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Old 6th April 2005, 09:24 PM   #11
acaudio is offline acaudio  Germany
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Quote:
That's even more cruel that saying nothing

be patient



I had an idea and drawn this circuit. It is based a little on answers and publications from Mr.Pass and publications from Mr.Borbely in Audio Electronics (The new frontiers-> Basis knowledge to JFETs) .
I mailed this to Mr.Pass with ask for publishing-permission (Thank you Mr.Pass).
He answered Passlabs use only a single set of secondary mosfets, so I have simplified this. External components are not drawn. Actually schematic coming soon. (I play at present a little with the values)

Please excuse my very poor english.

Best wishes
Adam
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Old 6th April 2005, 09:38 PM   #12
Bricolo is offline Bricolo  France
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Did you draw the schematic this way in order to explicitely show an "X"?


PS: your english is ganz gut
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Old 6th April 2005, 09:45 PM   #13
acaudio is offline acaudio  Germany
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Quote:
Originally posted by Bricolo
Did you draw the schematic this way in order to explicitely show an "X"?

I like "X"

In the figure of feedback (next update) is this so simply to draw.

/Adam
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Old 6th April 2005, 09:46 PM   #14
zinsula is offline zinsula  Switzerland
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Default Interesting...

...as I also had Pass (Zen V5 for the second stage and the Susy patent for input) and some Borbely articles in mind for this....

NB-Don't rely on the values, and I think that some compensation caps would be needed. It's just the topology I want to show...don't know if it will work, still buying (=looking for ) the components...

Later, Tino
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Old 6th April 2005, 09:53 PM   #15
zinsula is offline zinsula  Switzerland
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Default As I saw Acaudio's Board.....

.....I thought this would be the natural evolution of the circuit above

But now you overtook me in posting the schematic, and yours seems to be quite more refined...
Am I wrong or can I see some John Curl elements in the input stage?

Well, I attach my proposal of the balanced thing....

Ciao, Tino
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Old 6th April 2005, 10:02 PM   #16
acaudio is offline acaudio  Germany
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Default Re: Interesting...

Quote:
Originally posted by zinsula
...as I also had Pass (Zen V5 for the second stage and the Susy patent for input) and some Borbely articles in mind for this....

NB-Don't rely on the values, and I think that some compensation caps would be needed. It's just the topology I want to show...don't know if it will work, still buying (=looking for ) the components...

Later, Tino
It looks very similar,I think, it will work, my works already.

adam
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Old 6th April 2005, 10:08 PM   #17
gl is offline gl  United States
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Outstanding work gentlemen. Thank you for posting. This looks like it could turn into a great thread.

ACAUDIO: It looks like your schematic has twice as many MOSFETS as the PCB. Is this what you meant by "Passlabs use only a single set of secondary mosfets"?

GL
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Old 6th April 2005, 10:17 PM   #18
MRupp is offline MRupp  Germany
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Shouldn't the JFETs be cascoded - I thought I read this in a post from Nelson Pass (would also similar to the Borbely design) ?
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Old 6th April 2005, 10:24 PM   #19
zinsula is offline zinsula  Switzerland
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Quote:
Originally posted by gl
........This looks like it could turn into a great thread........
That would be great.
I was "dreaming" of stuffing the non balanced circuit on a very compact PCB without input and feedback resistors, just as an op amp replacement....

But this balanced thing is also quite interesting. Nelson mentioned not too long ago, that the susy principle will work best with low feedback ratios. What is low? < 20dB, or even less?
I believe that my circuits will have at least 60dB open loop gain (don't know yet), so for 10 dB gain we have a loop gain of 50 dB. Too much?

Well, I'll have to go sleep now...
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Old 6th April 2005, 10:29 PM   #20
zinsula is offline zinsula  Switzerland
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Quote:
Originally posted by MRupp
Shouldn't the JFETs be cascoded - I thought I read this in a post from Nelson Pass (would also similar to the Borbely design) ?
It depends, with source degeneration, not too much gain in the first stage and not too high input impedance, I don't think that it is an issue. But only listening will tell.....

Oh, yes, if we would like higher rails, then cascoding is a must. J-fets cannot take high voltage around them.

But now, definitly.....Buona Notte.
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