by Brinkman Wed Nov 18, 2009 4:03 pm
This is one of the rare occasions where a compromise is optimal. By compromise I mean only replace a few resistors rather than all. Specifically, I'd replace the grid resistors (R1/R2, R33/R34, R35/R36) with carbon composition types. By the way, the Kiwames are rumored to be re-branded KOA/Speer resistors which can easily be obtained more affordably via Mouser.
Additionally, the plate load resistors (R11/R12, R19/R20, R21/R22) could be upgraded to non-inductive wirewound types such as Mills. All these suggestions are per Morgan Jones' excellent book, Valve Amplifiers. And I really mean excellent. It's awesome.
Otherwise, if all I had was the PC board and no parts, I'd get PRP resistors for the rest of the metal films. They are inexpensive (to an audiophile) 1% metal film resistors which a lot of folks swear by. It's probably hype, but it helps tweakers sleep at night, so it's okay. Also, you can chase your tail experimenting with the coupling capacitors (C5/C6, C7/C8). I'm currently using Jensen paper-in-oils, but on a different driver board. I still enthusiastically recommend the VTA board though.
Have fun.
