Stock KLF-20 woofer voice coil rub. Anybody seen that?

Discussion in 'The Klipsch Korner' started by grindfix, Feb 13, 2019 at 1:35 PM.

  1. grindfix

    grindfix Full time hobby Subscriber

    Messages:
    679
    Location:
    New Albany, OH
    I wonder if anyone ran into this. Two out of four woofers are not centered. Voice coil rubs badly in one and slightly in another one. There is no indication that woofers were re-foamed. Am I dealing with improperly centered spider or just surround? Spider does not seem to be detached as I’ve seen in Klipsch subwoofer drivers due to basket rusting. I was able to peel off the surround from the cone and can attempt to re-center using low frequency signal but would like to hear opinions on how to verify spider alignment first.
    Thanks
     

     

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  2. bandit88

    bandit88 New Member

    Messages:
    11
    Location:
    Wisconsin
    I had a pair for KG5.5s that had that issue. I think after being driven hard for a while the coil distorts and then rubs. You could try rotating the woofers 180 degress and see if they get better. Sometimes they kind of sag after a long time of not being used.
     
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  3. moray james

    moray james Super Member

    Messages:
    3,115
    Location:
    Calgary on the Bow
    a good professional re cone shop should be able to re build your four drivers for you to all match and be very close to stock. These are very good sounding drivers and they are worth rebuilding. The cost of a re build is going to impact your decision. Finding new replacement drivers is going to run you around the same amount of money. You will have to consider the cost if you have to ship the drivers to have them rebuilt. You could part out your speakers and look for a new set of KLF20 with no issues this time. I think that would be the way that I would go. Good luck what ever you choose to do.
     
  4. RobRoy

    RobRoy It's just stuff - but fun

    Messages:
    2,822
    Location:
    Central Kentucky
    Being a bass player, I've destroyed more speakers than I care to admit to. There are two types of damage that can happen.: Thermal and mechanical. For me it was always thermal.

    Mechanical is when you push a woofer so hard that it physically breaks something. Try running some hip-hop through a thousand watt amp into a five inch speaker with a good sized magnet. Crank it up to full power and see what happens. :)

    In my case, it was always thermal. The last time was doing an outdoor gig on a patio on Mercer Island, Wa on July 4th in the middle of the day. Playing Stranglehold (constant, solid bass) with a heavy chorus effect. There was no wall behind the speaker and I was trying to compete with two guitars. It was a 2x12 cabinet. 1200 watt bridged amp. One woofer went dead, and a few seconds later the other one did. The next day I cut the spider and the cone and pulled out the voicecoil. The windings fell off like so many chunks of spaghetti.

    But usually what happens is that it just overheats enough to warp the voicecoil, causing it to rub.

    BTW, what killed mine was an entire song with pretty much full power bass. If it had been intermittent bass notes and in the higher ranges it would be fine. That day I discovered why many woofers have heat sinks around the magnet structure. Thank God it was the last song of the gig.
     
  5. grindfix

    grindfix Full time hobby Subscriber

    Messages:
    679
    Location:
    New Albany, OH
    I'm too far into rebuilding them to part them out. I got dust cap off yesterday and ordered adhesive that guy from Simply Speakers recommended. I'll try to shim the voice coil and see if resetting surround will take care of this. I hope that those coils are not heat damaged. Thanks for your thoughts!
     
  6. RobRoy

    RobRoy It's just stuff - but fun

    Messages:
    2,822
    Location:
    Central Kentucky
    I'll just throw this out: Unless a pair of speakers have a very exotic or severely custom woofer, I'll usually (actually, always) go to a place like newark.com and get a similarly spec'd (or similar quality) woofer of the same size and I'm golden. And sometimes it's better than golden. It's also a lot easier than re-coning.
     

     

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