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A tubless tube amp

moray james

moray james

Super Member
anybody interested in a fully balanced amp with no global feedback ultr low noise design with no capacitors in the signal path and a super simple layout might want to take a very close look at Susan Parker's new Zeus amplifier built with just a hand full of parts. Best regards Moray James.

http://www.audiophonics.com/
 
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wow, talk about retro design. Phase splitter interstage transformers and output coupling transformers. Welcome to 1928. Now if only it actually had some tubes in there :) Those circuit designs would be right at home with some early direct heat triodes though. 71A outputs and a 26 driver or something along those lines. Heck, you could probably get away with a set of 01A's in there.
 
gadget73 said:
wow, talk about retro design. Phase splitter interstage transformers and output coupling transformers. Welcome to 1928. Now if only it actually had some tubes in there :) Those circuit designs would be right at home with some early direct heat triodes though. 71A outputs and a 26 driver or something along those lines. Heck, you could probably get away with a set of 01A's in there.
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Funny you say that, I've always wondered about a 71A / 26 amp.
 
Some of those old amps sound pretty good; the catch is they were not designed for 20hz-20khz, more like 70-10Khz because that's what recordings had back then. The devil is in the details. Good interstage, or opt, transformers that can do 20-20k +/- 1db are not cheap!
 
Calling it Zeus may be overstating the case a bit. I can't believe how basic it is.
 
goldleaf said:
That would be an interesting design. Guess the power transformer doesn't count?
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No power TX, a good enclosure instead with a voltage tripler. I'm already on that path, as my next custom build will be PT-less, but will have conventional OPTs.
 
gadget73 said:
wow, talk about retro design. Phase splitter interstage transformers and output coupling transformers. Welcome to 1928.
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Or the early 60's. Transistor radios used interstage transformers and push pull circuits. Though not HiFi!
6trdia.jpg
 
battradio said:
I personaly think good transformers sound better than good capacitors .
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Its just a lot more expensive and space consuming to make a good transformer than a good capacitor. I'd love to see and hear a proper effort though. It would be something to behold I think.
 
goldleaf said:
Some of those old amps sound pretty good; the catch is they were not designed for 20hz-20khz, more like 70-10Khz because that's what recordings had back then. The devil is in the details. Good interstage, or opt, transformers that can do 20-20k +/- 1db are not cheap!
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And those Sowter transformers she's using are definitely not cheap.
 
Over 200KHz bandwidth with a no feedback!

goldleaf said:
Some of those old amps sound pretty good; the catch is they were not designed for 20hz-20khz, more like 70-10Khz because that's what recordings had back then. The devil is in the details. Good interstage, or opt, transformers that can do 20-20k +/- 1db are not cheap!
Click to expand...

If you take a look at this very clever design you will see that it has no global feedback yet is still capable of 200 KHz band width. Yes you pay for the iron but in any good amp you pay comes down to what you are paying for. There is no free lunch. Best regards Moray James.

You might be impressed by some of those interested in Susan's amplifier design in this very in depth thread at DIY Audio. I was.

http://www.diyaudio.com/forums/solid-state/42259-zero-feedback-impedance-amplifiers.html
 
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gadget73 said:
Its just a lot more expensive and space consuming to make a good transformer than a good capacitor. I'd love to see and hear a proper effort though. It would be something to behold I think.
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IIRC Michael Fremer really liked the amp he heard that used all interstage transformers instead of capacitors.
 
jaymanaa said:
Susan, nice write up on the "Razor" in Wiki. I take it it's a female's page.
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Following the Wiki link (Occam's Razor), I came across my favorite Albert Einstein quote there:

"It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience"

Or, as it has been attributed to (but not absolutely verified to have been said by) Einstein- "Everything should be kept as simple as possible, but no simpler".

Regards,
Gordon.
 
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