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In Reply to: Re: Curious why the O.T.L. board moves so much slower than the S.E.T. board. posted by Tom Dawson on June 28, 2005 at 12:36:42:
There you go. I guess we will have to imagine your circuit. I certainly did not mean to imply that there are no viable alternatives to the Futterman and circlotron. Do you plan to market amplifiers using your novel topology?While we are at it, can anyone exposit on the Joule and Graaf circuit topologies? I really know very little about either of those two. I have been guessing that Joule uses a mu-follower to drive a circlotron, but it's just a guess.
Follow Ups:
You are basically correct about the Joule OTL's topology. The details in the exceution of the design are of course a more complex and what makes the Joule amps what they are. Having had a tutorial by Jud Barber on the design of his amps, while not rocket science, I certainly understand that he preferes to keep certain implimentation/excecution details of his OTLs to himself.
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
Ah, sweet mystery of life....I really don't think that a general verbal description of the circuit would compromise the market for Joule, but it certainly is his (Jud Barber's) decision to make.
Maybe I'm too close and familiar with the Joule OTL's, but I would think that just looking at the tube compliment and knowing its single eneded input, circletron amp would tell a fair amount about the basic circuit, would it not????Jud is not much of a internet guy, being the old skool gentleman that he is :-) , so you will not be seeing him posting on internet forums to discuss things such as this but I have seen him talk with interested folks at shows about various design aspects of his amps.
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
And his affection for the mu-follower is not a secret either. I wonder whether the amps use NFB at the output and if so how it is implemented.
There is variable feedback at the output... [ knob on top of the amp - upper right corner of the picture shown in this post :-) ]. Feedback is local I believe.
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
And I suppose the power transformer(s) are toroidal; the flat disc shape would be hide-able inside that massive chassis, under the circuitry.
Yes, multiple transformers per monoblock... at least (big) one is torridial... plus there is the variac, then I think one other smaller transfromer (which I can't recall if its torridial or not) plus another little transformer for the digital meter power supply.Compared to what you find in most (tranformer output) tube amplifiers, the power supply design is a good deal more complex! :-)
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
I suppose I ought to make a try at marketing this OTL topology, but I somehow have never got around to it - too many competing projects and things to do, I suppose, and I've been more of a lab rat being an all purpose circuit board and system level analog & digital designer & programmer by day.Graaf had come out with at least one 'DC coupled' OTL, but from the schematic I saw it would have a very high DC potential at its output, requiring a return at the same elevated potential or a DC blocking output capacitor the latter of which would disqualify it from really being fully 'dc coupled' in my book.
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