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power 2 subs with 5ch amp?

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  • power 2 subs with 5ch amp?

    hey need some advice...im abit of a noob

    iv got a 3000w 5ch amp which works out to be 500w to 4chs and 1000w to a sub ch, the sub cha is the the only ch that has a xover so the only ch that can power a sub(60-160hz), we have 2 subs at 1000w @4Ω cause we hooked it up to the amp wer only getting 500 each @ 2Ω... we can bridge the 4 speaker chs into 2chs which means 1000w each... so what iv heard is that if we have the signal goin into the sub ch so was get a signal out between 60-160hz then we bang a massive resistor on the out put we can take it back into the speaker inputs and duplicate it so we get 1000w @4Ω on each sub....

    ..will this work???

  • #2
    the short answer is yes, the long answer is not really a great idea. The idea of a 5 chan amp is to provide 2 or 4 high power uncrossed (on most amps) outputs with a separate mono sub output for a complete system in 1 amp (front and rear amped mid/highs and a sub)

    A decent 5 channel amp is still bridgeable on chan 1-2 and 2-4 usually for a 2 sub combo but you require a crossed over input either from your head unit or a separate cross over to provide your filter. If the amp is really solid, you could consider using dual voice coil subs and bridging channel 1-2 for 1 sub at 2ohms and likewise for channel 2-3, that way you are running a 2 ohm impedance on each sub for a lot of bang and you let the 5th channel go to waste. if your 2 subs are 4 ohm single coils, then wiring them paralel on your sub channels bridge will give you a 2 ohm output mono from that channel which is perfectly safe but will waste the other 4 channels unless your using them for highs/mids.

    If your ONLY powering subs, trade or sell the 5 channel or religate it to powering your mids/highs and get yourself a couple big bang mono block amps to power your pair of subs if its SPL your looking for, if its a decent sound curve you want then do a decent job crossing over your input into the pair of bridged channels for a nice clean 2 ohm bridged output.

    Basically Im recommending getting the right tool for the job your trying to do and not muck about with something that may or may not give the results that you want.

    Also remember that if your adding resistance to a Bridged connection, your lowering the overall impedance to something lower then the smallest amount of resistance (ohms law) and your liable to be disappointed with the results especially if you inadvertantly drop your output impedance under 1.5ish ohms or so and snap crackle and pop your amplifier.

    If you drop the brand/model of the amp/sub combo your running and what your goals are for the speaker system perhaps I can help further ? saying you have a 5channel amp is very generic and doesnt tell me what those channels are capable of handling under load.

    Personally if I were powering a sub system with a 5channel amp that had no built in cross over for chan 1-2 and 3-4 Id get myself a good in dash EQ/cross over to feed those inputs a dash controllable signal/gain/freq and bridge those 4 channels for a nice clean pounding pair of subs and let the 5th channel go to rot. OR I would religate the 4 channels to powering mids and ignore the sub channel completely and replace that amp in my plans for subs with a system of amps or a single amp more appropriate to the task of pounding subs.

    Pete

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    • #3
      the amp posted below. im helping a friend out, its not mine i woulda got a mono amp but the guy in the shop told him to get this.... iv only jst looked at the specs for it the manual wasnt very helpful, all it told me was that it was 1000w bass so i presumed that it was 500w each other channel.

      so going over what i have done is put the 2 1000w 4ohms subs in parallel so 1000w at 2ohms(the manual said this was okay but... i cant find the power it puts out at 2ohms anywhere..)

      it seems there would be no point trying to power the sub with the stereo channels cause they put out bugger all power any way..
      this is the circuit i was talking about.
      http://www.epanorama.net/circuits/speaker_to_line.html

      the amp
      Earthquake TD5 3000 Watt
      http://www.earthquakesound.com/index...mart&Itemid=82

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      • #4
        that speaker to line level schematic is for amps that only take low level inputs(rca inputs)

        that would not be for what you are trying to do-- i actually don't know of any resistors that would take 1,000 watts of power(i know of 100 watt load resistors, meant for bench testing amps, so sq is not a concern)-- even if i did, the amount of heat generated would probably require water cooling just to keep it from starting on fire...

        if your friend just recently bought the amp, return it..

        i never recommend to ever seriously buy a amp that does not have rms power ratings listed. rms ratings are much harder to fake--granted they can be faked, but it is much harder to do.. usually, most companies that take the time to test, and display their amps rms ratings usually means that the amp that you get will come close to matching the rated specs-- at 12-14.4 volt input, and the rated resistance on the output...

        peak ratings could really be anything-- they might have achieved those peak ratings at 0.5ohms, and 40v power input-- there is nothing that says that they didn't use procedures like that...(even if you could do this, i doubt the amp would survive for any more then a couple seconds/minutes)

        i recommend purchasing amps that were have CES ratings on them-- while there are still ways to fiddle with the numbers, any amp that has CES certified ratings will at least have a much more even playing field when it comes to comparing different amps.
        My OLD 2001 Mitsubishi Eclipse GT:
        "The Project That Never Ended, until it did"


        next project? subaru brz
        carpc undecided

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        • #5
          you have to be VERY careful getting "what the guy in the shop" recomends. Its always best to know what you want and what you want it to do before you buy something. The simple reason is this, the guy in the shop wants to make a buck. If his margin of profit is highest by selling you the 5 channel (Ie cost 99 bucks , retail 400 bucks instead of a pair of monoblocks that each retail for 400 bucks but cost is 350 bucks) hes going to make more money selling you the 5 channel and maybe have you come back to ad what you really need later.

          Im out of time in my day but ill check the setup you posted later in the morning and reply in detail tonight

          Pete

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