Posted by Damir [ 213.202.69.133 ] on February 05, 2005 at 13:02:06:
In Reply to: Juvenile request posted by Wayne Parham on February 04, 2005 at 18:30:19:
SE 2A3 (6B4G, 6A3) power amp would be rel. easy, IMO - with typical OP (Uak=250V, Ugk=-45V, Ia=60mA, Ra=2k5, Pout=3,5W), we need about 32Vrms "input" from the driver for the full power. With our high-output "Guinevere" line stage, we can comfortably use one - tube driver with active load, say again 5687, or ECC99, E182CC, or something from 6SN7 "family", say 6J5GT single triode.
PS would be little more complicated, say LCLC for B+ of about 300V, motor-run caps again. For the input tube/driver additional LC (or RC stage). With active (DN2540 again) load, about 300V or little less is enough B+ for the above tubes. I can draw the schematic, even breadbord the prototipe, I`m sure that Doug can give some ideas, especially with Hg-rectifiers (I don`t have the experience with those).
All in all, IMO - project easy enough to build, but "good enough" (with good transformers - "Heyboer" again, or...?).
PP 2A3 is another option, maybe better - but little more complicated, especially phase splitter/driver - it`s hard to do it "right" simple. Probably larger/separated B+ for the driver is in the order (400V or so, even larger), and probably 2-stage is requied.
Just some thoughts, we`ll see... 
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