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Speaker new surround/ test tone ?

Discussion in 'Electronic Design' started by mkr5000, Jun 22, 2013.

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  1. mkr5000

    mkr5000 Guest

    Putting a new surround on a woofer for the first time -- surround has been adhered to cone, now to center it and glue to the frame.

    Don't really want to pull the dust cap and shim the voice coil and was wondering -- could I run a low volume test tone, 1K or so to the speaker and would it then center itself ? hmmm ?
     
  2. Phil Allison

    Phil Allison Guest

    "mkr5000"

    ** The voice coil (VC) will never centre itself.

    You must use a slow setting adhesive on the frame - then you can adjust the
    surround and get the VC coil right in the middle. A low level tone at say
    50Hz will assist you by only sounding clean when the VC is centred.

    Another check is to push lightly at various spots around the edge of the
    cone and find the VC is still clear each time.

    .... Phil
     
  3. mkr5000

    mkr5000 Guest

    Thanks Phil -- if you don't touch the cone it seems to want to "fall in place" and center pretty well by itself? usually the case?

    I may just mark it where it sits and use the slow cure adhesive I have.

    I guess I don't understand voice coils that well -- I was thinking that the field would be equal around the circumference and it would therefore center.

    Guess not. Not a speaker "freak".
     
  4. mook johnson

    mook johnson Guest

    Nope.

    About 10 Amps DC could get it to center. :)...

    As suggested. you could use a low frequency tone (say 20Hz) and get the
    speaker moving pretty good with your fingers holding the surround in
    place. You won't hear any mechanical rubbing sound when you get it
    right. The spider will help you with centering somewhat. Figure out a
    way to clip the surround (maybe clothes pins) to hold it is place the
    second time when you do it with glue.

    You might want to make a ring the fits on the flat part of the surround
    that glues to the frame. You can put this down and use the clothes pins
    to clip that in place.

    Of course once you have it centered you have the woofer straight you
    turn off the tone and let the glue set.

    When doing this you will change he woofer parameters somewhat. if the
    surround is stiffer than the original the Vas will be lower and the Fs
    may be higher. It may sound different that the opposite one when done
    if your only repairing one of a pair.
     
  5. Phil Allison

    Phil Allison Guest

    "mkr5000"
    ** Huh ??

    VCs are non magnetic.


    .... Phil
     
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