Pics of the beast
Posted:
Sat Oct 11, 2008 9:27 amby chopdr230
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I am loving this amp . Is there a way to make a 45 get set go ???
Here
Posted:
Sat Oct 11, 2008 9:31 amby chopdr230
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45s or any power triode should work fine
Posted:
Sun Oct 12, 2008 7:31 amby EWBrown
Very nice! I like the "machine turning" effect on the chassis.
The GSG board design allows for LOTS of design flexibility, and having the power tube sockets off-boared makes using any suitable power tubes that much easier.
45s should work, just change (increase the total resistance) the cathode resistors to provide the appropriate biasing / plate current. If the overall B+ is too high, the two paralleled 180 ohm resistors in teh B+ string may have to be changed. The changed cathode resistors may have to be mounted off-board, or at least elevated away from the board, as theyre may be some increased heat generation.
I hjave one GSG in "interrupted" progress which will use 6CK4s, the cathode resistors will be around 620 ohms for these, from my initial calculations, though they may have to be "massaged" a bit after the fact...
From some previous 2A3 SET experience, the cathode resistor in that design (originally 1100 ohms) would be increased to 1500 ohms, and the series resistor in the PSU was also increased to 1500 ohms, in order to accomodate 45s, but then that was a somewhat different circuit, and voltage/current ratings, so YMMV.
FWIW, in one of my 6B4G versions, I replaced the 180 ohm paralleled resistors with another choke, that I happened to have on hand. Helps reduce any residual PSU ripple.
/ed B