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Fender Super Twin Footswitch

Discussion in 'Amps and Cabs [BG]' started by Charley Umbria, Jan 12, 2012.


  1. Charley Umbria

    Charley Umbria I'm Really a Drummer Supporting Member

    Jan 28, 2011
    Rock City, TN
    I'm interested in building a footswitch for my 1975 Fender Super Twin amp, but information is very hard to come by. From what I've been able to gather, the original footswitch had stomp buttons for punching the 5-band EQ in and out and for turning the distortion on and off. The unit also had a slide switch that activated a volume boost in conjunction with the distortion footswitch. Here's what the footswitch looks like:

    FenderEQDist03. FenderEQDist02-S.

    I'm hoping one of our resident Super Twin owners/fans might be able to give me some gutshots of their footswitch, or just some more info.

    I've tried contacting Fender and they were kind enough to send me a schematic for the Super Twin Reverb, which they said was very similar. They did not have a schematic or other info on the footswitch, aside from some part numbers. From looking at the Super Twin Reverb schematic, it appears that the ring to ground connection on the distortion/boost tip-ring-sleeve (TRS) plug is in series with the amp’s distortion switch. Inserting the plug opens the path to ground, and then the footswitch closes it.

    The boost is a little more complicated. I’ve read that the boost switch inserts a 39 ohm resistor in parallel with the 100 ohm resistor in the negative feedback circuit, so it's not a simple open/close stomp switch like most amp pedals.

    My eventual goal is to build a two-button footswitch, controlling EQ and boost, and ignoring the distortion “feature”. I've attached a copy of the amp's schematic. Any help out there?
     

    Attached Files:

  2. RobbieNuke

    RobbieNuke

    Jan 22, 2008
    Baltimore
    I have one for sale on eBay now.
     
  3. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    Hi Charley,
    i never use it, but i just found mine last week. if you want, i'll take some pics of it and post them for you.
     
  4. Charley Umbria

    Charley Umbria I'm Really a Drummer Supporting Member

    Jan 28, 2011
    Rock City, TN
    Thanks for the responses, guys. I was actually able to find one a couple of months ago...through a Telecaster forum, of all places. A guy had a new-old-stock Fender footswitch that he couldn't identify. Turned out to be the one for the Super Twin!

    I popped mine open and, as suspected, it's pretty much three switches and a resistor. One of these days I'll work out a schematic and post it for posterity. In the meantime, it's fun, but as John mentioned, you don't need it very often.
     
  5. jumbodbassman

    jumbodbassman Supporting Member

    Dec 28, 2009
    Stuck in traffic -NY & CT
    Born Again Tubey
    is there a way to turn off/on the EQ without a footpedal
     
  6. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    not that i'm aware of.
     

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