Well, we had to start somewhere and simulating the valve performance is a bit hit and miss at such low anode voltages.
Even the capacitor values in the PS section needed some thought.
In short, the only way forward was to prototype and change component values as required.
An oscilloscope helps here in addition to a DMM 
Here's the original prototype that assured us that it is possible to make a suprisingly good performing amp utilising a valve, yet be cheap, easy, and reasonably electric shock free.
The transformer is a very cheap 0-15-0-15 unit available in the UK and other EU countries.
After altering some of the PS capacitor values, CCS resistor value etc. etc. we ended up with something that was stable and fun to listen to for extended periods.
Yes, it applies some compression but that's part of its charm, and it would be a rather sterile sounding amp without the 12AU7 (ECC82) altering the sound the way it does with 40V anode volts.
I for one hope that folk attempt to build this amp, suggest/implement improvements, alterations, whatever ....
Now to go build a "proper" one.
posted 10-25-2005 12:35 PM CST (US) 
