An idea discussed with Rod Coleman, Andy Evans and others in DYIAudio forum which still is evolving. The purpose is to increase the output driving capability of this preamp using a cathode-follower stage. A bonus is to provide the filament bias using the cathode-follower valve filaments:
Lookin good!
I’m using the heaters of a 6c45pi and 6e5p in the phono section of my preamp for the 12v bias on the 4p1l line stage.
I think lots of advantages, the heat produced is used and the idh tubes get a great supply with the coleman boards. and saved me another power supply (20v 440ma series chain with 45pi and pc86 on previous incarnation)
Hi Enzo,
Yes, absolutely. A great idea to implement. I’m limited here given the CX301a heaters are 350mA. I could add a resistor in parallel and use higher filament current and open the possibility to use a 6c45pi, 6e5P, 6n6, etc. I could do that in the future…
Ale
or use 300ma series tubes like morgan jones did and shunt them to 350ma, i,m using 39r to shunt the 6c45pi to 600ma, i think the pc86 had 27r to shunt up to the 6c45’s 440ma so many variations to try!
enzo