phase reversal pedal?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by lonestargtr, Sep 4, 2006.

  1. lonestargtr

    lonestargtr Silver Supporting Member

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    Jul 15, 2005
    Location:
    Nashville, TN
    Hi,

    I'm not technical enough to figure this out or even if it's possible, but I run a multi-amp switcher and was wanting to run a "dry" combo amp along with it, but the combo amp is out of phase with two of the amps in the switcher either way I switch the phase. Only my Matchless has a phase reverse switch, so my question is:

    Is there a small box that I can run to reverse the phase either into the inputs of the amps or from the speaker outs that will switchably reverse the phase while isolating the ground to keep from making an awful squeal?

    I first tried to rewire the speaker cables from those amps backwards but got a god-awful squeal because I was basically creating a terrible ground loop with the other amps. Anyway, any help would be appreciated.

    thanks,
    Mike
     
  2. sysexguy

    sysexguy Member

    Messages:
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    Joined:
    Sep 17, 2002
    Location:
    St-Sauveur, QC Canada
    Firstly, if reversing the speaker out phase causes squeals like that, please turn everything off asap.

    The various amplifier's speaker outs cannot share a common ground at any time. If you are wiring a stereo cab, be sure to use insulated jacks like the cliff jacks that come on a Marshall cab (and most others) or switchcraft types mounted in individual plastic cups (like say a /13).

    Once that is sorted, you may continue to optimize your rig's performance. The ground pin should not be lifted on any amp and instead, any ground loops should be eliminated through proper cabling and isolation. A box such as a Lehle P Split or a Littlelabs PCP would be a good investment and assure safe, noise free performance with minimal tweaking required.

    Andy
     
  3. TwinandTwang

    TwinandTwang Member

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    Sep 29, 2005
    Check out the Barber Launch Pad
     
  4. lonestargtr

    lonestargtr Silver Supporting Member

    Messages:
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    Joined:
    Jul 15, 2005
    Location:
    Nashville, TN
    thanks guys. The launch pad definitely looks like it would work. It still does more than I need, but it's not terribly pricey for all that it does, so it's definitely a possibility. Thanks,

    Mike
     
  5. JJman

    JJman Member

    Messages:
    992
    Joined:
    Mar 12, 2006
    Location:
    New Jersey
    If switching the speaker wires created a squeal it was likely related to the negative feedback wire. If you switch the wires at the output tranny this will switch the speaker wires but will also switch the feedback wire. You would need to switch only at the jack (or speaker plug/wire) to avoid the feedback wire.
     

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