is there a way to tell if my speaker is firing backwards?

Discussion in 'Beginners, General Questions' started by Anthony_I, Oct 29, 2003.

  1. Anthony_I

    Anthony_I Stunt Coordinator

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    i have a switch on my amp which can bypass the phase adjust circut, i was told that because of this i need to crosswire the amp (red to black and vice versa) for it to work properly (IE fires out when its supposed ot and back when its supposed to) But it looks to me like it is firing backwards when the bass hits...... no matter how it is wired and despite weather or not the phase circut is bypassed.
    this may simply be that im not able to determine which way it is moving however.

    If i play test tones though it does seem as if it is moving outwards and not inwards.

    so is there a way to tell which way it is moving?
     
  2. GrahamT

    GrahamT Supporting Actor

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    It make NO difference as long as both speakers have the same phase.
     
  3. Wayne A. Pflughaupt

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  4. GrahamT

    GrahamT Supporting Actor

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    Follow Waynes's tip to check polarity but you don't know how the track was mixed.
    If it looks like the cone moves inwards first thats fine, its just a rarefaction. You can't tell the difference between a compression and a rarefaction. They sound the same.
     
  5. ChrisWiggles

    ChrisWiggles Producer

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    The cones are moving so fast, you're not gonna be able to see how it moves, other than that it's moving. Gotta follow wayne's advice.
     
  6. Mark Shannon

    Mark Shannon Screenwriter

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    on a side note, on the back of my Sub, is says Phase: 0º and 180º...what exactly is this switch for?
     
  7. Anthony_I

    Anthony_I Stunt Coordinator

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    well i dont have any other speakers for it to be in phase with right.... well some very shitty ones that arent even meant for this.
     
  8. Allan Jayne

    Allan Jayne Cinematographer

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    The 0-180 switch is a phase reverser, you can use that instead of exchanging the speaker wires at the terminals.

    If you can get any audio test disk, Video Essentials also has audio tests on it, play a tone under 100 Hz. Exchange the speaker wires to one speaker at a time and leave the wires connected the way that gives the louder sound.

    Once in awhile if your front and rear amps are not the same make and model, the phase of the audio going to the various speakers is not 0 or 180 and you can't tell which way is louder. If your amp(s) don't have speaker phasing controls with settings in between (almost all don't) just leave the speakers as-is.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  9. John Garcia

    John Garcia Executive Producer

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    Phase adjust is not to compensate for amps, it is to handle issues with sub placement within a room, relative to the main speakers. Phasing issues can cause cancellation of frequencies between the sub itself and standing waves in the room or phase differences with the mains.

    Graham is correct, it doesn't make any difference as long as both speakers are wired the same.
     
  10. Anthony_I

    Anthony_I Stunt Coordinator

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    My phase is continuiously variable, and it has a switch to BYPASS the phase adjustment altogether.... it isnt a simple 0 or 180 switch.
     

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