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RE: I have an idea...

"I think the reason that what you describe is never done with an OTC amplifier is probably because of the high voltages involved. The speaker wires would have to carry thousands of volts in most cases, which is both unsafe and unwise."

Yes, I agree that one would not wish to do that in practice, for the reasons you mention. But I was really just considering it as a thought-experiment, to make the point that it would not, in any case I think, change the interpretation of the setup as an OTC system.

Actually one thing one could do, which I don't think is often done, would be to make something like a totem-pole or circlotron OTL amplifier, but just with more common or garden tubes like EL34 or whatever, and then use something more like an ordinary output transformer to match the relatively high output impedance of the amplifier to that of the loudspeaker. Then, the primary of the OPT would be at close to zero potential, and there hazards you mentioned would not arise, even if one did want to mount the transformer close to the loudspeaker. Also, for what it's worth, there would be no quiescent DC current passing through the transformer primary. Probably it would require higher HT voltages than is normal in an OTL, to get any decent power.

Of course I would not call the setup an OTL system, for the same reason that I would not call the system with Zero autotransformers OTL, but just thinking of it as a possible type of amplifier one could construct.

Your comment about driving ESL speakers puts me in mind of a crazy thought I once had, namely that one could envisage an OTL amplifier that would directly drive the ESL speakers without any step-up transformer at all. It would be a horrifically fearsome thing, I think, requiring something like a totem-pole or circlotron but with transmitter tubes and HT voltages being of order thousands of volts. Definitely not something I would want to make or have in the house!

Chris



Edits: 05/17/17 05/17/17

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  • RE: I have an idea... - cpotl 08:56:40 05/17/17 (0)

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