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In Reply to: RE: 6AQ5 PP amps posted by danlaudionut on April 08, 2014 at 22:45:34
Not my home page. The "El Cheapo" project started on the Audiophile Talk site, which was hosted by Steve Deckert. Unfortunately, the site was "hacked", totally corrupted, and taken down.
For the "umpteenth" time, I'm uploading the schematic graphic.
Eli D.
Follow Ups:
Thanks so much Eli ! We appreciate your efforts on behalf of the community.
May I make a small suggestion/request? If you have the recommended voltage values for B+, B2+, and B- perhaps you could consider adding them to the drawing. If I recall from a couple years ago those values used to be covered in the thread, but of course no longer. Those who may be considering a build with different iron will need to know.
Gary
The needs of the 12AT7 small signal circuitry rule the roost. The 'T7 triode sounds GOOD with 200 to 225 V. on the plate and an I B of 3 mA. A B+ rail of 355 V. takes care of "everything", if you keep "check valve" decoupling. The drop in the decoupling network shown is under 2 V.
The B- rail voltage is pretty flexible. It has to be "tall" enough to power the CCS and provide "compliance" with the drive signal. The B- setup shown on the graphic is very economical, along with starting "softly", which keeps the 'T7 grids from becoming positive relative to the cathodes. Builders in "240" VAC power zones will have to work out another B- supply scheme.
Eli D.
Thank you for all the input. I never considered triode and I was thinking a three stage amp would be better .... which by consensus seems to be unnecessary and at worst a step back in sound quality.
A special thanks for the schematic.
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