Fender BF trem mod in Guitar Player

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by hillbillyjazz, May 30, 2005.


  1. Back in the 90's, Guitar Player magazine had an article on modifying the trem circuit in BF Deluxe, Twin, Super Reverb amps.
    If memory serves, it was essentially replacing the pot for the intensity with a pot that clicked off.
    Does anybody know who the author of the article was?
    Anybody have that issue?
     
  2. Scott_F

    Scott_F Gold Supporting Member

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    I know one of hte mods in Gerald Webers' books talk about disconnecting it completely as he claims it sucks tone.

    So, replacing that pot with one that turns off completely is actually the best of both worlds. You get your trem when you want it and can take it out of the signal path when you wish. Makes sense.

    I'll have to go look for a proper pot and try it.
     
  3. RussB

    RussB low rent hobbyist Silver Supporting Member

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    Only a guess, but I'll say Ken Fischer. There is credit given to him in Gerald Weber's book, "A Desktop Reference To Hip Vintage Guitar Amps"

    I have done this to a couple Fenders...I like it in my '69 Twin
     
  4. Benny

    Benny Gold Supporting Member

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    When I had my Super Reverb, I disconnected the trem completely, per the instructions in the Weber book. I liked it. For me, it seemed to make the amp a little more responsive/touch sensitive, the transition from clean to overdrive was a little smoother, and overall, the amp was a little fatter. I wouldn't say it was an extreme change, but a handful of parameters all went a little bit "better" for my tastes. I think I have a schematic for the switchable trem around here somewhere. I'll send it along if I find it.
     
  5. FlyingVBlues

    FlyingVBlues Gold Supporting Member

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    The article was probably this one: "John McIntyre's Bluesmaker Fender Amp Mod", Guitar Player February 1995.

    FVB
     
  6. Hey FVB,

    That was about the time I remember the article. I do believe that's it.

    Thanks a million.:dude
     
  7. doctorx

    doctorx Member

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    I just did this to my BF Bandmaster. Ted Weber sells a 50k RA post with a switch on the back. When you switch out the trem it results in a noticible boost in gain and clarity. I got two pots so I can do it to my Quad Reverb as well. I recommend it.
     
  8. Terry Buddingh

    Terry Buddingh Member

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    The trem mod appeared in a story titled "Modzilla," GP March '95.
    I wrote about some easy Fender mods, and Bruce Egnater wrote about adding an extra gain stage to your Marshall.
     
  9. WrapAround

    WrapAround Member

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    You'd want to hook up a 1M resistor on the switched pot to avoid a pop when it's turned on, too.
     
  10. doctorx

    doctorx Member

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    Hi Terry, I have a photocopy of that article. Wasn't that the one that had the pot-in-the-speaker-jack NFB mod? I remember... the Soul Control. I had that in my BF Bassman for a while. Seems to me I called you and we talked about it then. Geez, ten years.


    Regarding the 1 meg resistor, where does it go?


    Regis
     
  11. TheAmpNerd

    TheAmpNerd Member

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    A cautionary note,

    I have two amps that had this mod done to them
    and they kept blowing fuses when you turned the
    the amp from stand-by to on.

    Both these amps were vintage black face super
    reverbs.
     
  12. fullerplast

    fullerplast Senior Member

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    That makes no sense whatsoever. Look at the schematic. The intensity pot is completely AC coupled and will have absolutely no effect on standby surge. No way.
     
  13. doctorx

    doctorx Member

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    I was wondering about that. I have had no probs with my trem bypass. Methinks he has other problems?
     
  14. TheAmpNerd

    TheAmpNerd Member

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    WAY -- It doesn't have to make "sense" that is just the
    way it was. It took me a week working on that POS to
    before I rewired the trems "switch" and that resolved
    the problem.

    I've got another wierd as **** problem with a Bandmaster
    head. Maybe you can give me some points on it.

    I've subsequently read something about not doing this
    trem mod on vintage amps too. I can't recall where it was,
    but if I run across it again I'll post the reference here.
     
  15. fullerplast

    fullerplast Senior Member

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    Anything that blows a fuse needs to make sense. Opening the trem pot connection will not make the fuse blow. It is simply decreasing the signal load by eliminating the 50K pot path to ground, as though the amp did not have a trem circuit at all.

    Something else was happening with your amp, you just don't know what it was. This is a perfectly safe mod and has been done for years.
     
  16. TheAmpNerd

    TheAmpNerd Member

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    Please, don't tell me that. It did. Don't ask me why or how
    because I still don't know.

    Look for my post soon on the Vintage Bandmaster.

    This is puzzling me and perhaps you or someone can
    shed some light on it.
     
  17. RussB

    RussB low rent hobbyist Silver Supporting Member

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    AmpNerd,

    Did you do the work yourself?

    Was other work done at the same time?

    If you re-connect the trem, does it still blow fuses?
     
  18. TheAmpNerd

    TheAmpNerd Member

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    Yes.
    No.
    Yes. When I did, yes, it resumed.
     
  19. doctorx

    doctorx Member

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    Ok, lets go over how the mod is done.

    Here is the layout of the Bandmaster

    This is how the mod is done:

    1. Disconnect the wires from the 50k RA Intensity pot.
    2. Remove the pot.
    3. Install new 50k RA Intensity pot with SPST switch attached.
    4. Solder brown wire to center lug as before.
    5. Solder left lug to pot casing as before.
    6. Solder Yellow wire to one side of switch.
    7. Solder short length of new wire from other side of switch to right lug.

    Yer done.

    If do this mod correctly with no shorts or misteaks, there is no way it will blow a fuse. You have other unrelated issues with the amp. Have other mods been done to it?
     
  20. TheAmpNerd

    TheAmpNerd Member

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    I know.

    I did NOT do the mod.

    I UNDID the mod.

    The amp works find now and there are no further
    blown fuses. Sorry I was not clear about that.

    And yes, I've performed this mod, too.

    Just giving a heads up. Things in electronics
    do not ALWAYS work out they way they are
    supposed to.

    Anyone who's dabbled in this stuff should know that.
     

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