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Speaker problems

Discussion in 'Amps and Cabs [BG]' started by seanm, Nov 10, 2005.


  1. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    So something is seriously wrong with my Eminence Kappa Pro 12. When I hit a note it there is a "ringing", might be called a buzz but clearer, that goes away as the note gets quieter. It is *very* annoying.

    If I swap in a different cab it does not happen, so the amp and cables are good. It also still happens if I run straight to the speaker so it is not the jacks or the crossover. It also happens with the speaker out of the cab. It also happens with a different bass. Fhewww.

    It does not look creased, but this is to the very untrained eye.

    This speaker has about 50 hours of playing time on it. Except for a quick initial test, it has always been used in parrallel with a CXL-112. In fact, it was bought to give more of a "vintage" vibe to the CXL. When I used it with the CXL, the CXL dominated, so it would probably mask the problem :(

    Any ideas as to what is wrong?
     
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Something is vibrating in the surround. Could be a loose glue bond, could be a piece of schmutz in there. You'll have to pull it out and run a signal into it to track it down.
     
  3. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Thanks, for the reply!

    I am a complete newb when it comes to speakers. Is the surround the foam ring I crudely marked in red in the image? If so, about a 1" section is loose, could that cause the problem?
     

    Attached Files:

  4. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    Yup. Good news is that if that is the only thing wrong with the driver, and assuming the surround it a separate item (like the foam ones tend to be) and not part of the cone, then a good repair shop should be able to put on a new surround for pretty cheap. (I just had a pair of studio monitors that the surrounds basically rotted off of, but all else OK. Repairs were $20 each for testing and surround replacement.)

    In a bass cab, it can get worse, especially if a sealed cab. Due to the surround breach, the cab is no longer sealed, and you can get some really unusual/obscene "farty" type noises with all the air moving through the hole that should be contained in the cab . . . .

    - Tim
     
  5. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Cool! I will try this route first. I hate to throw out a perfectly good speaker.
     
  6. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    If a section of the surround is loose it's a simply DIY fix. Superglue it back together.
     
  7. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Well, that worked! I am back in business!

    Thanks.
     
  8. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    Bill -

    Superglue, or something more flexible? Most of what I have seen used on speaker repair is more like a rubber cement . . . I would think that superglue could create a pretty hard spot in the foam/cone . . . .

    And I guess I was thinking of my older drivers - the surrounds came loose because they had basically deteriorated so much from age, that there was nothing to glue back together. One monitor, that I had not run at much of a level for quite some time, actually started raining black foam bits at one point . . . not pretty!

    - Tim
     
  9. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    You should use rubber cement for repairing a tear in the cone or for reattaching a foam (not cloth) surround to the cone, but the rest of the suspension is assembled with superglue. Rubber cement is way too slow on an assembly line. Everything is glued with cyanoacrylate, which won't set up unless high pressure is applied, and when the parts are properly aligned they hit the glue line with a spray of curing agent and the bond is complete in seconds.
     
  10. Funkengrooven

    Funkengrooven Turn it down? You gotta be nuts!!

    Right on with super glue, although all super glues are not equal..
    A good quality glue is available from your local hobby (model airplanes, etc.) shop in all types of consistancies.
    I use that type on a regular bassis for all kinds of repairs, the cheep stuff does not work very well..
    For paper cone damages I use clear or black silicone sealant..NOT CAULK!!!! .
    I have an old 15 inch speaker with a large triangular tear in the cone that I have repaired with silicone that works fine in my practice amp.
    Make sure you glop BOTH SIDES of the torn cone and mush it in with your fingers to make sure you have the joint filled to prevent the repair from coming undone. Do not run a bead like you are caulking a tub, thin it out around the tear and wipe off any large globs.
     
  11. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    This is all great info which I'm sure will come in handy one day. Thanks guys.
     
  12. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    I used Loctite Super Glue gel. But I also rotated the speaker a quarter turn so that the grill is applying pressure on the problem area. Even if the glue lets go, the grill should keep it from vibrating.

    This info just saved me $170+shipping+tax CDN! So I would also like to say thanks again! :bassist:
     
  13. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    The grill? I think we might be confusing the surround with the gasket. The surround is a moving part of the speaker, so if anything is touching it (ie the grill), it will make all sorts of horrible rattling noises.

    I'd say that your initial problem was in fact part of the gasket coming loose and touching part of the speaker that vibrates to make sound.

    That's actually good news. That's actually not as bad a problem as the surround coming lose.
     
  14. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    You are correct. On the Eminence site they call it a gasket. But it still fixed the problem :)

    It don't think it would have been touching the speaker since the problem area was the top half of the gasket. I *think* the gasket was vibrating against itself since gluing it down solved the problem. Also, as the note died down it stopped. I think it needed a lot of energy.

    Since the speaker was already out, it was a 2 minute fix :)
     
  15. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Most of the time a defective joint will be the one between the surround and the frame rather than the surround and the cone. That's mostly due to the fact the the glue bond between the surround and cone is visible, that between the surround and frame is hidden by the gasket. If the driver is rear mounted to the baffle there's always pressure on the gasket to prevent a defective glue bond from separating, but when front mounted that's not the case, and internal pressures can pop the joint loose, especially if it's a sealed cabinet.
     
  16. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Ok, my original fix did not work :( Two weeks ago I took the cab to practice. It started making noise again and my preamp/amp wasn't working, so I left it there in frustration.

    So last week I carted it back home. This time I did a more thorough check. It was the dust cover! About 1/4 of it was unglued. So I glued it back.

    Tonight's practice was a success! No ringing, buzzing, or other bad noises ... that I could blame on the cab anyway ;)
     
  17. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Since the problem went away and then reappeared in a different place I'd guess that there were two bad glue bonds. The surround was the weaker of the two, so it blew first from internal box pressure. After fixing that the next weakest bond went with the dustcap. Now that you've fixed that another could show up, so I'd lug around the superglue and curing accelerator to a few gigs until I was sure that there were no more bad bonds.