This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Wednesday, August 17, 2016

Wampler Cranked AC

Another amp emulation overdrive from Wampler that's supposed to sound like (you guessed it) a cranked Vox. This one has been discontinued, but was very popular. It's very similar to the Plexi-Drive, but doubles the transistors and there are a few component changes. I've added trimmers to help bias the J201s.


  1. What's the purpose of doubling the transistors?

    1. I would assume the reason was for the tone. Not really sure otherwise.

  2. It assumes that each pair of transistors should be matched?

  3. I had a 1st gen CrankedAC, when it was an etched circuit board, not machine-fabbed.
    A couple of points:
    1) Mine had a 2.2uF elec cap in parallel with the 1K resistor at the Q1/Q2 pair
    2) Mine didn't have the power filtering this one does; just the 47uF cap

    Everything else looks pretty much the same.

    I cloned my original one recently, with a few of mods:
    1) Used all 2N5457s - a little more open/less gain than J201s, which I find to be more compressed/higher gain
    2) Pulled the two .0022uF caps in the filter at the end - gives more chime/treble, makes the tone control more useful
    3) Used a 250K pot for gain - the stock config with J201s and a 500K gain pot was a bit much - the 250K allows me to dial in the low-med gain tones I wanted.

    Tried the Vox Afterburner (CoolTube series), Runoffgroove Britannia & English Channel, Menatone TBIAC, Boss Combo Drive, Catalinbread Galileo clone (admittedly a good circuit) and Tech21 DoubleDrive. The CrankedAC is the only one that uppermid/treble chime I was looking for, with a good range of usable overdrive.

  4. Sir, this one is verified, sir!
    I use the exact components listed above.
    Awesome as usual!