Whilst googling Japanese hi-fi, as insomniac audiophile types sometimes do,
I stumbled on what appears to be quite an interesting design for a valve power amplifier.
Not being versed in the fine art of valve circuit design, I thought some of the experts might weigh in,
if they're similarly sleep-deprived and looking for something to pass the time in the wee hours of the morning.
Shoichi Yoshimoto is quite forthcoming about his Model 7 Amplifier design, which helps I imagine.
It's a "Single stage Cascoded differential amplification circuit",
some kind of MOSFET/Valve auto-biasing hybrid that works with EL34, KT66, 6L6GC, KT77, KT88, 6550, and 350B valves.
General Info:
(http://softone.a.la9.jp/english/Model7/M7-eng-1.htm)
Circuit Info:
(http://softone.a.la9.jp/english/Model7/M7-eng-3.htm)
On the Japanese page there's even a link to an .emf file - which I can't open since I'm on a Mac. Guessing this is a high-res version?
(http://softone.a.la9.jp/Model7/M7-2.htm)
P.S. I'm not specifically looking to purchase this item, so not asking for advice in that sense. Just curious about the design. Good vs. bad. Pros vs. cons. It happens to be priced fairly low for a made-in-Japan product ($750) - which indeed it is (made in Japan), as Shoichi-san confimed to me via email. I think his overall approach is to use fairly standard, non-boutique parts, and the R-Core transformers* used are all made in-house.
* (http://softone.a.la9.jp/english/RX30-8/RX-30-8.htm)
I stumbled on what appears to be quite an interesting design for a valve power amplifier.
Not being versed in the fine art of valve circuit design, I thought some of the experts might weigh in,
if they're similarly sleep-deprived and looking for something to pass the time in the wee hours of the morning.
Shoichi Yoshimoto is quite forthcoming about his Model 7 Amplifier design, which helps I imagine.
It's a "Single stage Cascoded differential amplification circuit",
some kind of MOSFET/Valve auto-biasing hybrid that works with EL34, KT66, 6L6GC, KT77, KT88, 6550, and 350B valves.
General Info:
(http://softone.a.la9.jp/english/Model7/M7-eng-1.htm)
Circuit Info:
(http://softone.a.la9.jp/english/Model7/M7-eng-3.htm)
On the Japanese page there's even a link to an .emf file - which I can't open since I'm on a Mac. Guessing this is a high-res version?
(http://softone.a.la9.jp/Model7/M7-2.htm)
P.S. I'm not specifically looking to purchase this item, so not asking for advice in that sense. Just curious about the design. Good vs. bad. Pros vs. cons. It happens to be priced fairly low for a made-in-Japan product ($750) - which indeed it is (made in Japan), as Shoichi-san confimed to me via email. I think his overall approach is to use fairly standard, non-boutique parts, and the R-Core transformers* used are all made in-house.
* (http://softone.a.la9.jp/english/RX30-8/RX-30-8.htm)
