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Does anyone besides Allen do a Bassman conversion like this?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by jpervin, Jun 29, 2006.

  1. jpervin

    jpervin Supporting Member

    Jan 13, 2005
    Frazer, PA
    This is a mod that David Allen of www.allenamps.com offers on his website. I got in touch with him to see if he still does these mods and he's backed up through the summer with orders for his own Allen amps, so he's suspended any mods or repairs on Fender amps until further notice.

    Does anyone else besides Allen do a similar Bassman mod such as this?


    Here's the info from the Allen website:

    "BassmanĀ® Head conversion - there are lots of 65-70 BassmanĀ® heads with the odd AB165 circuit which was quite a departure from traditional Fender circuits. The BASS channel is not really voiced well for guitar and is often not used. This conversion rebuilds the entire circuit board so the NORMAL channel is the more desirable AA864 circuit (about like the NORMAL channel of a Super Reverb) and the BASS channel becomes a really cool lead channel with a tweed/Plexi flavor to it. The DEEP switch goes between the huge cathode bypass capacitor associated with the 5F6A Bassman to the much smaller capacitor used with the Marshalls. This channel has an extra gain stage, is more aggressive and has more harmonics for a great lead channel. You can use an A-B switch to switch between the two channels with each having its own volume and tone controls. It makes a much more usable amp for guitar. Many end up preferring the BASS channel to the classic tone of the NORMAL channel. The conversion is $199 plus anything else that might be needed as part of normal service such as new filter capacitors, tubes, grounded power cord etc. I have done several of these and they are very popular. The modifications are reversible and there are no holes drilled or controls not properly labeled."
  2. hasserl

    hasserl Member

    Oct 24, 2004
    So Cal
    I'd also say there are probably a couple hundred amp techs out there that could do this same thing. But if you want to support the techs that support TGP I think Mike at KCA, Tim Swartz of Swarty, or Todd Shock of Wakarusa Amplification should be able to handle the mods easily.
  3. Texsunburst59

    Texsunburst59 Member

    Mar 4, 2005
    Texas Gulf Coast
    My Amp guy does the Allen mod. He's been talking to David Allen about the mod and David says he no longer will do them and will concentrate on building his amps. I've got one (Allen modded) bassman from David and the other 2 were modded by my amp guy.If you're interested in talking to my amp guy, e-mail and I'll give you his contact info.Here's my modded Bassmans:

    My 69' and 66' Bassmans:


    My 71' Bassman:

  4. Texasamp

    Texasamp Member

    Jun 18, 2006
    Houston, Tx
    Great mod, and is very easily done. Time consuming considering you have to build 12 amps in the next 2 to 3 months. A walk in would be no problem, just the shipping back and forth for a mod that has very little bench time, I try to stay away from until I am caught up.

    Darrell S.
  5. TheAmpNerd

    TheAmpNerd Member

    Sep 23, 2004

    Many folks do that sort of thing.
  6. 59model

    59model Member

    Mar 7, 2003
    Lake Charles LA
    Mike from KCA does that mod too. He`s a great guy and stands behind his products, so I wouldn`t hesitate a moment contacting him if I were considering this. Good luck!
  7. Blue Strat

    Blue Strat Member

    Aug 2, 2002
    Sterling, VA (not far from Washington DC)
    Thanks for the plug. I'm not taking in any new amps right now due to overload in my tube business.

    This is a pretty common mod and I would avoid using any tech who doesn't know about it.
  8. karmadave

    karmadave Member

    Apr 7, 2005
    Bay Area
    Ron Ott does these conversions too. He did a '66 Bassman, for KBR, with EL34's instead of 6L6's. Best Bassman I've ever heard! Bass Channel sounds more like early Marshall. Normal Channel is classic Fender...


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