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Out of phase, does it matter?

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  • #16
    This from WeberVST (more respected than the other Weber):

    3. You might find that some vintage speakers, particularly JBL and
    Jensens, were reverse-polarized. This means that a plus voltage
    on the plus-indicated terminal of the speaker will actually cause
    the speaker to move in rather than out.
    You will want to make a note of this or relabel it for your convenience.
    Another point to be made here is that if a person is accustomed to
    thinking a plus on the plus-indicated terminal causes the speaker to
    move in rather than out, it should be noted that this thinking is
    also correct. Again, the speaker is an AC device. The purpose of
    characterizing and marking them is for the convenience of the user to
    ensure they will be connected for proper acoustic phasing.


    I'm pretty sure WeberVST has probably had to deal with this issue due to speaker phasing in multi speaker amps. As is "I need one new speaker for my Super Reverb." I suppose it's possible then that some "batches" of vintage Jensen speakers left the factory with the sticker on the wrong lug? Though I've never heard of a multi speaker amp that had Jensens of differing polarity as I would expect if this were true.

    P.S. Not EVERYTHING in the Gerald Weber books is wrong. He did (does?) work on a lot of old Fenders. Even if his actual tech knowledge is questionable I think his experience may be accurate. But to concede... His tech knowledge is pretty poor.
    "Take two placebos, works twice as well." Enzo

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "If you're not interested in opinions and the experience of others, why even start a thread?
    You can't just expect consent." Helmholtz

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    • #17
      It comes down to being thorough and checking the phasing yourself if you want to be sure. This is especially important if the amp has a mix of original stock speakers and replacements/recones.

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      • #18
        Hi chuck.
        I never said *everything* there is wrong, far from it.
        I *do* watch his videos, I find them funny.
        Never got one of his books, though.
        But he *does* jump to conclusions sometimes.
        Oh well.
        Not boring, definitely.

        As of the mislabelling, *I*, as an example, check speakers one by one, but I can make, what, 20 a day? (3 or 4 per hour)
        Itīs easy to get errors in high production factories, specially because magnetizers work both ways.
        In mine, the magnetizing fixture is connected to the rectifier bank through a *big* 2 pin round lug connector, which can be plugged and reseated "upside down" but needs a special effort; I can easily envision a phase reversal switch at Jensenīs which was flipped for some special job (horn drivers usually are phase reversed) and by mistake stood there, maybe even for days.

        The guy who applies the little stickers, of course, would do things always the same (say, "Red to Right") unless told so otherwise.
        Juan Manuel Fahey

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        • #19
          IIRC, my old JBL D140F did move "backwards" when I checked it. JBL discusses their old reverse-polarity speakers here:

          http://www.jblpro.com/catalog/suppor...=241&doctype=3

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