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..
Although you can use transformers for amplifying the voltage, since you can't get somegthibg for nothing, you still need current amplification..
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
- Klaus
damianl said:
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?
"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.
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.
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))))
An externally hosted image should be here but it was not working when we last tested it.
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))))
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/trans...ral-for.narod.ru/index/stones/first_stone.htm
- Klaus
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/trans...ral-for.narod.ru/index/stones/first_stone.htm
- Klaus
Re: Re: transformer amplification amplifier
Not really. Quite old stuff. Was the usual way of amplification before the invention of the triode. Lars Lundahl sold an amp called "Magamp" in the early nineties. What was new about it was the better efficiency. A simplified schematic was in an audio magazine at that time. I tried to find it again, but wasn´t successful. VAC builds magamps for stabilization of power supplies.
http://www.vacuumschmelze.com/dynam...ation/applicationknowhow/magamptechnology.php
PMA said:
Not really. Quite old stuff. Was the usual way of amplification before the invention of the triode. Lars Lundahl sold an amp called "Magamp" in the early nineties. What was new about it was the better efficiency. A simplified schematic was in an audio magazine at that time. I tried to find it again, but wasn´t successful. VAC builds magamps for stabilization of power supplies.
http://www.vacuumschmelze.com/dynam...ation/applicationknowhow/magamptechnology.php
Gordy said:
Do not turn on Gx attention. Make without them. This my now-khow ((( ))
My email vumfsl@gmail.com if council is required to you.
On magnetic amplifiers, see
"Electronic Transformers and Circuits", Reuben Lee, 1955, Chapter 9
availabe at
http://www.pmillett.com/tecnical_books_online.htm
(one of the best online resources. Thanks Pete!)
- Klaus
"Electronic Transformers and Circuits", Reuben Lee, 1955, Chapter 9
availabe at
http://www.pmillett.com/tecnical_books_online.htm
(one of the best online resources. Thanks Pete!)
- Klaus
Here is an other text about magamps:
http://www.butlerwinding.com/elelectronic-transformer/mag-amp.html
http://www.butlerwinding.com/elelectronic-transformer/mag-amp.html
no bad idea !
this is no bad idea !
Amplifiing stage without any semiconductor or tube distortion
try JFET stage(Au=1) , good transformer , and MOSFET A-class stage (Au=1) , no capacitor :O)
I try old transformer from 8:1 100V "wire" radio distribution (in Slowakai 30 years backward :O) and sound is very fast and impressive...
Kuznec
this is no bad idea !
Amplifiing stage without any semiconductor or tube distortion
try JFET stage(Au=1) , good transformer , and MOSFET A-class stage (Au=1) , no capacitor :O)
I try old transformer from 8:1 100V "wire" radio distribution (in Slowakai 30 years backward :O) and sound is very fast and impressive...
Kuznec
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