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Old 05-09-2010
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Need help with amp diagnosis

Ok so I used to have 2 amps in my truck. one to each sub. i ended up selling on cause i wanted to upgrade but the buyer of the second one pulled out. so today after a few weeks of riding around with one sub going i decided to hook up my other sub to the amp i had. I have 2 Alpine Type R 12s running at 2 ohms each hooked to a Alpine M850.

My question is. since hooked it up if i turn my radio past about 25-28 the amp will cut off and ill have to turn it off and turn it back on with the volume turned down.

Does anyone have any suggestions on what this might be? or is it my amp doesnt have enough juice to push both of them to there potential?


Amp specs of the top of my head:

1 channel
500w [email protected]
850w [email protected]
1500w peak

subs specs off the top of my head:

Dual Voice Coil
1500w peak
500w rms
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Old 05-09-2010
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im not completely sure, but i do know some amps have a "safety auto off" ....none of the settings changed in the process of moving the amp? maybe turned up the gains too much? and it shuts off?
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Old 05-09-2010
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nope nothing changed. just hooked the wired up to it and this happened. ill try to turn the gain down i guess
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Old 05-09-2010
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my friend had a very similar problem like this. he just got some new RCAs and problem solved.

and how are u setting your gains? DMM? O-Scope?
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Old 05-09-2010
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i have no idea lol. i think the gain is a little pass half way. everything i was working fine this morning before i hooked extra sub up.

heres the amp

Alpine MRP-M850 Mono subwoofer amplifier 800 watts RMS x 1 at 2 ohms at Crutchfield.com
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Old 05-09-2010
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do u have a DMM?
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Old 05-09-2010
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what coils fo u have? how are they wired to the amp.
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Old 05-09-2010
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im guessing that is a digital muliti meter? i dont but i know someone who will being willing to let me borrow it
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Old 05-09-2010
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i believe they are wired as a parallel.

would it at all help if i wired them like this?
http://a248.e.akamai.net/pix.crutchf...4-ohm_mono.jpg
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Old 05-09-2010
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Quote:
Originally Posted by Willzane View Post
im guessing that is a digital muliti meter? i dont but i know someone who will being willing to let me borrow it
correct. set it on ACV and put it to your speaker outs on the amp. to find the proper voltage, RMS X ohms = B square root of B = C "C" is your voltage.

1) turn down gains, bass boost.
2) turn on song and increase volume until you hear distortion (back it down a little) from your speakers (not subs)
3) play a 50hz tone at ^^^^^^^ volume
4) set amp to proper voltage. if you use "bass boost" then u want to adjust that along with the gain. bass boost will change your voltage.
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Old 05-09-2010
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Sounds to me like you've got the amp wired at a 1 ohm load which it isn't stable at.
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Old 05-09-2010
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This is what ive got it like. i had it set up to run one to each amp and i just took the wires from the sub and added it to the other amp.
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Need help with amp diagnosis-setup.jpg  
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Old 05-09-2010
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Quote:
Originally Posted by korey89 View Post
Sounds to me like you've got the amp wired at a 1 ohm load which it isn't stable at.
thats what im thinking
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Old 05-09-2010
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at 4 ohms u are only getting 500 rms so 250 each.

i would get a 800-1200rms @ 1 ohm amp
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Old 05-09-2010
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Quote:
Originally Posted by the Answer View Post
at 4 ohms u are only getting 500 rms so 250 each.

i would get a 800-1200rms @ 1 ohm amp
any sugestions?
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Old 05-09-2010
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price range?
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Old 05-09-2010
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300 max?
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Old 05-09-2010
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NEW - US Amps Xterminator XT2000D - eBay (item 170480578085 end time May-31-10 21:57:18 PDT)

this will be good.
maybe look at a sundown, better quality than us amps but it cost more but its way worth it
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Old 05-09-2010
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Old 05-09-2010
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stay away from poweracoustik, its unclean power
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Old 05-09-2010
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so should i unhook the extra sub until i can get a 1ohm stable amp?
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Old 05-09-2010
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yeah
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Old 05-09-2010
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alright man, cool. thanks for the help. ill work up to getting that amp.
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