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Old 5th April 2005, 02:53 PM   #1
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Default X2_ugs3,4

Dear all,
You might laught at me to ask such question :
I have downloaded the X2_Rev 0,1,2 &3.
Where I can find the full detail schemtic of "UGS3,4" ?

Best Rgards !

Thomas
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Old 5th April 2005, 03:54 PM   #2
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Thomas,

Nelson has already explained that, search for X2 last month.

Alain.
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Old 5th April 2005, 07:46 PM   #3
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Nelson still uses the UGS modules as parts in his current product line, and thus will not release it's details.

To answser another of your questions to me on the volume control, for the X2's you simply need a normal stereo attenuator. Since my CC-CCS-X-BZLS does all SE-Bal & Bal-Se conversion and provide gain in a single stage, I had to resort to a balanced stereo attenuator. I sourced mine from Parts Connexion. It is a 4 deck, single pole per deck, 23 position switch by Electroswitch, with 96 Holco resistors.

Cheers, Terry
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Old 5th April 2005, 09:46 PM   #4
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It seems to me that I recently received some email from
somebody who reverse-engineered a UGS and gave an
accurate enough description, asking for permission to
post it, which he didn't need but which I gave. I haven't
seen it here, though.

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Old 6th April 2005, 06:07 PM   #5
vit is offline vit  Sweden
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Who ever you are, don't be shy

Pot sem muj kocourku...
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Old 6th April 2005, 07:29 PM   #6
gl is offline gl  United States
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Yes please, I too would be interested in this.

Once upon a time I thought I had the UGS figured out and was going try building a proto. NP has very graciously dumped lots of breadcrumbs on this particular trail. From info he had given plus photos on the Pass Labs site it appeared that the UGS was a JFET/MOSFET implementation of Fig. 2 of patent 5,376,899. However, one post by on 11/20/03 put the kibosh on that.

A member (petter) writes:

"Many of Pass' recent designs that have been in the public domain use folded cascode. All X series units by definition need to use it (with the possible exception of the XA range). If you think about it, how else can you make a fully DC coupled single gain stage where the input DC level is the same as the output DC level?"


NP responds:

"Actually not true. Folded cascode is not essential, and appears in
in two commercial Pass Designs, the X600 and X1000 (which have
exactly the same circuit board. The lesser X designs are seen to
use ordinary cascoding on the front end.

In the XA designs we have no cascoding, and that would be consistent with the Aleph circuitry. That does not mean it
might not eventually make an appearance somewhere, folded
or otherwise."



At this point I find it difficult to figure out a number of elements, for instance the two pots. So yes, whoever you are, please post your ideas.

GL
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Old 6th April 2005, 08:05 PM   #7
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One of the two pots adjusts absolute offset, the other
differential offset.
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Old 6th April 2005, 08:16 PM   #8
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Quote:
Originally posted by vit
Who ever you are, don't be shy
At the risk of creating trouble, I looked it up and it was....

***** ACAUDIO *****



Although at the time he still had some work to do on it.
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Old 6th April 2005, 08:43 PM   #9
acaudio is offline acaudio  Germany
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Quote:
Originally posted by Nelson Pass


At the risk of creating trouble, I looked it up and it was....

***** ACAUDIO *****



Although at the time he still had some work to do on it.


Ok Guys,
here is it:

Its alive!

-> Adam
Attached Images
File Type: jpg my ugs1.jpg (63.0 KB, 4484 views)
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Old 6th April 2005, 08:54 PM   #10
Bricolo is offline Bricolo  France
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That's even more cruel that saying nothing
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Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease
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