I know I saw these things and I was wondering if anyone knew where from, or had them. They are audio output circuits that are unusual.

One is an output transformerless amp with multiple triodes in parallel. It's obvious why they should be triodes as well as needing many sets. What I remember about it was the splitter stage. It used a triode seemingly like a normal splitter stage in a push pull tube amp, but there was a bootstrap cap involved. A buddy o mine is thinking of building such an amp and I wanted to have another look at it. I thought I had it on the PC but I looked for weeks and it is gone.

I am chiefly concerned with the splitter stage because errors there just........ **** the whole deal up. I THINK maybe the sum of the two plate resistors equalled the cathode resistor and the bootstrap was applied to the junction. Either that or all three resistors were the same value.

My problem I see is that the triode has to have a pretty flat plate current curve for this to work well. ANY tweaking with resistor values throws it off in ways you do not want since it is to feed a speaker. It would also be interesting to know what triode they used, because of that. If the curve isn't flat enough it'll cause the outputs to work against each other. Well, if ya want class A...... but I do not want it by accident.

Instead of direct coupling we are thinking of feeding a transformer. I know how stupid that is, but this is an audiophile thing. Spare time and spare money.

The other circuit I would like to find, believe me I could just figure the thing out but I just don't want to because it is a novelty as far as I am concerned, is a stereo amp kinda made out of a mono amp. Kinda.

One output transformer's secondary tap was used and the other was not, same with the primaries. I believe it had three output devices. The L+R mono was sent to the push pull output stage, where through the wiring of the secondaries fed both speakers in phase. The L-R difference signal was in series somehow with this via the primaries windings. It was like FM multiplex. It's as if the engineer wanted to make the mono sound the priority and the stereo "compatibility" a secondary issue when it came to sound quality. He probably also reasoned that very little material came exclusively out of one side of the system and that the bass was always present in both channels. Of course there was a hell of alot of mono material out there at the time. I make it early 1960s, but that is just a guess.

Really, I can understand, he was making it stereo but at the minimum cost. Doing his job.

Just a little something for when you get tired of dealing with life. Explore the stupidest circuits possible. But then some people can't get enough of the sound.

Yeah.

In article ,
wrote:

I know I saw these things and I was wondering if anyone knew where from, or
had them. They are audio output circuits that are unusual.

One is an output transformerless amp with multiple triodes in parallel.

Google on "Futterman".

Isaac