Question about Alpine MRP-M450 Car Audio Amplifier

2 Answers

Alpine amplifiers fade in and out durring high volume bass hits

I bought 2 alpine mrp-m450 monoblock amplifiers brand new less than 6 months ago. they had been working fine for quite some time, then i noticed one day that the bass coming from them had decreased noticeably and at almost full volume you could hear a steady note ( or one that was supposed to be steady) get louder and quieter during the note. you could also see the subs (2 kicker cvrs, one per amp. each amp at 2 ohms) kind of fading in and out. they would move to the correct excursion, then during the supposed to be constant note, loose power and not move as far, and so forth. i took out the amplifiers and noticed there was condensation on the outside of the amp. i let them sit in my room for a week to dry out, put them back in, they worked like new. may have been a coincidence i dont know. well they are doing it again and there is no condensation on them or in them. any ideas as to the problem? my grounds and pos wire connections are fine. speaker connections are fine. i dont know what the problem could be. thanks
-peter

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  • 6 more comments 
  • TDWPgtp Jan 06, 2009

    i have 4 gauge running from the battery to a distribution block, then from there i have 8 gauge (manufacturer recommended) to each amp. i do have a 245watt rms 2 channel of the distribution block too. do u think that this is too much power to be drawn through 4 gague? another thing is the amps recomend 40 amp fuses in the inline (dist block) but i was only using 30s... i didnt think it would matter since i never have the gain all the way up.. might that be it? and yes the power is fused directly off the battery.

    thanks

  • TDWPgtp Jan 09, 2009

    ya i think i messed up when i posed before. alpine recomends 2 20 amp fuses in the amp, which i have in there. but i have a distribution block splitting the 4 gauge into 8 gauge. alpine recommends 8 gauge so thats all good. in the dist. block i have a 30 amp fuse for each 8 gauge wire. i will put in 40s since that is what alpine recommends for the inline fuse. im pretty sure the wiring is american bass. ill check to make sure and ill check how many strands. as far as the alternator goes, i know i need a new one because my lights dim tremendously. i have done the big 3 wire upgrades with 4 gauge, and the ground on my amps is attached via bolt and nut to the sheet metal inside the trunk. it has been sanded down to the metal. all power connections are good.



    ps thanks for being persistant with the posts and not givin up on me ha

  • TDWPgtp Jan 09, 2009

    i used a crimp on ring terminal for the 4 gauge ground. its a pretty good looking crimp. almost all the wire is spread out enough to touch the ring terminal. i just put in a 900 watt rms kenwood monoblock (CEA certified, true power) instead of the alpines to see if it continues to do this. so far so good but ill drive around a bit to see. maybe its just the alpines amps... the kenwood is being run at 1 ohm but IS 1 ohm stable. we will see how things go..

  • Wayne Bayley May 11, 2010

    Hi Peter. Are your woofers boxed in a common enclosure or in seperate enclosures? If seperate enclosures, disconnect 1 amplifier so that you are running single woofer single amp only and tell me what it does.

  • Jimmy Hall
    Jimmy Hall May 11, 2010

    theevilomeno: i'm glad you had access to another amp. because we were down to either the way the speakers were connected to the sub-amps or the amps themselves. i also like the fact that you know the difference between the inflated output power ratings & true RMS rated power. too many buyers get ripped-off by bogus ratings.
    going back to something you said in your 1st (i think) post, saying that you found moisture on the inside of the alpines. the better mfg's seal their boards, so it shouldn't have been a problem. all the same, if possible, mount the new amp up off the floor to avoid any potential problems. make sure the trunk/hatch area seals are good & that there are no holes in the wheelwells.

    peace-out

  • Jimmy Hall
    Jimmy Hall May 11, 2010

    theevilomeno: it sound like the grounds were properly executed. you did not mention how the wire terminals for the power & ground wires are attached. if those are not properly crimped or soldered that can cause intermittent operation. let me know & well' slugging away on this.

    peace-out

  • Jimmy Hall
    Jimmy Hall May 11, 2010







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    i'm going
    to scream. not your fault. i just spent considerable time posting a response
    only to have fix-ya's page lock-up & lose everything. i've tried twice since then & gave up last night, so we'll try again.






    anyway
    the short of it. double check that the wiring, ground connections, wire
    terminals, etc are solid. alpine recommends you use 2 each 20A fuses per amp
    & i say you follow their instructions. spreading current sources over
    multiple devices lowers the chance for heat build-up, which can lead to
    resistance problems. the fact that you used single fuse holders/blocks per amp
    may have created a problem.






    the 3rd
    amp doesn't appear to be a problem. with all three amps running @ max output
    you may be drawing 60-70A.






    tell me
    how the wire terminals & grounds were completed.






    4awg wire
    is rated @ 135A & 8awg @ 73A. so the wire isn't an issue. what kind of wire
    are you using? how many strands. current travels on the surface of a conductor,
    so more surface equals higher conductivity. that's why you will see braided or
    flat ribbon wire used for speakers in high-end systems.






    lastly,
    there's a possibility that your alternator is underrated. you may have to
    upgrade to a higher current alternator &/or add a second battery. if you're
    drawing 30-50A with the sound system along with running everything in the car,
    it could be too much.

    after you have checked everything, get back to me.

    peace-out


  • Jimmy Hall
    Jimmy Hall May 11, 2010

    what wire gauge are you using? what does the mfg recommend? are you supplying the amps with separate power wires. the reason why i'm asking is if you used wire that is undersized, @ high amperage usage it will start to breakdown & the resistance will increase. when the resistance increases it will limit the amount of amperage available to the amp which causes the amp to "clip" the audio @ high audio levels. you see the voltage doesn't change when you turn-up the volume, but to create all that sound you need lots of current or amperage.

    Also make sure the power wires are fused directly off of the battery. respond & willgo from there.

    peace-out

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  • 47 Answers

Main problem i think you are having is your loosing power when it kicks a note.. get a power cap! power caps feed your amps constant power! this will solve your problem :)

Posted on Apr 20, 2009

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  • Contributor
  • 8 Answers

Moisture probable settled in the amps and now the boards are acting up try getting new amps and see if that helps i would recommend getting a 2 sub box with a shared port hole and run it off a bigger amp 1000 watt max that way u can have alot more bass

Posted on Jul 25, 2010

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  • 149 Answers

SOURCE: subs dont work when base is up high

Sounds like the amps needing more current available to it-You should have 4 gauge power coming off the battery going into a distribution block from there a 4 gauge to a 1 farad capacitor off the block -4 gauge to the ground for the capacitor -and two + leads from the block to your amps-you would do well with 6 gauge there.- That is to ensure that you have plenty of power on tap when needed and not trying to draw it off your charging system on heavy current demands.Make sure that your grounds are well placed and solidly connected. As for putting 600+watts on a pair of 8z......i hope that they are the CVR or the L5 / L7 series to take that much power,I've seen it done and the ones i heard sounded badass(L7 series)-but that was at the stereo shop so they had they stuff on HITTN status up in there. If your running the "cvr" or the "comp" series you might be throwing too much power on them -might want to step up your subs to a set of 12s just to get more air moving in there- good luck

Posted on May 28, 2009

  • 133 Answers

SOURCE: Alpine mrp-m450 Amp won't stay on

Sounds to me like it might be the remote turn on because the first time i installed it, it did the same thing, and i found out that there is two blue wires coming out the stereo, one with a white stripe, i connected it to the blue wire, and it didnt work, then i connected it to the blue and white wire, and it worked. Well hope this solves your problem, goodluck.

Posted on Jul 06, 2009

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