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    class AB amp bad choice for subs?

    ive got an MA-audio HK 1398 700w rms x 2 @ 1 ohm powering 2-12" MA audio XL's 600w rms/1200w max. XLs have 2 ohm DVC and obviously are wired parallel. the amp works fine for most of my music (rock and metal), but some songs with really deep bass like nine inch nails, particularly the song Somehwat Damaged and any other songs with bass drop effects send it in to protect mode. i only keep the gain about halfway and the bass boost i think was at half. these subs arent installed in a vehicle at the moment so i cant go and try anything. it used to be in a 97 nissan XE extended cab and the amp was mounted on top of the box with about 1/4" of space beneath. i do have a horozontal 12v fan that was used on an older amp but i never got around to hooking it up to this one to see if it would work.

    basically im just wondering if im better off going with 1 massive or 2 midsize class Ds or if theres things i can do with this one to keep it cool enough. id like to try and keep this amp. its 5 years old and big and i dont have another use for it and probably couldnt sell it for much. any advice is appreciated. thanks!







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    Re: class AB amp bad choice for subs?

    My first question is did you have any electrical upgrades on your old vehicle (alternator, battery, etc.)? When that voltage drops on the deep bass notes, that could be enough to send your amplifier into protect mode too.

    Also, since your bass bost was at 50%, what were the settings on your HU bass? Did you have the loudness feature engaged or do you own one those head units that has a non-defeatable loudness contour?

    Lastly, how hot was your amplifier when it went into protect mode?

    If you could make it automatically go into protect just by playing your first song, I would point towards your electrical system. Well, until you truthfully answer my questions, I am going to say electrical



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    Re: class AB amp bad choice for subs?

    You wired 2 dual 2's parallel to 1 ohm?




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    Re: class AB amp bad choice for subs?

    turn the **** bassboost off and set your gains properly using the tutorial in the amplifier section.
    Now Class D amps don't typically pull as much constant current as a/b amps, but that doesn't mean that is your particular problem here



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    Re: class AB amp bad choice for subs?

    Quote Originally Posted by terra View Post
    You wired 2 dual 2's parallel to 1 ohm?
    Good catch.... I ate too much and am falling asleep here. I don't think that amp can take 1 ohm stereo.



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    Re: class AB amp bad choice for subs?

    if i'm reading correclty you have 2 subs each wired to one ohm and running the amp stereo correct? what's your voltage at when your bass hits?



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    Re: class AB amp bad choice for subs?





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    Re: class AB amp bad choice for subs?

    Oh boy...



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    Re: class AB amp bad choice for subs?

    yes its a two chan amp, each channel at 1 ohm. its been 7 months since ive dealt with any of this so ive forgotten some details here and there. when the amp is described as say 700w x 2 @ 1 ohm, that means 1 ohm per channel or 1 ohm total load? as far as the temp, the amp would do it like i said on the first song so it would still be cold. ive taken that thing on long drives before and ran it at the same volume i always do for hours on end and everything still worked ok. it wouldnt start cutting out after it got hot.

    the only upgrading i did was get a new battery. optima yellow top. i forget how many amp my alternator was. im wanting to say 60?? my lights would dim just barely when the bass would hit so i didnt think it was worth getting a new one. the bass on the HU was usually 2 or 3 of 6 and i had the loudness setting on high because on any of the other settings it all sounded like ****.

    i think someone before mentioned turning the bass boost off but it seemed like when i did that the bass really just didnt have as full of a sound so i figured running it at half would be ok.

    umm, dont know the voltage when the bass hits. i dont own a multimeter but dont start throwing stones at me as im going to get one tomorrow.




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    Re: class AB amp bad choice for subs?

    Turn off loudness, turn off bass boost.

    Its a 2ohm stereo stable amp, so the min. you should go for each channel is 2 ohms.



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