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DIY blown speaker diagnosis and repair

Discussion in 'Amps and Cabs [BG]' started by Funkateer, Dec 30, 2006.


  1. Funkateer

    Funkateer

    Jul 5, 2002
    Los Gatos, CA
    I fear that I have blown a speaker in my Epifani UL310. Nasty buzzing/flapping in lower register when played at a decent volume. I have already tried a new battery in my bass, so I don't think its that. Assuming that it is a blown speaker, how does one go about figuring out which of the drivers is gone? Am I gonna need a helper?
     
  2. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Denton, TX or Kailua, HI
    fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
    Be sure when you test that the head is NOT sitting on top of the cabinet.
    I once thought I had 2 bad drivers in a 2x10 and shipped it for repair. The 2x10 was fine. My Pre-amp tube was shot, and made noise when the cabinet it was sitting on vibrated at the right frequency. :p

    Test the cab with a spare head, too.

    Basically, I'd find the lowest level at which the bad sound appears. Put your ear near each speaker (wear earplugs, if needed). You should be able to hear which one (or more) speakers are rattling. You can play and sit on the floor in front of the cab. :ninja:

    Remove the grill and repeat (carefully!). Don't touch the drivers. Make sure all the speaker bolts/screws are very tight. Reattach grill and tighten it well, being sure all the spacers and washers are on correctly.

    You might also check to be sure all the speakers are connected. I had a wire come loose in a 4x10, and thought I had killed a driver. There was rattling from one of them, too. Once I fixed the wiring, all was well.

    Worst case is contact the builder and go from there. Good luck! :cool:
     
  3. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    If you have the grille off, also very carefully, evenly push each cone in and out gently - if you feel or hear any dragging, that indicates a bad driver.

    - Tim
     
  4. Trevorus

    Trevorus

    Oct 18, 2002
    Urbana, IL
    Also look at the surround and make sure it has no cracks.
     
  5. jimbilly

    jimbilly

    Apr 19, 2006
    I've successfully tested a lot of speakers by gently pushing the cone and feeling for roughness. You can move it just a tiny bit and if the voice coil is burnt or damaged you'll feel it as scratchi-roughness, a good speaker should feel similar to pushing in the side of a balloon.
     
  6. Funkateer

    Funkateer

    Jul 5, 2002
    Los Gatos, CA
    After I identify the blown driver, can I remove it, and retest the cab with the remaining drivers to confirm that I've identified the bad boy? Any chance of damage to either amp or cab if volume is kept at a reasonable test level?
     
  7. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    Don't necessarily remove it - just disconnect it. The big open hole will radically change the cabinet's tuning, and it would probably sound "off" to you with the hole open . . . . but as long as you keep reasonable volumes, you should be OK.

    - Tim
     
  8. If the speaker is flapping and farting under power it will do the same without the wires connected but possibly to a lesser gegree as it will act like a passive radiator.
     

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