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Thread: Sub Question

  1. #1
    RIP 2021 SEAWOLF97's Avatar
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    Question Sub Question

    scene: I am running two (2) M&K 12 inch powered subs and sometimes L88's on the number 2 BGW amp in my system...with only 1 set of amp outputs, a switch box is involved.

    the subs have dual inputs ..hence, I think, dual VCs ...and just different variants of the same sub, pretty close.

    question: do the subs function just as well with just one i/p ?? Is it feasible/ desirable to run the left channel o/p to 1 sub and right channel to the other ?
    thus eliminating the switch box ? (and orphaning the L88s) ?

    Could dual inputs just combine internally , and not always mean dual VC's ?
    Some kind of happiness is measured out in miles

  2. #2
    Administrator Mr. Widget's Avatar
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    Since they are self powered I doubt the two inputs have anything to do with number of VCs... I bet it has to do with outputs if your subs have internal crossovers. Most all subs have one input for LFE and a pair to be used if you want to sum a mono signal or if you are using the sub's crossover to limit the range going to your mains.

    How are these inputs labeled?


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  3. #3
    Senior Member Fred Sanford's Avatar
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    Quote Originally Posted by SEAWOLF97 View Post
    scene: I am running two (2) M&K 12 inch powered subs and sometimes L88's on the number 2 BGW amp in my system...with only 1 set of amp outputs, a switch box is involved.

    the subs have dual inputs ..hence, I think, dual VCs ...and just different variants of the same sub, pretty close.

    question: do the subs function just as well with just one i/p ?? Is it feasible/ desirable to run the left channel o/p to 1 sub and right channel to the other ?
    thus eliminating the switch box ? (and orphaning the L88s) ?

    Could dual inputs just combine internally , and not always mean dual VC's ?
    Model #s would help- my V3B is a SVC with dual line ins and dual speaker level ins. So is my Velodyne sub, and my Canton sub.

    Have you tried running line level to the subs, and simply turning them on or off when desired? Do you have level-controlled line outs? Couldn't they also just take a speaker or line-level feed from your main amp?

    je

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    Moderator hjames's Avatar
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    Don't know if it would help - the plate amp in my M&K Volkswoofer was gutted by the PO, the woofer in there now is M&K 12" woofer with single VC - and of course I have the B-380 across the room. For a while I ran my LFE channel to an RCA Y cable and that fed the L & R inputs of my Citation 22 Amp - I ran distinct outputs (not bridged) - L to the B-380, R to the M&K and it played very well ...
    If your M&Ks have amp-level inputs, maybe you could do the same with one of your BGW amps ...
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    both of the subs are pretty basic .... speaker line inputs with a volume control knob ...

    Quote Originally Posted by Fred Sanford View Post
    Model #s would help
    Have you tried running line level to the subs, and simply turning them on or off when desired? Do you have level-controlled line outs? Couldn't they also just take a speaker or line-level feed from your main amp?
    je
    they are both marked "The Volkswoofer" ...there are only speaker INs & OUTs ,,not even power switch or light , assume ALWAYS ON.

    mebbe will try L to one and R to the other from just one channel.

    LATER: Just tried it ..L to one R to the other ...seems to work fine
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  6. #6
    Senior Member Fred Sanford's Avatar
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    Quote Originally Posted by SEAWOLF97 View Post
    both of the subs are pretty basic .... speaker line inputs with a volume control knob ...



    they are both marked "The Volkswoofer" ...there are only speaker INs & OUTs ,,not even power switch or light , assume ALWAYS ON.

    mebbe will try L to one and R to the other from just one channel.

    LATER: Just tried it ..L to one R to the other ...seems to work fine
    I'm still not sure why there even needs to be a second power amp for the subs if they're both self-powered...couldn't they simply take a feed from the main speakers/primary amp? If they have speaker-level outputs, they might also have a high-pass filter in place which would benefit your mains by remove the sub-range frequencies.

    je

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    it all worked out very well , I was concerned that the subs set up for dual speaker line inputs may be different with just 1 i/p , but no difference....

    it all sounds a little more solid ...I'm thinking that running 2 total leads to 2 speakers instead of 4 leads to 2 speakers may have raised the impedance level ?

    load is 2 8ohm (assume) speakers instead of 4 8ohms ? ... this dual vc (or not) throws my calcs.
    Some kind of happiness is measured out in miles

  8. #8
    Senior Member Fred Sanford's Avatar
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    Quote Originally Posted by SEAWOLF97 View Post
    it all worked out very well , I was concerned that the subs set up for dual speaker line inputs may be different with just 1 i/p , but no difference....

    it all sounds a little more solid ...I'm thinking that running 2 total leads to 2 speakers instead of 4 leads to 2 speakers may have raised the impedance level ?

    load is 2 8ohm (assume) speakers instead of 4 8ohms ? ... this dual vc (or not) throws my calcs.
    If the subs are self-powered (have their own amps inside the boxes) they shouldn't present any significant load to the main full-range amp. Running a second power amp for self-powered subs should be unnecessary- it's really providing a signal for the subs but the actual power it puts out is wasted.

    je

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    Quote Originally Posted by Fred Sanford View Post
    If the subs are self-powered (have their own amps inside the boxes) they shouldn't present any significant load to the main full-range amp. Running a second power amp for self-powered subs should be unnecessary- it's really providing a signal for the subs but the actual power it puts out is wasted.

    je
    OK...understood. Both subs were turned all the way up , gainwise ,when on a speaker box with the L88's......then I removed the L88's and replaced them with the Walsh F's and all of a sudden the subs were WAY overdriven,,,had to quickly reduce gain on both and now get same o/p turned almost off.. weird ?

    OK...now dont understand.

    L88 is 8 ohm. Walsh F is 4 ohm and you say powered subs are negligible impedance .
    Some kind of happiness is measured out in miles

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