Removing a magnet cover on a Celestion Greenback/Mojotone Tweed Bassman

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by garytube, Aug 9, 2019.

  1. garytube

    garytube Member

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    I am currently beginning to put together a Mojotone tweed Bassman, which I ordered without the speakers. I have two 10” Greenbacks and two 10” Jensen Tornados on hand, and I was planning on maybe getting 2 more Greenbacks to have 4 of the same speaker.

    I was thinking that it would be an interesting experiment using Celestions, being that I used to have a 90’s reissue Bassman with the Eminence blue frames...which I liked quite a lot, but just wanted to try something different this time around.

    So.... I tried putting the Greenback in the Power transformer position, and there is not enough clearance. It would seem that if I were to take the cover off, that it would clear. Are these just glued on, and could I remove it without destroying the speaker? Or should I just get a Celestion Ten 30 for that position, being that it is sort of similar to the Greenback? Hmm...
     
  2. bluesky636

    bluesky636 Member

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    They should be press fit and come right off.

    My Weber Bassman clone:

     
    Last edited: Aug 10, 2019
  3. garytube

    garytube Member

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    Thanks, will give it a careful try.
    Nice build, btw! Are those 10a150 and 10a125’s?
     
    Last edited: Aug 10, 2019
  4. bluesky636

    bluesky636 Member

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    Good luck.

    I believe they are Alnico Signature 10.

    I have 12" Reissue Greenbacks in my 4x12 cab. I vaguely remember pulling a cover off and it just popped off. Its just plastic.

    [​IMG]
     
  5. Wayne Alexander

    Wayne Alexander Supporting Member

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    If the cover won't pull off, check for a screw in the center, under the name label. That's how covers are mounted on celestion Blues for instance.
     
  6. bluesky636

    bluesky636 Member

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    [​IMG]

    These are vintage Greenback covers. Some sort of adhesive was used. Keep in mind that the magnet is fairly large.

    Celestion Blues are Alnico and a very different magnet structure.
     
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  7. bluesky636

    bluesky636 Member

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  8. garytube

    garytube Member

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    Lol, I currently have the cabinet torn apart for Shellac, so I was going to try it after I get the cabinet together again to see if it clears the power transformer. I did sort of try to get one of the plastic covers off, but they have it glued on darn good. I am slightly concerned that I will bend the skimpy frame. I wonder if I could put a hair dryer on it to soften it...
     
  9. bluesky636

    bluesky636 Member

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    You would probably do more damage with a hair dryer then bending the frame.
     
  10. garytube

    garytube Member

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    Got the cover off, with great difficulty. Hopefully, it won’t have voice coil rub!
     
  11. bluesky636

    bluesky636 Member

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    The frame is steel. I doubt you will have a problem unless you used a vise and screwdriver to get the cover off.
     
  12. garytube

    garytube Member

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    I used a plastic putty knife and my fingers to wrestle it off.
    The magnet is still biggish, but there just may be enough clearance now.
     
  13. garytube

    garytube Member

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  14. bluesky636

    bluesky636 Member

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  15. garytube

    garytube Member

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    Indeed alnico’s without a bell cover would be a better fit.

    So to wrap this thread up:

    1. In the case of my particular Greenback 10” speaker, the magnet cover was very difficult to remove.

    2. The speaker does fit (barely), but the magnet touches the corner of the Mojo752EX power transformer. I believe this is a Heyboer transformer.

    So there it is. I don’t like the speaker touching the transformer. If I was really dedicated, I could probably move the transformer over slightly, but I don’t want to bother with that. I may put a Celestion Ten 30 in that spot or add two in an X position with the two greenbacks. The ten 30 would fit, as the magnet diameter is 3.8” as opposed to Celestion GB being 4.375” with cover off. The Ten 30 is a 95dB speaker like the Greenback, and the freq. response is kinda sorta a “little bit” similar.
    Or maybe I’ll get some of those Emi Allesandro’s...
    Speaker rolling might get spendy!
     
  16. bluesky636

    bluesky636 Member

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    Might try wedging some heavy felt or foam between the magnet and tranny.
     
  17. garytube

    garytube Member

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    Hopefully this will sound ok once I finish the build. The Tornados are about 97 dB vs the 95dB Celestion, so it might work.
     
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  18. bluesky636

    bluesky636 Member

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    Looks like a good setup. Good luck and let us know how it works. :aok
     

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