David McGown wrote:
Walt,
Interesting about the multi-megaohm resistors.
Well back to the amps. Both are done and in the system and working great. I can say that a Williamson front-end, for all the initial trouble I had with it, seems to MUCH better sounding than the same amp using a Mullard topology. Really no contest. It gets tone and space. Gain structure is right. The sound is complete divorced from the speakers. The extra power (50W) compared with the stereo EL34 triode Williamson amp (18W or so) is apparent by better dynamics and lack of strain. Though the little Williamson does have a certain sweetness to the sound. Everything needs to break in, new resistors, coupling caps, solder joints, etc.
A few things to note:
I used Speer 2W and 1W carbon films resistors available at Mouser for most of the signal path. These are the same resistors as Kiwame, I can say that even though they are 5% rated parts, the resistors off the same spool are tightly matched to each other, better than 1%. Matched parts are critical for the concertina phase splitter and driver plate resistors.
The previous version (Mullard) used a 9 pin mini (12AX7/5751/12AY7) for the first tube. I used a 6CG7 instead of an octal 6SN7 to avoid punching a larger hole for an octal socket.
David
That's good to know about the Speer. I like WKiwame but they're a little scarce right now.