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Thread: The walpurgis fix for buzzing and rubbing speakers!

  1. #1
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 28,426
    I'm Geoff.

    Default The walpurgis fix for buzzing and rubbing speakers!

    Sometimes, a driver voicecoil may become misaligned in the magnet gap and rub against either the pole piece or outer face of the gap. If your bass driver is buzzing or has a binding coil, this may help. I've offered this advice several times and provided a remedy to a few people. I've used this trick myself successfully on occasion. Lets face it, if you have a dodgy bass driver, you have nothing to lose by trying it.

    One bass driver. I this case, an 8" KLH.




    This is the important bit. The area where the back of the cone meets the rear suspension spider (the corrugated part).




    Using a finger poked through the chassis opening, work the cone back and forth on its suspension whilst pressing it forward (across) just in front of the join with the rear spider. Do this all the way round the cone. If the coil is fouling, you will feel it rubbing. Do this as many times as it takes you to identify the point at which it rubs most.




    Once you are sure where it is rubbing most, mark this point with a felt tip pen.



    Next. Feed reasonably strong elastic bands through the speaker chassis openings and around the back of the cone so that they pull in the opposite direction to the felt tip pen mark you made on the chassis, ensuring the bands pull firmly, but not so hard as to risk causing damage and secure the bands in place using sticky tape or tying them or as I did using a paper clip.






    Then, use a hairdryer set to hot through the chassis openings and onto the rear spider all the way round. This relaxes the spider and allows the coil to move over slightly.



    Set the dryer to cold and go round the spider again. This 'sets' the new coil position.

    Remove the elastic bands and hopefully you will have a cured drive unit. Occasionally you may need to try this technique a couple of times before you get it spot on!


    Note: This will not work if the coil has been overheated and is binding due to swelled lacquer nor will it work if the coil is distorted and no longer circular.





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    Last edited by walpurgis; 07-05-2017 at 09:38.
    Mr. Tact!

    Main system: MMs/ADCs/Low output MC's/One rare Japanese SUT/One scarce British phono stage/various tonearms/hefty Japanese DD TT and hefty Japanese BD TT and small British BD TT. 4 CD players/2 jitter buster/2 DACs/Valve buffer. TVC stepped attenuator or valve pre-amp or solid state pre-amp. Current dumping power-amp or either of two Class A SS power-amp or Class A EL34 valve monos or big Japanese (part Class A) integrated. Big dual concentric speakers/Smaller dual concentric speakers/Two way British compacts and full range speakers, amongst others. And too much more to list!

  2. #2
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 36,405
    I'm Grant.

    Default

    Made this a sticky for you Geoff. think it will be a great help for folk
    Regards,
    Grant ....

    I've said it before and I'll say it again: democracy simply-doesn't-work
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  3. #3
    Join Date: Dec 2015

    Location: vancouver

    Posts: 642
    I'm danilo.

    Default

    Clever trick indeed.. Wonder if it has permanence?
    Though in truth many would simply throw the worthless driver out.
    My audio bits: Thorens / diy phono, CD/dvd player(s), diy pre, F6, Tannoy Golds in my boxes / my xovers, and of course all strung together with basic diy Wires
    Lots of Cd's, yet more audio files, a couple of hundred semi worn Lps.

  4. #4
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 28,426
    I'm Geoff.

    Default

    Quote Originally Posted by danilo View Post
    Wonder if it has permanence?
    From experience. It does.
    Mr. Tact!

    Main system: MMs/ADCs/Low output MC's/One rare Japanese SUT/One scarce British phono stage/various tonearms/hefty Japanese DD TT and hefty Japanese BD TT and small British BD TT. 4 CD players/2 jitter buster/2 DACs/Valve buffer. TVC stepped attenuator or valve pre-amp or solid state pre-amp. Current dumping power-amp or either of two Class A SS power-amp or Class A EL34 valve monos or big Japanese (part Class A) integrated. Big dual concentric speakers/Smaller dual concentric speakers/Two way British compacts and full range speakers, amongst others. And too much more to list!

  5. #5
    Join Date: Dec 2015

    Location: vancouver

    Posts: 642
    I'm danilo.

    Default

    Worth remembering knowledge then.. thank you
    My audio bits: Thorens / diy phono, CD/dvd player(s), diy pre, F6, Tannoy Golds in my boxes / my xovers, and of course all strung together with basic diy Wires
    Lots of Cd's, yet more audio files, a couple of hundred semi worn Lps.

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