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    Looking for a post regarding polarity.

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    WntrMute2

    Posts : 101
    Join date : 2010-11-21

    Looking for a post regarding polarity.

    Post by WntrMute2 on Mon May 21, 2012 2:37 pm

    After witnissing a friend correct a significant audible problem by reversing polarity of the tweeters, I remember in my distant memory that Bob had a post regarding a test for this. It involved hooking up a battery as a test and seeing which way the drivers moved. Anyone remember this? Or could shed some light on this topic?

    Bob Latino
    Admin

    Posts : 2413
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Looking for a post regarding polarity.

    Post by Bob Latino on Mon May 21, 2012 3:49 pm

    Hi,

    The test really works only for cone drivers. I don't know that the test will work with a tweeter which has only slight movement in and out. You could *try* the test with a tweeter ?

    With a cone driver what you do is use a 1 1/2 volt battery and connect the positive terminal of the battery (through a wire) to one of the two speaker terminals and the negative terminal of the battery to the other speaker terminal. Just allow the connection for about a second. As you do this look at the speaker cone. If the speaker cone moves OUT you have the proper phase for that speaker. If the speaker cone moves IN during that brief second the speaker phase is reversed.

    A short note here .. Some amps and preamps due to their circuit design give a reverse phase on their output. All VTA amps do not reverse phase. They are phase correct. If you use a VTA amp with a preamp that has reverse phase then the amp will be given the signal as a reverse phase and the output of the VTA amp will be in reverse. I had someone with a 1990's Conrad Johnson preamp that tell me that the output of his VTA amp was in reverse phase but further investigation showed that his preamp was the cause of the reverse phase.

    To check the phase of your music system plug an interconnect into any of your preamp's high level inputs (CD, FM Aux etc.). Turn the volume down on the preamp. Remove the grille cover on your speaker. With a jumper wire connect the positive end of your 1 1/2 volt battery to the center pin on the other end of the interconnect and the negative end of the battery to the outer shield of the interconnect for a second and look at the woofer cone of your speaker. If the cone moves OUT your system is phase correct. If it moves IN your system has reverse phase. If you can't see the cone move turn the volume up on your preamp until you can clearly see cone movement. If your system proves to have reverse phase all you have to do is reverse your two speaker connections at the speaker. Your music system will now be "in phase".

    Bob

    hawaii.ken

    Posts : 157
    Join date : 2012-01-31

    Re: Looking for a post regarding polarity.

    Post by hawaii.ken on Mon May 21, 2012 3:55 pm

    Testing polarity of the tweeters with a battery is a chancy move. Depending on the tweeter you may or may not be able to detect any "movement" and you risk blowing out your tweeter.

    Correct speaker polarity also depends on crossover design. Your ears should be the final judge.

    http://www.diyaudioandvideo.com/Tutorial/Crossover/

    http://www.diyaudio.com/forums/multi-way/212559-phase-alignment-based-method-designing-multi-way-speakers.html

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