Yes, but these also were 1950ies designs - as I said before .
Best regards!
Kello Kay Pirinha, Sorento and all.
Each one of you has a great memory; truly admirable!
The US patents for Circlotrons by the independent inventors Wiggins [1958 grant] and Hall [1955 grant] are attached [c/o uspto.gov]. The Wiggins patent shows the use of Positive Current Feedback [PCF] as articulated by Kay Pirinha. The Model A50 Amplifier by Electro-Voice, Inc. is its reduction to commercial practice.
Hall and Wiggins, most probably were the only producers of their Circlotron power amps during the 1950ies; because of IP protection by US Patent Law.
Best wishes
Anton
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Schematics updates HOME Thanks to Japanese DIY Friends
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To pics 2 and 3 in this posting: Most probably never will I understand what might have driven the designer to put two output tubes in parallel instead of designing PP, just in case he has two tubes ready ? Most probably he must have known that TV sweep tubes are rather benign in PP, but somewhat delicate in SE .
Best regards!
Most probably never will I understand what might have driven the designer to put two output tubes in parallel instead of designing PP
Тhe desire to create an amplifier with a specific SE sound character. What else is there to understand?
A pretty impressive solution with no signal coupling caps.
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Hi, there is a 6EM7 PP in post #403. Seems a nice one to try. I wonder if the OPT is a 5K/8 Ohm ? ..
https://tango-trans.com/wordp/wp-content/uploads/catalog/FX-40-5.pdf
Push-pull output transformer | Output transformer | tango-trans
Ok, now I understand: An effects machine!!
Best regards!
Every amplifier is an effects machine in the sense that it has an obvious audible signature.
Some produce rather unpleasant effects.
Some even have the "signature" of transparencyEvery amplifier is an effects machine in the sense that it has an obvious audible signature.
It is just slightly humorous to think that two valves in parallel make an effects machine but the same two in series miraculously turn "high fidelity reproduction".
I know, right? And people don't look at their preamps, which are mostly single ended. So what if it's an effects machine? I like it.
Due to dynamic driver induced distortion (.2 - 2% typical), fidelity at voltage of amp output does not correlate linearly with acoustic distortion. From your POV, I assume that you have never compared measured acoustic fidelity of PP to SE.The obvious difference is SE vs. PP.
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