From: Jim Thompson
Subject: Re: Jensen 990/JE990/JT990 Discrete Op amp for audio applications
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Date: Fri, 04 Oct 2002 23:29:03 GMT
NNTP-Posting-Date: Fri, 04 Oct 2002 19:29:03 EDT
Organization: Cox Communications
On Fri, 4 Oct 2002 23:10:54 +0000 (UTC),
martingriffith@SPAMbtopenworld.com (Martin Griffith),
In Newsgroup: sci.electronics.design,
Entitled: "Re: Jensen 990/JE990/JT990 Discrete Op amp for audio
Wrote the following:
|back from the pub.....
|well, you can brew your own that can have high supply rails, so
|better headroom, check out doug self's site.Lots of improvements over
|the years,active loads etc... but Jim T knows more about opamps than
|I'll every know
|The 990 was designed in the days when transformer's ruled, and Jensen
|also happened to make transformers.......hmmm
|just some drunken ranmbling.......
That's the best kind of "ranmbling" ;-)
I suspect the easiest modern-day way to get low noise along with low
distortion would be to add a discrete diff-pair in front of an OpAmp.
Of course it may be mean to stabilize the feed-back loop.
I built my earliest pre amps from Ge transistors which tended to hiss
These were single-ended feed-back triples.
I'll have to try that scheme with some modern silicon devices and see
what I can get.
What amount of gain is needed?
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| Jim-T@analog_innovations.com Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
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