what does bi pole di pole and tri pole mean?

Discussion in 'Beginners, General Questions' started by Myo K, Apr 15, 2003.

  1. Myo K

    Myo K Stunt Coordinator

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    and how does it relate to speakers?
     
  2. Bob McElfresh

    Bob McElfresh Producer

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    "pole" means fireing in a direction for speakers.
    • Monopole (what most speakers are) fire sound in 1 direction. Often called a "Direct Radiator" because they fire sound directly at the listener.
    • Bipolar speakers fire sound in 2 directions. Often forwards and backwards so you get a back-echo some short time later, but sometimes they fire 90 degrees to each other.
    • Dipolar - these also fire in 2 directions, but usually along a wall and not directly at the listener. They became popular when ProLogic video tapes emerged. The guys at Dolby wanted rear speakers with indistinct sounds like wind/rain/noise, but DID NOT want you to be able to tell where the speaker was. So they wanted a speaker that only bounced sounds off of a wall. These speakers have fallen out of popularity with DVD's and 5.1 systems where you WANT your attention pulled to the speaker location. This is sometimes called a "indirect speaker".
    • Tripolar - these are a bit of a gimmick and non-standard. They often have 2 drivers fireing along a wall like a dipolar, and a third driver that fires out towards the listener like a monopole. Hence "Tri" pole which means 3. Sometimes there is a small switch to change the speaker from indirect to direct.

    Does this help?
     
  3. Michael Reuben

    Michael Reuben Studio Mogul

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    Bob's explanation is excellent as always. I should point out, however, that this question, like so many of the questions asked here, is largely covered in the Beginner's Primer and FAQ:

    Dipole Type Speakers

    The only thing missing from the Primer is any discussion of "tripole" speakers, which, as Bob points out, are non-standard and made by only a few manufacturers.

    M.
     
  4. JamesCB

    JamesCB Second Unit

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    Michael,

    The FAQ probably covers this (I'm too lazy to read it), but you missed one important difference between bipole and dipole.

    Bipole: Drivers on opposite sides of the cabinet are wired in phase, that is they produce the exact same sound from the front and bacj.

    Dipole: The drivers are wired out of phase, meaning there is a cancellation at the side of the speaker.

    Definitive Technology makes bipolar speakers.
    Magnepan speakers are dipolar.
    Miller & Kriesel make tripolar surrounds. (not sure how they work though)

    Note: I dont mean to step on your toes. I just thought that would help. Just my 2 cents.
     
  5. Michael Reuben

    Michael Reuben Studio Mogul

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  6. Bob McElfresh

    Bob McElfresh Producer

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    Oh I understand the phase issue. I just did not want to throw too many concepts at Myo.

    Myo: My advice is this -

    Only consider direct-radiator speakers for your HT system.

    If you hear some bipolar speakers like the DefTechs (which I own and love) and want them, keep this in mind: Bipolar speakers need 2-3 feet of space behind them to work well. If your room/spouse does not allow this, skip the bipolar speakers.

    Hope this helps.
     

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