Gold mine of DI¥ audio tubes schematics from Japan

[jjasniew]

I've never seen an A50 amplifier. Very informative link - thanks! Amazing the stuff they knew before I was born, like you may want to vary your amplifier's output impedance w.r.t. speaker placement in the room. Versus today's "zero for every situation" norm.

 

[Antoinel]

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

 

[Soundhappy]

Schematics updates HOME Thanks to Japanese DIY Friends

 

[Soundhappy]

Our Japan on Vimeo

 

[Soundhappy]

DIY articles HOME

 

[Kay Pirinha]

Our Japan on Vimeo

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!

 

[analog_sa]

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.

 

[Kay Pirinha]

Ok, now I understand: An effects machine!!


Best regards!

 

[indra1]

You got it, the effect of which potentially cancel some of the distortion generated by dynamic driver.

 

[Mosquito]

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 ? ..

 

[Soundhappy]

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

 

[Mosquito]

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[Mosquito]

👍👌

 

[analog_sa]

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.

 

[scottjoplin]

Every amplifier is an effects machine in the sense that it has an obvious audible signature.

Some even have the "signature" of transparency

 

[Kay Pirinha]

...and some the one of true, high fidelity reproduction...
Best regards!

 

[analog_sa]

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".

 

[Kay Pirinha]

The obvious difference is SE vs. PP.


Best regards!

 

[directdriver]

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.

 

[indra1]

The obvious difference is SE vs. PP.

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.