The AC loading on the 300B thru the 5K:10K xfmr would provide some active hum cancellation of the power supply, but the DC loading of the power supply by the idle current of the 300B would make the hum worse. Pulling out the 300B probably does nothing much, except extinguish a glowing heater. Like recent political events, no harm done except draining someones wallet.
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I didn't think he was selling anything anymore, I thought he has passed away - could be wrong ? - but I do like his style - because he had some style, it was not a 'dry engineering' approach. There's room in the world for both approaches and this hobby is all the more enjoyable for it.
I believe he is still among the living. You may have him confused with Nobu Shishido, another eccentric Japanese audio designer.
John
John
I think this describes the Sakuma phenomena quite well: http://www10.big.or.jp/~dh/sakuma/
A number of my friends have made the visit to the restaurant Concord and describe Sakuma as a very gracious host.
He has written extensively in MJ and elsewhere about his passion for audio, and has made his designs freely available for fellow enthusiasts to experiment with.
His ideas are unconventional, and not without controversy particularly here in the West, not sure most Japanese diy'ers are all that concerned about the fringe element in their hobby. (Or if they even regard it as such)
A number of my friends have made the visit to the restaurant Concord and describe Sakuma as a very gracious host.
He has written extensively in MJ and elsewhere about his passion for audio, and has made his designs freely available for fellow enthusiasts to experiment with.
His ideas are unconventional, and not without controversy particularly here in the West, not sure most Japanese diy'ers are all that concerned about the fringe element in their hobby. (Or if they even regard it as such)
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I have never listened to devices built by using its schematics, but I support some of his ideas and the best thing I like is his unconventional, uncommon way of designing.
Purposefully putting a 300 ohm load on the input of the amplifier, and then still having to drive the grid of a power triode *facepalm*
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I bet if Sakuma cooks the way he designs his amplifiers, his restaurant would have been out of business a long time ago or shut down by the health department.
I find this morning Sakuma San schematics from legendary french magazine " L'Audiophile "
source nr 28/94 directed by master Jean Hiraga.
source nr 28/94 directed by master Jean Hiraga.
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No bleeder tubes but other Sakuma San schematic hope Thomas Mayer and Diyers find them interesting.
Best regards 🙂
Best regards 🙂
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Stumbled on this thread from 10 years ago! I have the MJ articles that might give an insight into these particular circuits.
In the 2009-2010 Sakuma is very much occupied with making a phono pre-amp, or EQ amp as he calls them, with the 841 tube. In that year he will make about 4 different designs with this tube.
Article 1 starts with him rediscovering 3 globe 841 tubes that were given to him by the owner of Sun Audio 30 years earlier. He is adamant that he can make them work as an output tube and starts off with using them in a sort of push-pull scheme.
He quite likes the result, but at louder volumes there is too much distortion.
So he redesigns the amp (after building several other power amps using the 841 as driver) and comes up with several SE versions of the phono pre and this time he wants to use them at a lower plate voltage. And to get there, he comes up with this bleeder circuit, that Sakuma also describes himself as 'heresy'. And also because he found a single WE300B somewhere in a cupboard and wanted to use it in this amp.
Lower plate voltage leads to better sound in his ears and he decides to keep the bleeder circuit and as an epilogue there is even a 'bet' between him and the editor of MJ magazine about the difference in sound it would or would not make when swapping the WE out for a chinese or russian 300B. The editor is certain it will, Sakuma has his doubts. After swapping the WE with a Chinese 300B, the sound of the amp changes and this confirms for Sakuma-san that the bleeder circuit is a worthwhile addition.
The input transformer in the 50 bleeder circuit, is because he doesn't want to put a resistor in front of the grid, so he puts a transformer there...
All in all he saw the 841 designs as a great adventure for him as a designer and wanted to see how far into the unknown he could go!
If anyone is interested in the full story, I can see if I can scan the pages and you can google translate
In the 2009-2010 Sakuma is very much occupied with making a phono pre-amp, or EQ amp as he calls them, with the 841 tube. In that year he will make about 4 different designs with this tube.
Article 1 starts with him rediscovering 3 globe 841 tubes that were given to him by the owner of Sun Audio 30 years earlier. He is adamant that he can make them work as an output tube and starts off with using them in a sort of push-pull scheme.
He quite likes the result, but at louder volumes there is too much distortion.
So he redesigns the amp (after building several other power amps using the 841 as driver) and comes up with several SE versions of the phono pre and this time he wants to use them at a lower plate voltage. And to get there, he comes up with this bleeder circuit, that Sakuma also describes himself as 'heresy'. And also because he found a single WE300B somewhere in a cupboard and wanted to use it in this amp.
Lower plate voltage leads to better sound in his ears and he decides to keep the bleeder circuit and as an epilogue there is even a 'bet' between him and the editor of MJ magazine about the difference in sound it would or would not make when swapping the WE out for a chinese or russian 300B. The editor is certain it will, Sakuma has his doubts. After swapping the WE with a Chinese 300B, the sound of the amp changes and this confirms for Sakuma-san that the bleeder circuit is a worthwhile addition.
The input transformer in the 50 bleeder circuit, is because he doesn't want to put a resistor in front of the grid, so he puts a transformer there...
All in all he saw the 841 designs as a great adventure for him as a designer and wanted to see how far into the unknown he could go!
If anyone is interested in the full story, I can see if I can scan the pages and you can google translate
A bleeder tube may act like a constant current source, so loading would not change with voltage variations in what it is loading. Is that a necessary condition, dunno. I-source imposes a high impedance load compared to a resistive one. In some settings, that could be helpful.
