The Amplifier
Design of the preamp is loosely based on a Marshall 18 Watt, here implemented with an additional gain stage (V2a) and using 6021 subminiature dual-triodes. It is a typical design found similarly in other tube guitar amps. In the current configuration the preamp has a lot of gain but is not capable of delivering loud clean tones. With humbucking pickups it is probably impossible to avoid distortion unless the guitar volume is turned down.
Output amplification is produced by one half of a 6021 subminiature dual-triode. This tube can be biased to 1 W according to its datasheet. While this may not seem like much it is enough to annoy your neighbours and way too loud for late night playing.
The one-knob tone control works reasonably well though I mostly put it on a sweet spot at about 11 o'clock and let it set there.
FONTE: http://www.jjs.at/electronic/class_a_subminiature.html
