A2 experiments.

We all start somewhere
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#106 Shishido

Post by IslandPink »

Mike H wrote:I'll take your word for it. :D
Ok, I shall shift into teacher mode :D :
http://www.wavac-audio.jp/poweramp_e.shtml
http://www.wavac-audio.jp/sh833_e.shtml
"Clear and full bass sound can be reproduced by IITC (Inverted Interstate Transformer Coupling) circuit."
"Enjoy the carefree satisfaction of living with the best. HE-833"
( and of being in debt for the rest of your life ! )

"When I considered my concepts, I went back to the starting point of analog sound as vacuum tubes. At the same time, I had a fateful meeting with late Mr. Shishido who designed a new tube circuit. We developed new products by trial and error, but we were blessed with wonderful chassis design and staffs.
Another blessing was we had many audiophiles all over the world who agreed with our concepts."

Very nice resource of his circuits and explanation -
http://lagarto-ex-infoseek.jp/shishido/ ... -skema.htm
eg.
http://lagarto-ex-infoseek.jp/shishido/838se.png
"Once you find out ... the Circumstances ; then you can go out"
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#107 Mr. Michimori

Post by IslandPink »

Ooh, now I've found something else really nice, I've set myself off here :

http://www6.plala.or.jp/Michi/index.html
100TH amp here - nice !
http://www6.plala.or.jp/Michi/renewal10 ... 20Amp.html

http://www6.plala.or.jp/Michi/ETF%20200 ... ation.html
"Once you find out ... the Circumstances ; then you can go out"
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#108

Post by Mike H »

Oh right I see. I think :D
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#109

Post by IslandPink »

My suspicion is that you can only hope to reduce the amount of DC magnetisation in the core, because the amount of A2 (grid) current is unlikely to match the amount of current in a typical (hefty) driver valve for these big triodes, which might be 30-40mA . Even a reduction in the amount of gapping required would help quite a bit on inductance though .
"Once you find out ... the Circumstances ; then you can go out"
User avatar
Nick
Site Admin
Posts: 15709
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#110

Post by Nick »

That is the plus of cathode drive, the current is constant, so it is possible to balance it if you want.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#111

Post by Mike H »

IslandPink wrote:My suspicion is that you can only hope to reduce the amount of DC magnetisation in the core, because the amount of A2 (grid) current is unlikely to match the amount of current in a typical (hefty) driver valve for these big triodes, which might be 30-40mA .
Same here, still better than nuffink though? :D

I don't think he pretends it will be cancelled completely.

Even a reduction in the amount of gapping required would help quite a bit on inductance though .
By my own experiments it's not that simple, there's a threshold where make it too small and bonk, it's all gone, suddenly reverted to gapless.

Just BTW recently I was doing some experiments with a large gapless p-p transformer to find out how much DC it would tolerate, only 10.5mA dropped it from 180H to 90H!


I am quite taken with Shishido's 801A A2 schematic, I think this could be do-able with what I've got.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Paul Barker
Social Sevices have been notified
Posts: 8874
Joined: Mon May 21, 2007 9:42 pm

#112

Post by Paul Barker »

Mike H wrote: I was doing some experiments with a large gapless p-p transformer to find out how much DC it would tolerate, only 10.5mA dropped it from 180H to 90H!.
corroberated. Interleaved cores are no use at all for any amount of DC.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
Post Reply