by EWBrown » Mon Dec 03, 2007 7:58 am
I have experimented with 6AV5GAs in triode-strapped mode, and it indeed behaves very closely to a 6B4G, 2A3 (or 6A5). The screen grid G2 can be connected directly to the plate, or through a 100 to 1000 ohm, 2W resistor.
I set up a "bread board" circuit using an octal relay socket, and a Heathkit variable power supply and tried both fixed, and cathode (1K 10W WW) biasing, and the "static" idle current vs voltage results were quite close to those of a 6B4G or 2A3 ((I don't have any 6A5s to compare. This was a "static" test only and not a complete working amplifier so I cannot comment on sound quality.
(I thought that I had posted those results on this forum, but I can't find them, so maybe I forgot to Yellow_Light_Colorz_PDT_09 Yellow_Light_Colorz_PDT_02
(Apparently there is at least one tube vendor who sells re-based and triode-strapped 6AV5GAs as 6B4G equivalents).
These 6AV5GAs should work in the G*S*G cirucit, keep everything original 6AX5 tube rectiifier, (no SS diodes, please) and the RK for each can be either 1000 or 900 ohms, though I'd probaly err on the side of caution, initially, and use 1000 ohms. This can be later decreased to 900 ohms by paralleling 9.1K to 10K if desired). Even 1100-1200 ohms mightr be better, TBD... (see Shannon's reply)
I sent Shannon a MQ of "NIMB" (New In Moldy Boxes) Tung-Sol 6AV5GAs for future experimentation, a while ago, and he sent me a couple of GSG boards - one of which is now in a fully functioning and nice sounding 6B4G amp!
/ed B in NH
Last edited by
EWBrown on Tue Dec 04, 2007 7:04 am, edited 1 time in total.
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