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From the plate curves for a triode connected 6V6 and the few comments I've seen on the asylum, it appears that a 6V6 may make a good class A common cathode voltage amplifier. Rp is low (1960 Ohms), and gain is reasonable (9.8). I'm thinking of a supply voltage of 430 volts, a plate load of 5000 Ohms, and a plate current of 36 mA. Has anyone tried this?The application is a voltage amplifier preceeding a Baxandal tone circuit (a loss of 20 dB). I like the 27 for this application, but am looking for a IDHT so as to avoid microphonics and a complicated filament supply.
Follow Ups:
but thought to be microphonic in some circuits.
So much for my memory. You are correct, the 27 is a IDHT and I have not tried one. I have tried the 26, and it's microphonic (at least the one that I have).
I am playing now with 26. Filament power does require extra work. Most folks perform this work in the form of DC arrangements, batttery or CLCLCLC filtering. I am using AC, but need separate supplies for each tube and have 2 tubes in each channel, so for stereo need four 1.5v at 1.05A supplies. I also need a hum pot on each tube. AC is a great way to go, but it is not as easy as AC on an IDHT.I have found microphonics of the 26 damped in a stacked Aikido-style arrangement. In other circuits I tried the same tubes were much more microphonic. In fairness, I am getting a gain of one-half mu, call it a net of 4, so that may explain where the microphony went.
You would get much more drive current out of your 6V6. I recall that the Chimera Labs Axiom amp used a triode-wired 6Y6 as a driver, and reportedly achieved very good linearity.
Thanks for the informative reply! So can you achieve acceptable hum levels with AC on the filaments? If so, I would prefer to go with AC.
I can achieve a respectable level of hum -- all but inaudible in my headphone amp. When I had only one channel built, it was inaudible, but with two channels there is a teeny bit, which I think may be induced somewhere in my spaghetti mess of wires.I wrote up my work on this a while back. A schematic appears here, thanks to helpful inmate Jose K:
http://db.audioasylum.com/cgi/m.mpl?forum=tubediy&n=112851&highlight=26+headphone&session=
click the connecting posts to that one and find more of my effusions on the topic.
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