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Loudspeaker Phasing.

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With a smallish, say village hall, type P.A. system using several speakers of different makes, what is the easiest way to ensure correct passive speaker phasing. I mean how do we ensure that they are all pushing or pulling the air at the same time and are not out of phase?

I am concerned about using two different types of amplifier as well. How do I confirm correct phasing?

Z.

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  • 0

    by convention, the 'positive' labelled terminal on a loud speaker is the one that when connected to a DC source pushes the cone outwards when positive.

    Just occasionally you come across one that is reverse wired.

    Using a small battery, if need be with something in series to limit the current, such as a torch bulb.

    1. Place one speaker wire to the positive (+) terminal of the battery.
    2. Briefly place the other speaker wire to the negative (-) terminal of the battery. 
    3. Notice which way the speaker moves as you make this connection.
      1. If the speaker moves outward, then the speaker wire connected to the positive (+) terminal of the battery is the positive (+) wire.
      2. If the speaker moves inward, then the speaker wire connected to the negative (-) terminal of the battery is the positive (+) wire.


        Fancy phase testing boxes are available but that is an easy way if you can see the cone move.

        If y9ou get it wrong, and stand between 2 speakers driven by the same signal, one if which is mis-phased and listen to some music with a wide spectral range, and then reverse the connection, the one that sounds 'right' is right. Nothing is damaged if it is wrong, apart from the musical experience,

    Generally labelling of connectors is standardised on all modern amps in the way that a positive pulse in the inputs will come out of the amplifier wth the positive speaker  terminal positive. An asymmetric waveform has to be used to verify this properly as a time delay and inversion look the same on a symmetrical waveform.

    Mike.

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  • 0

    by convention, the 'positive' labelled terminal on a loud speaker is the one that when connected to a DC source pushes the cone outwards when positive.

    Just occasionally you come across one that is reverse wired.

    Using a small battery, if need be with something in series to limit the current, such as a torch bulb.

    1. Place one speaker wire to the positive (+) terminal of the battery.
    2. Briefly place the other speaker wire to the negative (-) terminal of the battery. 
    3. Notice which way the speaker moves as you make this connection.
      1. If the speaker moves outward, then the speaker wire connected to the positive (+) terminal of the battery is the positive (+) wire.
      2. If the speaker moves inward, then the speaker wire connected to the negative (-) terminal of the battery is the positive (+) wire.


        Fancy phase testing boxes are available but that is an easy way if you can see the cone move.

        If y9ou get it wrong, and stand between 2 speakers driven by the same signal, one if which is mis-phased and listen to some music with a wide spectral range, and then reverse the connection, the one that sounds 'right' is right. Nothing is damaged if it is wrong, apart from the musical experience,

    Generally labelling of connectors is standardised on all modern amps in the way that a positive pulse in the inputs will come out of the amplifier wth the positive speaker  terminal positive. An asymmetric waveform has to be used to verify this properly as a time delay and inversion look the same on a symmetrical waveform.

    Mike.

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  • 0 in reply to mapj1

    Thanks Mike.

    Z.

  • 0 in reply to mapj1

    Go on then I`ll ask.

    Mike, how does noise cancelling work, does it alter phasing?

    If you are in a noisy environment and you have equipment to pick it up and send it out to counteract the effect, will it silence/reduce it or will it enhance the effect to the point of squashing your brain thru your eardrums?

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