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Phasing using multiple rigs

Discussion in 'Amps and Cabs [BG]' started by TheSuzie, Apr 18, 2006.

  1. Nick mans multiple tube rig post got me thinking..

    How do you make sure all those speakers are moving in phase when you have all those different rigs running together? Something I always wondered about WRT multiple rigs.

    Engineering types - Is there a standard for whether or not an instrument amp is inverting or non inverting? I'm not talking about eq induced phase shifts but about the basic design of all of the gain and power stages.

    Would I have to use a multi channel scope to check this and then reverse the polarity of the speakers on one amp if I found that one amp inverted and another did not? Any way to check this without a scope?

    Is my conclusion that this may be an important factor totally wrong?

  2. My advice is set all speaker cabs to Plus-Red-Forward.

    Connect the Black speaker terminal to the Negative side of a battery. When you make the Plus terminal connected to the Red wire, the cone moves Forward (toward the audience).

    Those with bass horns, Forward means into the horn throat.

    Change the wiring inside the cab so a standard cable (1/4" or Speakon) moves in the standard direction. Tip is the Red for 1/4" and +1 is Red for Speakons.
  3. Thanks bgavin, that takes care of the cabs - but now what do I do about the multiple heads. That is the part that that seems tough, especially since most amps are not DC coupled. In the thread I referred to Nick man seemed to be talking about using multiple tube heads at once and that adds a whole new dimension.

    Any easy way to tell if a head is basically an inverting or non-inverting amp?

  4. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    If one amp is inverting, there will be a point when the two systems cancel one another as you twiddle the volume controls. It's pretty striking. As an experiment, make a reversed speaker cable and try it out.
  5. Good idea, fdeck. Sometimes I am too laboratory oriented to think of a simple answer, one reason why I asked here.

  6. nysbob


    Sep 14, 2003
    Cincinnati OH
    I run multiple tube amps and have never had a problem. Proper speaker phasing is the first thing I check when sorting out a system.

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