Posted by SteveBrown [ 68.0.84.71 ] on December 16, 2007 at 08:12:56:
In Reply to: Ping Steve Brown -- re: Seth(s) posted by Skip Pack on November 28, 2007 at 20:02:53:
Skip, sorry I didn't see your note sooner! Yes, I've built a "SETH" style amp, got one sitting on my floor right now (though fitted with 6L6's not 2A3s). If you're going to use 2A3's, you only need to swing +/- 70v or so at the driver, so no need to give it a 460v supply. I don't know what driver tube you will use, but if you stay with something that has high transconductance like the design calls for, at say 150v on the plate, you don't need more than a 300v supply for sure - in fact, that would even run a 300b pretty well (Gordon from Wavelength Audio has advocated this for using a WE417a for 300Bs and I've built it that way, works great). As for the 6B4G's, I didn't have good luck with hum on them. This is related to the higher heater voltage and not using DC on the fils. I'd recommend staying at 5v or less (that is, use a 2A3 or 300B). The Sovtek single plate 2A3 is a very nice tube, and not all that expensive. By the way, I had MQ do my EXo-173's w/some nickle lams and I really like the way it sounds. Not sure what the standard sounds like. Best of luck!
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