it up. if you do, id like to know.

[colt22]

I considered overheating but the amp is cool to touch after it cuts out.. Must be an alpine thing.

[03ozwhip]

ya man like i said ive had probably 4 of the alpine mrp m series, 2 of the 500s and 2 350s. its something to do with the mono amps, i never had any issues with the other amps with components. again though, i havent found anything to back my theory up on it.

[colt22]

interesting, I suppose the amp must be inherently faulty.

Do you recommend any other Mono amps that work well?

[03ozwhip]

there are plenty. i really do swear by alpine but for some reason that 500 does that, dont know about the other higher alpines. JL audio is another quality amp id comare to alpine, havent heard that issue on those amps..

[J-hop]

Originally posted by colt22
interesting, I suppose the amp must be inherently faulty.

Do you recommend any other Mono amps that work well?

as I asked before, who installed it? ensure that your sub is wired for the correct impedance before junking the amp.

[colt22]

Visions SW location.. I find it odd that a simple restart of the headunit allows to amp to run again until it cuts out after an average of 10-30 seconds.

[03ozwhip]

^^^its not that man, trust me ive been dealing with different combinations of subs and amps for 15 years and this one paired with any other sub ive tried does the same thing.

ive used kicker L5s, L7s, infiniti, pioneer and mtx on this particular amp and it always does the same thing. nothing high end or anything, it just does it and like i said ive never been able to get an answer about it from anyone.

[TE4MFaint]

Amp is going into protection if you can turn the deck off then back on then it works again for whatever period of time.

Thing to do. Check your OHM load on your sub. MRPM's are very picky with ohm loads. If they see anything less than 1.8 ohms, it will go into protection mode very quickly.
If you ohm load is 1.8 or above, then your sub is fine. If its wired lower than this, its either wired improperly (if its a dual voice coil sub) or the sub is blown.

Check your settings on your amp. Hz should be around the 85-100 range. Check what your gain is at. Back it off a little bit if its over .5V on the amp. Put it closer to nom. And of course check the boost. Back off the settings, if this fixes the problem, then you're laughing.

Few quick things you can do, let me know how it goes.

[tictactoe2004]

I've seen more than one system with the exact same symptoms where the amp was clipping and caused damage to the voice coil of the subwoofer.

[colt22]

Originally posted by TE4MFaint
Amp is going into protection if you can turn the deck off then back on then it works again for whatever period of time.

Thing to do. Check your OHM load on your sub. MRPM's are very picky with ohm loads. If they see anything less than 1.8 ohms, it will go into protection mode very quickly.
If you ohm load is 1.8 or above, then your sub is fine. If its wired lower than this, its either wired improperly (if its a dual voice coil sub) or the sub is blown.

Check your settings on your amp. Hz should be around the 85-100 range. Check what your gain is at. Back it off a little bit if its over .5V on the amp. Put it closer to nom. And of course check the boost. Back off the settings, if this fixes the problem, then you're laughing.

Few quick things you can do, let me know how it goes.

Thanks for the suggestions, makes sense- I know I effed around with the HZ and HPF, perhaps this is the cause? Ill check in after changing the settings..

How can I check the OHM load?

[J-hop]

Originally posted by colt22


Thanks for the suggestions, makes sense- I know I effed around with the HZ and HPF, perhaps this is the cause? Ill check in after changing the settings..

How can I check the OHM load?

i believe the HPF is just a high pass filter, ie: low frequencies (i'd say about 25Hz and below) are essentially useless for most setups. So the HPF does exactly that, passes frequencies above the cutoff to the sub and attenuates the lower frequencies so they don't get passed to your sub.

the HZ function I believe is just to tune the dominant frequency to match your setup (ie: boxes will have a specific tuning frequency that you want to match your amps dominant output to)<- I think at least, I could be wrong but this makes the most sense to me.

I've forgotten most of my circuits stuff but I think you could just connect an ohm meter between the positive and negative terminals on the back of your box (do this with the amp off and disconnected from the box- ensuring you cap off the two wires so you don't fry your amp if you forget to turn it off prior), don't quote me on that or try it before hearing back from someone more knowledgeable than myself but I think this is how you would take a measurement. The problem with this method would be that it is a static measurement which speakers are not so you could actually be hitting lower impedance than what you measure.

You could also pull the sub out and see how it has been wired, certain wiring configurations produce certain impedance (wiring diagrams will be in your sub manual). I personally always wire my subs at a 4ohm impedance, yes it is conservative but I've never blown a sub and find I get a lot better sound quality.

[colt22]

So I kept forcing the sub to play by restarting my headunit and found to my horror smoke billowing out from the MB Quart sub- using simple deductive reasoning, its safe to assume the problem must of resided within my subwoofer, correct? however I have no idea what could of caused the issue.. overdriven perhaps? Doesnt make sense as the amp is only 500W and MBQuart is supposed to be a decent model. I didnt even know subs and amps could be 'mismatched.

Perhaps your sub could be the issue, 03ozwhip

[03ozwhip]

nah i went through too many subs, that would be to much of a coincidence fo at least 5 different subs connected to the same type of amp, its gotta be the amp.

[J-hop]

Originally posted by colt22
So I kept forcing the sub to play by restarting my headunit and found to my horror smoke billowing out from the MB Quart sub- using simple deductive reasoning, its safe to assume the problem must of resided within my subwoofer, correct? however I have no idea what could of caused the issue.. overdriven perhaps? Doesnt make sense as the amp is only 500W and MBQuart is supposed to be a decent model. I didnt even know subs and amps could be 'mismatched.

Perhaps your sub could be the issue, 03ozwhip

yea if a sub can only handle say 200rms and you pump 500rms through it you'd blow it in a second, but chances are if a shop installed your sub/amp it isn't mismatched (any reputable shop would have told you and warned you against it before installing).

Oz is probably right