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OK, I have several subs that I want to wire up 4ohm/8ohm ?'s

Discussion in 'Audio' started by jjlaughner, Nov 5, 2002.

  1. jjlaughner

    jjlaughner 3/4 ton status

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    OK, I have several subs that I want to wire up 4ohm/8ohm ?\'s

    I have two 10" MTX Black Gold subs <4ohm> wired in with a memphis st16-300 (150RMSx2@4ohm) amp. My recent purchases include two 8" and two 12" MTX Black Golds all 8ohm.
    SO my question is what do I need to run the 8ohm subs? Can I use a regular 4ohm amp? I've heard running 8ohm subs on a 4ohm amp is louder/more powerful, How So?
    What is the coversion between WATTS and ohm in this case? I guess I'm just trying understand what the 8ohm sub on the 4ohm amp difference is? /forums/images/graemlins/deal.gif
    ????4ohm WATTS hitting on my 4ohm 10's verses the same 4ohm WATTS hitting on a set of 8ohm 12's???? /forums/images/graemlins/confused.gif
     
  2. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: OK, I have several subs that I want to wire up 4ohm/8ohm ?\'s

    Jeremiah,

    I think you've got it backwards... /forums/images/graemlins/smile.gif

    If you look at the power rating on an amp at 4 ohms, but actually load it with an 8 ohm speaker....the power will be LESS. It sort of makes sense, since the speaker is RESISTING the amp more....it will take MORE power to make it move. So if the amp was 150 Watts/Channel at 4 ohms, odds are that you will get something like 75 Watts/Channel at 8 ohms. It's not exactly that simple, but as the load increases, the power of the amp will be diminished.

    As a solution, you could wire the 8 ohms subs in parallel on a single channel to reduce their "apparent" ohm rating closer to the 4 ohms that your amp prefers...
     
  3. BozoWise

    BozoWise 1/2 ton status

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    Re: OK, I have several subs that I want to wire up 4ohm/8ohm ?\'s

    This is a few questions in one. First off what subs are you wanting to run off what amp? Are you asking to suggest a new amp for the 4 new 8 ohm subs. I would not suggest running the 8" and 12" off the same amp because the crossover freq is not near the same. As far as your current setup with the Memphis amp and the subs. Are you running the speakers stereo or bridged? Clarify a bit on your question and I would be happy to help you out; I'm just a bit lost on it right now.
     
  4. jjlaughner

    jjlaughner 3/4 ton status

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    Re: OK, I have several subs that I want to wire up 4ohm/8ohm ?\'s

    /forums/images/graemlins/grin.gifI want to run all my subs on the same amp 300watt amp /forums/images/graemlins/grin.gif
    JUST KIDDING
    No right now I'm running two 10" MTX black gold's (4 ohm subs) stereo off a memphis 16st-300 (150rms x2).
    I just bought a set of 8" Black Golds and they turned out to be 8ohm, I also just got a set of 12" black golds and they are also 8ohms.
    I'm wondering what advantages do the 8ohm subs have if any? And can they be ran from a standard 4ohm amp if I bought another 16st-??? amp for looks(???=wattage and what I would need to push the 12's in either stereo or bridged)?
    Right now I have Alpine CDA-7894 and I'm running the amp off the sub woofer output (wait... I shouldn't have that? subwoofer output running stereo thats probley not working right) OK, I'm going to switch the 10's to the rear output (for stereo) and put the 12's on the subwoofer pre-amp out so I guess I could run them bridged...Sorry I'm thinking... What do you think?

    Pics time
    [​IMG]
    dash speakers are the Memphis PR35's with caps (front channel off cd player
    [​IMG]
    mids are MTX 3000 components with tweets (rear channel off cd player)
    [​IMG]
    10" MTX Black Golds stereo with the Memphis 16st-300 300watt amp (currently on the subwoofer preamp out)
    I romoved the factory 4x10's because they where blown and I hooked the components up to the factory wires in front of the rear bench.
    I used 2 gauge power to a distribution block, fuse is 12" from battery, ground cable is either 2 or 0 gauge and a distribution block, grounded to the rear frame (ground me down a spot and bolted on then painted it). Battery and motor have their own grounds to the frame as do the lights.

    I'm wanting to ADD the 2-12" subs into the mix and Maybe the 8" subs if I can find room to mount a third amp
     
  5. BozoWise

    BozoWise 1/2 ton status

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    Re: OK, I have several subs that I want to wire up 4ohm/8ohm ?\'s

    That amp in the picture I believe is a mono block sable down to 2 ohms load. That would make since with the two current 4ohm speakers.

    You could run all four of the 8 ohm subs off a similar amp just try and get steup up and I would not suggest doing this as the 8 and 12 need much different crossover freq.

    Shoot me an email with the amp that you are wanting to use and I can get you the wiring info. Or just run a pair off any amp bridged as all amps are stable to 4 ohm mono minimum
     
  6. jjlaughner

    jjlaughner 3/4 ton status

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    Re: OK, I have several subs that I want to wire up 4ohm/8ohm ?\'s

    WOW, thanks for the reply, I wonder why I didn't see this is my email? I posted another ? in here and seen this one had a reply.
    Yes the Memphis 16st-300 is stable to 240watt @2ohm.
    I am not sure on the whole 2,4,8 ohm stuff. My 10" MTX Black Gold's are 4 ohms, the 8's and 12' I have are 8ohm. If I got a 16st-200 (100x2@4 ohms and is also 2ohm stable) would that be enough for the 8" subs and then stepup up to the 16st-400 (200x2@4ohm also 2 ohm stable) for the 12" subs?
    Do those get wired in parallel or series?

    THANKS for the help again! /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/thumb.gif
     

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