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5E3X2 5E8-A mutant project

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  • 5E3X2 5E8-A mutant project

    Hi Guys;

    My winter soldering project is underway and I thought I'd share it through the process. As usual, I waffled between a variety of ideas and the two surviving contenders were a double deluxe and a 5E something. Then I got to thinking, "Why not both?" At any rate, I've started punching a chassis for a cross between an AA964 Princeton and a 5E8 tweed using a quad of 6V6's. The plate volts are going to be in the 400-410 range so I thought the blackface Princeton controls would give me a little more wiggle room. Plus, the pot arrangement works better (read on).

    I've only shown the preamp in the attached graphic and the values will be similar to the schematics. Because of phasing problems, the switch completely disconnects the unused channel and all caps have a ground reference to avoid popping. Right now I'm going with the 5E feedback and presence setup but there a couple extra lugs on the board if I change my mind. This amp will have a fixed/cathode bias switch on one side of a DPDT standby. 5U4 rectified. JTM45 iron and a choke rather than a resistor between the first two nodes. The donor is a Hammond M chassis and PT -- very cheap on the DIY market right now.

    What makes this possible on the front panel is a little trick I figured out earlier in the year. The common 24mm Alpha pots from Mouser have a stamped back with little fingers bent to hold them on. It is pretty easy to pull the back, substitute a different value phenolic carbon board and crimp it shut again. With dual-ganged pots (not concentric), I can use the same volume, treble and bass knobs even though all three have different resistance ranges. There are some pics on the ampgarage in my same ID under "Strat Switch" in the Dumble section if you are interested.

    http://ampgarage.com/forum/viewtopic.php?t=4423&start=0

    The switch is a mini next to the input where a bright might go. I could use a single grid stopper from the jack to the switch but sometimes it is quieter to have them snugged up to the pin. Separate cathodes on the first tube are probably unnecessary too but this is a pretty empty board. Just three preamp tubes. I do lose the ability to jumper the inputs or tweak both volumes but I seldom do that when I can anyway.

    The rest of the amp is pretty normal. I'm thinking a pair of Neo's or Lil Texans for portability. Standalone verb if needed and it is good to go.

    Comments, questions, whatever ... send 'em along,

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  • #2
    I should have asked in the main post but has anyone tried a 4X10 with the
    5E3X2 platform? thanks again, sh

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