transformer amplification amplifier

[damianl]

I thought i saw an amplifier here somewhere that uses a transformer for amplification rather than transistors. Am i correct? If so could i have links please.

Thanks
Damian

[dhaen]

Do you mean this one Zero Feedback Impedance Amplifier ?
Although you can use transformers for amplifying the voltage, since you can't get somegthibg for nothing, you still need current amplification..

[KSTR]

Take any decent self-contained, unity gain output stage with a high impedance input and (typically) high localized feedback, and hook a Lundahl LL7905, driven this way. That's it, no simpler VAS available. Simple and elegant, low noise, galvanic isolation, EMI-proof, though a bit costly (the xformer).

- Klaus

[damianl]

SO what i am looking for is an amplifier incorporating an audio output transformer rather than transistors? i am interested in building like this and how they sound.

[wg_ski]

Originally posted by damianl
SO what i am looking for is an amplifier incorporating an audio output transformer rather than transistors? i am interested in building like this and how they sound.

I will still have transistors - just less of them. You can do a good job with just *two*. How will it sound? Probably a lot like a push pull pentode tube amp.

I've got an idea - if you use both input and output coupling transformers couldn't you just do away with the power transformer? 500 volt hexfets are cheaper than a power transformer, aren't they?

[djk]

"I've got an idea - if you use both input and output coupling transformers couldn't you just do away with the power transformer? 500 volt hexfets are cheaper than a power transformer, aren't they?"

The output transformer to go less than 60hz will be bigger than a 60hz power transformer, and much harder to design for the broad bandwidth required for an output transformer.

[PMA]

Originally posted by damianl
I thought i saw an amplifier here somewhere that uses a transformer for amplification rather than transistors. Am i correct? If so could i have links please.

Thanks
Damian

If it amplified a POWER, it would actually be a candidate for a Nobel prize.

[Vlauga]

I have thought up the amplifier with the passive transformer amplifier of voltage already about fifteen years ago. Several years ago published it scheme at this forum, but nobody has paid attention)))



My amplifier since then have repeated many people. Which consider, that my amplifier sounds definitely better, than the best tube amplifiers on greater tubes like WE211.

The description how to do the amplifier is to the address of. In the end article also it is told, how most to make for it the transformer, the power supply and the device of a delay of connection of loudspeakers.


Calculation of the step-up transformer for the First stone ©Ul'yanov

The article (In Russian)))


P.S.I know, that I the genius))) And not because of this amplifier)) Because I know, whence we, people, and what for))))

[KSTR]

I'm with you, Vlauga, I'm with you, because your schematic exactly realizes what I have proposed in post #3, in a very simple and elegant way. There are not many VAS stages easier and better than a good transformer.

Clever schematic, I like the (passively) boostrapped diamond buffer. The input "grid" choke is also very rarely seen in solid state designs, although it has many advantages.

Probably it didn't gather much attention here because of two things:
1) most solid state designers are somehow afraid of iron in the signal path,
2) it will not qualify as a "low distortion amplifier" when tested with textbook measurements.

For those interrested I babelfished the article web site:
http://72.30.186.56/babelfish/transl...irst_stone.htm

- Klaus

[Gordy]

Originally posted by Vlauga
I have thought up the amplifier with the passive transformer amplifier of voltage already

Vlauga, I saw your amplifier some time ago and thought that it looked very interesting. It is on my list of things to try "when I get the time".

By the way, what are G11 to G14?