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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
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Old 14th November 2017, 08:04 PM   #21
Zen Mod is online now Zen Mod  Serbia
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
nope, I didn't

it's there just in case ...... from same reasons Pa is placing them at GS mosfet junction , from Dark Age

I put there first thing from drawer , bigger than 4V .......... I believe I used 6V8
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Old 14th November 2017, 08:43 PM   #22
Antoinel is offline Antoinel  United States
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
Current flowing through the Zener Z1 is expected have a low value; maybe in the uA range; so as to generate the joint [ -Vgs] to DEFiSIT or DEF. This Zener current flows from the output through the autoformer and terminates at the joint sources of the input buffer JFETs. Too high a Zener current may "magnetize' the autoformer and cause sonic heartburn as I recall from the work of lhquam on diyF6. Maybe the Cinemag autoformer does not care about this potential problem of DC continually flowing through it!.
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Old 14th November 2017, 08:56 PM   #23
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
well , I understand it as I wrote , zener being limiting device , to not exceeding GS voltage , for both parts in same time

is this time for another e-mail to Papa , to ask him ?

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Old 14th November 2017, 09:11 PM   #24
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
Did you finally get something to replace your favorite M2? ;-)
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Old 14th November 2017, 09:32 PM   #25
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
more than enough candidates ........ but none of them really counter-candidates , each having own flavor and virtues

Babelfish J , Babelfish J2 , M2 .... name it ...... I can't really pick ;

list of amps in which I wasn't so personally interested is even longer



catch is - my speakers are pretty benign , regarding drive , so I can enjoy amps with finesse even if price (for finesse) is having them in corner reserved for wimpier ones

anyway , M2 and DEFiSIT - close cousins , M2 being more all-rounder (50W/4R is decent , if you ask me)

almost forgot ..... I'll see (hear) hopefully soon what's going on with Babelfish XA25

edit: of course that each one - classified as Papa's Koan , is personal gift ...... be it complete (real , physical) amplifier , or "just" files ..... is absolutely priceless and incomparable

Joie de vivre

further explanation of phenomenon absolutely redundant
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Last edited by Zen Mod; 14th November 2017 at 09:39 PM.
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Old 14th November 2017, 09:37 PM   #26
Antoinel is offline Antoinel  United States
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
Quote:
Originally Posted by Zen Mod View Post
well , I understand it as I wrote , zener being limiting device , to not exceeding GS voltage , for both parts in same time

is this time for another e-mail to Papa , to ask him ?

Most interesting and creative solution to generate -Vgs to bias DEF and/or DEFiSIT. What I also find technically astounding for DEFiSIT is that a triode-like and a pentode-like devices are working together[cleanly] in push-pull mode. The electrical characteristics of a SIT and a P-MOSFET are very different!

I hope that Mr. Pass will in due time explain the Zener circuit to generate -Vgs, and other charms of DEF and DEFiSIT.

Best
Anton
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Old 14th November 2017, 09:48 PM   #27
Nelson Pass is offline Nelson Pass  United States
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
Z1 is simply protection. With xfrmr for gain stage is possible to come up
with enough voltage to break Jfet or Mosfet. It will not be conducting in
normal use.

Z2, Z3 and Led are just to make a voltage to use for offset adjust. I have
lots of 9.1 zeners in boxes, so I set it up for multiples of 9.1. However, power
supply was too low to bias 3 of them (27.3V plus) and 18.2 was too low
for operation, so I used a Led to put me in between.

If I were to lay this circuit out again, I would put adjustable TL431 in their
place....
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Old 14th November 2017, 09:49 PM   #28
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
entire biasing current , demanded by output's gates , including AC modus demands , is delivered through xformer winding ;

currents are minuscule in DC realm , little bigger when swing rises , but nothing to write home about

consider that those xformers aren't small piglets made for MC signal , but classic PA jobbies , made to withstand serious abuse

their job in M2 and DEFiSIT is trivial , regarding seriousness of loading

so , diode isn't wodoo part here ; omit it and everything will work the same , as long nasty spikes are far from gates

edit : he's faster ,again ........ typed in same time
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Old 14th November 2017, 09:51 PM   #29
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ZM > anyway , M2 and DEFiSIT - close cousins ..

Similar and different beacause Pass SIT-1 and Cinemag etc.
M2 without input and output capacitors.
Curious about Your first music play with DEFiSIT
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Old 14th November 2017, 09:51 PM   #30
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
Quote:
Originally Posted by Nelson Pass View Post
......

If I were to lay this circuit out again, I would put adjustable TL431 in their
place....

naah .... too common and too simple

LED string ( 3mm greens and MMBF5486) is so much more fun

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