Replacing the speaker in an old-is GK MB150S

Discussion in 'Amps and Cabs [BG]' started by Jeremy Kahn, Apr 29, 2019.

  1. Jeremy Kahn

    Jeremy Kahn

    Apr 29, 2019
    My MB150S started farting when I play a low F. I opened it up and found that the speaker is supported on a post which is screwed to the back of the cabinet, on top of which is a rubber foot attached to the post with a screw, which had worked loose. I tightened it up and put it all back together and it seemed to work fine for a couple of months. Then it failed again, and this time I found that some kind of rubber attachment to the back of the speaker had degraded. I ordered a new speaker from Thomas.de but found that it didn't have the rubber parts. Does anyone know where I can get the rubber parts?
     
  2. Wasnex

    Wasnex

    Dec 25, 2011
    I would shoot GK an email.
     
    Ductapeman, cnltb and RyanOh like this.
  3. Jeff Bonny

    Jeff Bonny Inactive

    Nov 20, 2000
    Harrison Mills
    There’s also a speaker gasket that is absolutely essential. More than one of those amps has been sold dirt cheap because the gasket had rotted and the amp developed rattles that couldn’t be identified. For the $15-20 it probably costs these days I’d replace that too. That amp is still in production isn’t it? Contact GK.
     
    Ductapeman, Dabndug and Wasnex like this.
  4. Jeff Bonny

    Jeff Bonny Inactive

    Nov 20, 2000
    Harrison Mills
    It’s been over 10 years since I contacted them for MB150 parts but they responded pretty fast as I recall and hooked me up with what I needed.
     
  5. Jeremy Kahn

    Jeremy Kahn

    Apr 29, 2019
    Sorry, just understood your reply. The gasket is a stick backed foam thing in several parts? Came with the speaker. Thanks.
     
    Jeff Bonny likes this.
  6. Wasnex

    Wasnex

    Dec 25, 2011
  7. Jeremy Kahn

    Jeremy Kahn

    Apr 29, 2019
    Yes, that's what I got. But I need the grommet thing to go on the back of it.
     
  8. two fingers

    two fingers Opinionated blowhard. But not mad about it. Inactive

    Feb 7, 2005
    Eastern NC USA
    Yeah contact GK. And the speaker gasket is a ring that goes between the wood of the speaker baffle and the speaker itself. It should line up with all of the screw holes that hold the speaker in place. It should look something like the pic below. (Not the one you need. Just an example from a Google search of speaker gasket.)
    images.jpeg.jpg
     
  9. Jeremy Kahn

    Jeremy Kahn

    Apr 29, 2019
    Thank you. One came with the speaker.
     
  10. JimChjones

    JimChjones

    Aug 6, 2017
    SE England
    Is that normal folks? I'm trying to envisage it and I think failing, but it sounds like nothing I've ever seen.
     
  11. BassmanPaul

    BassmanPaul Inactive

    I admit that it doesn’t sound like anything I have seen either. Perhaps the OP is describing it poorly.
     
    Last edited: Apr 30, 2019
  12. kpc

    kpc

    Apr 6, 2011
    GK sells all of their speakers on their website.
     
  13. JimChjones

    JimChjones

    Aug 6, 2017
    SE England
    A photo of this post and foot arrangement might help. As I say I don't understand your description at all, but I wonder if it might be something non-standard a previous owner has put in might be better removed. Unless of course you've had it from new...
     
  14. mmbongo

    mmbongo I have too many basses. Supporting Member



    That is just a normal speaker, no extra plates or screws or anything. What are you referring to that's 'extra'?
     
  15. Wasnex

    Wasnex

    Dec 25, 2011
    This is the area I interpreted as possibly an added plate. Appears elevated, like its glued on after the fact.

    Just trying to figure out what the OP is describing as missing. I.E. if the speaker does not look like this, perhaps he didn't get what he ordered.


    upload_2019-4-30_12-16-49.png

    Here's an image of the rear of the amp. Note, the screw in the middle of the back panel. It's not clear to me whether this screws directly into the center of the speaker or some other "post" that is between the rear panel and speaker. On my EV SX300 cabs, the horn drive is screwed directly to the rear panel, but this would seem unnecessary with a 12".

    [​IMG]
     
  16. nilorius

    nilorius Inactive

    Oct 27, 2016
    Riga - Latvia
    What size speaker it is ?
     
  17. mmbongo

    mmbongo I have too many basses. Supporting Member

    That part of the speaker is called the 'back plate'. Quite essential to the construction of the speaker, as it holds the magnet assembly together. So definitely not added on, every ceramic magnet speaker has that.


    [​IMG]
     
    Wasnex likes this.
  18. Wasnex

    Wasnex

    Dec 25, 2011
    I think you're probably correct. I thought possibly that was a mounting adapter glued to the back plate.