1960A Marshall 4X12 cabinet problem

Discussion in 'Amps and Cabs' started by Lerxt, Feb 20, 2006.

  1. Lerxt

    Lerxt Member

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    Anybody else ever have this problem with a Marshall 1960A 4X12? When I play a clean tone on the low E string, on frets five through seven (especially seven), I get a loud buzzing or resonating noise coming through the cab. This is also noticeable on frets one and two of the A string, but not as bad.

    This loud buzz is noticeable even at pretty low volumes, but gets much worse as I turn up to normal stage volume.

    My first guess would be a bad speaker, but I run this cab in stereo and this buzzing/resonating happens on both sides of the cab. Seems unlikely that I'd have a bad speaker on each side.

    Also, I tried plugging my rig (Peavey 50/50 Classic tube poweramp, Digitech 2120 tube preamp) into a Soundtech PA speaker (1X15 plus a horn), and was able to play on the sixth string/seventh fret with no problems. So I'm pretty sure it's the cab, not my rig.

    Any thoughts on what's going on here?
    Thanks,
    Jim
     
  2. bvmjethead

    bvmjethead Member

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    Loose cabinet joints?

    Loose speakers?

    Blown speakers?

    To much of a certain frequency in the tone? Try turning some tone knobs......

    I don't know....
     
  3. glman

    glman Member

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    I had a very similar problem when I first got my 1960 ( Greenback ) equipped cab andsolved the problem as follows.
    I checked that no speaker cables inside the cab were touching the cones.
    I also made sure that the back panel was secure and free from vibration by placing some extra (soft) padding on the wooden bloch in the centre of the cab that supports the back panel so that when the back panel is secured it has a tighter fit and therefore doesnt vibrate on certain resonant notes
     
  4. HeeHaw

    HeeHaw Member

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    Check the baffle and see if it is loose as well. The 1960 a is held together with some flimsy stuff.
     
  5. Scumback Speakers

    Scumback Speakers Gold Supporting Member

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    This I can attest to. Later model JCM 900 and later cabs have alot of MDF in them, notably:
    1) The entire back panel
    2) The baffle board mounting rails

    I've heard several people gripe about the construction properties of the later 4x12's, and have to agree with them. One client said his cab was so bad that he had to dowel every baffle board mounting screw hole AND move up to a #10 x 1 3/4" screw as well (typical Marshall screws are #8 x 1 3/4") to make it solid. He's plenty PO'd.

    For reference, my demo cab was an early 80's JCM 800 1960A cab, and it still had the pine/poplar/whatever solid wood the screws mounted to, but I guess that changed in the 90's to MDF. The JCM 800 had MDF for it's back panel, and for it's logo mounting plate (big whoop there, right?), but not critical spots like the baffle.

    The early to late 70's cabs had MDF back panels, but everything else was solid wood (I know, I stripped one this morning to recover/restore) everywhere else.

    You get what you pay for, that's for sure.

    As for the noise you're hearing, check your cab and your speakers. I've got a problem like this with a major cab supplier right now, and I'm trying to narrow it down to either a damaged cab or damaged speakers...it could be either at this point, so I'm trying to isolate it.

    Good luck!
     
  6. billdurham

    billdurham Member

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    I would toss out another test for you....does it do it with a different amp?
     
  7. thecajunboy

    thecajunboy Member

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    One of your speakers is probably loose. I had one doing the same thing. Drove me nuts for a while as I spent most of my time dicking around looking for amp caused issues, and loose hardware on the outside.
     
  8. rockstah

    rockstah Member

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    did you check for blown speakers? - speaker rub? - slightly moving the speaker back and forth from the back - gently and evenly push the speaker paper back and forth form the back of the speaker...if it makes a scratching noise you have a speaker rub and the speaker probably needs to be reconed - something to check anyway.
     
  9. zadiqof

    zadiqof Member

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    I got that with 2 1960b cabinets I had, but never with a 1960a or ax model. I assumed it to be ****** speaker baffling.
     
  10. StoneAge Cabs

    StoneAge Cabs Silver Supporting Member

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    LERXT...BVM makes a very good point regarding the possible loose cab joints. MAJOR P.I.T.A. if these need attention.
    Another possibility: check the cab side handles to see if they are secure. Assuming they are the plastic, they are notorious for coming apart/loose....resulting in rattles & buzzing.
     
  11. HeeHaw

    HeeHaw Member

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  12. Stormin

    Stormin Supporting Member

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    I seriously doubt it's a blown speaker. Most JCM900 and newer cabs have a "tuned" 2x2 piece of wood going from the middle of the 4 speakers in the front to the back. On these cabs, this piece of wood is too short to actually reach the back plate of the cab. When you hit the low notes, this thing resonates like a tuning fork.

    Glue a small piece of foam on the end of this piece, and then place the back of the cab on. Drive a screw into the 2x2, and the problem is solved.

    ...Stormin
     

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