Speaker question... What is speaker rub?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by toneman335, Feb 14, 2008.


  1. toneman335

    toneman335 Member

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    Read in a posting where someone stated a speaker has a "slight rub".

    . What exactly is that and its symptoms?
    . What causes it?
    . Can it be fixed without a recone if its so called "slight"?
     
  2. JJman

    JJman Member

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    It's when the moving voice coil rubs against the pole piece/magnet/front plate in the pics.



    You can sometimes verify it's happening by gently pushing on the cone and feeling/listening for any rubbing. It sounds "harsh" when playing. At least when I had it in the past.

    [​IMG]




    [​IMG]
     
  3. Rosewood

    Rosewood Member

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    The voice coil has a very small area to work in and if it gets off center it will sometimes rub. This can be caused by uneven torque on the mounting screws causing the frame to warp or sometimes the cone is just out of shape from age,etc. It sounds like a fuzz mixed in with the note and usually ends up with a fried voice coil. If you place all five of your fingers evenly around the dust cover(not on the dust cover) and gently push inward you can usually hear or feel it. If you have a speaker like this try loosening the mounting screws or nuts and torque them evenly to see if it cures it. I have actually gone as far as uneven torque to try and reshape the frame.
     
  4. Rosewood

    Rosewood Member

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    Sorry, I type so slow.
     
  5. toneman335

    toneman335 Member

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    Thanks very heplful replies and diagram. Just one more question...other the mentioned cures such as a retorque is a recone the ultimate "fix" or can something else be done? In other words if such a speaker is sent to a repair facility chances are it will be reconed?
     
  6. Rosewood

    Rosewood Member

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    Yea at that point I think a recone is the next step. It gives them a chance to clean the gap and start with a fresh coil, cone and spider.
     
  7. bluesy

    bluesy Supporting Member

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    ..in the first diagram, does the rub occur between the "front plate" and the "former"; or between the "coil" and the "pole piece"? Or both? Just trying to understand.
     
  8. bluesy

    bluesy Supporting Member

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    I meant between thefront plate and the coil; or between the former and the pole piece.
     
  9. Rosewood

    Rosewood Member

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    Inside or outside of the coil and could be both, the gap is very small. That's why you can over tighten the screws and cause a scrub, the gap is small and the voice coil/former is centered in the gap. If the frame is bent, or the cone gets flexed or wet it could be enough to throw it off center and rub.
     

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