The Crate tube amp conversion is done

I’m calling it the Nervosa. It’s sort of based on the 5F6A Bassman but I went way off the reservation in quite a few places.

Here is the schematic:

And here is a video

A longer write up will be along soon.


  1. it sounds good , at least the Marshall part , for me the bassmans have to little gain , i want to know if one can use 2 gainstages ( maybe a little terror front ) and a catodefollower mosfet to get enough gain into a 6l6 output . keep up the good work ,

  2. I like you work and have built 3 of your amps. On the Nervosa schematic, I dont understand the tone stack schematic. When the switch is to the left, yoy have the 56k slope resistor and the .02 bass cap in the circuit and that looks good. When you flip the switch to the right, it looks like you short out the .02 bass cap. If you were to put a .1 cap between the common of the switch and the other teminal then you would have .1 +.02 for a total of .12 mfd. And the slope resistor woul be 56k +47k or 103k. I plan on building the Nervosa and wanted to make sure I understand the tone stack. I want you to know that I really enjoy yor website an appreciate yor hard work. Thanks.

    • Glad you like the web site James.
      I thought about doing the tone stack like you mentioned but I decided to move the .1 mid cap to right after the cathode follower and before the tone stack. The whole tone stack is in series with the .1 cap so when the .02 cap is shorted it’s still following the .1 cap so .1 is still the maximum capacitance there.

      Some older Fenders also did something similar.

      Doing it this way also keeps voltage off the switch.

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