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Old 23rd August 2012, 02:28 PM   #81
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Quote:
Originally Posted by bcarso View Post
Number two (from post 68) is not too bad. Whose is it? It looks like something that really works.
What?!?! you didn't see the "Je-990" on that one? I assume you mean this one in the middle?
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Old 23rd August 2012, 02:30 PM   #82
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Two of the first lot?
JE-990!

hee hee.

Or did you mean the second lot as a whole??

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Old 23rd August 2012, 02:31 PM   #83
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Quote:
Originally Posted by scott wurcer View Post
Sorry guys EVUL started this so fast I was caught off guard. I hope to put up a couple of ideas later today. I don't think complexity is a goal in itself, performance is. I also don't think a design contest with an 8 transistor limit should be a prime goal.
OK, so re-write the rules then....

What IS the goal? So far, it's been talking about this transistor vs. this other one and whether or not it's still produced.

I actually don't like the differential opamp topology anyway. I don't use it (when I play around in my spice simulator) except for power amps.
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Old 23rd August 2012, 02:40 PM   #84
bcarso is offline bcarso  United States
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Quote:
Originally Posted by dirkwright View Post
What?!?! you didn't see the "Je-990" on that one? I assume you mean this one in the middle?
My bad. The one in the middle from post 70, with the dual JFET front end. I like that one.
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Old 23rd August 2012, 02:54 PM   #85
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Originally Posted by bcarso View Post
My bad. The one in the middle from post 70, with the dual JFET front end. I like that one.
You'll have to ask ThorstenL about that one.

http://www.diyaudio.com/forums/analo...t-ii-1886.html

All I got so far is that it is very old. (1973?)

I was just posting random schematics to get the creative juices going here. I don't mean to endorse one over another one. I'm not really knowledgeable enough to know which would be better than another anyway.

Last edited by dirkwright; 23rd August 2012 at 02:57 PM.
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Old 23rd August 2012, 03:49 PM   #86
bcarso is offline bcarso  United States
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Originally Posted by dirkwright View Post
You'll have to ask ThorstenL about that one.
I hope he can be persuaded to return someday. However, this seems to be the season for leaving sites (I recently left a couple of "social" ones, no doubt pleasing some and disappointing others).
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Old 23rd August 2012, 03:53 PM   #87
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Default JE990

Quote:
Originally Posted by john curl View Post
Anything less complex than a Jensen 990 is a joke, and not worthy of consideration. We are looking for EXCELLENT circuits that we would use in the best audio equipment available today.
One of the 990's best characteristics was it's stability into (relatively) difficult loads. It was designed by Deane (RIP) to drive his transformers (albeit he recommended output isolators) so it had to be stable. The 990 was quiet enough to make a high-end MM RIAA preamp in 1988, as executed in the PR&E (Pacific Recorders & Engineering) TX990, still a great-performing pre (see attached pix)

Howie

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As a footnote, I worked tangentially with Bill Whitlock (now Jensen Pres) at Capitol Records when they decided to ditch their own digital duplication bin and install our DAAD system. He is one of the brightest engineers I have ever worked with. He came from Quad-8 (as did Deane) interestingly enough, since a Quad-8 amp schematic has just been posted...
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File Type: jpg TX990a.jpg (118.7 KB, 633 views)
File Type: jpg TX990b.jpg (89.2 KB, 565 views)
File Type: jpg TX990c.jpg (68.9 KB, 530 views)
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Old 23rd August 2012, 04:02 PM   #88
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Samuel Groner has shown the most popular topologies for Opamps.
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File Type: png Folded cascode with bootstrap.png (28.3 KB, 347 views)
File Type: png 2 stage Opamps.png (28.3 KB, 233 views)
File Type: png 3 stage Opamp.png (49.2 KB, 349 views)
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Old 23rd August 2012, 04:03 PM   #89
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Sorry, two are missing.
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Old 23rd August 2012, 04:06 PM   #90
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Here we go...
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