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Old 22nd April 2011, 12:27 PM   #1
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Default Jim Williams designs a new Super Oscillator

In the mail-bag from Audio Precision -- you might find this blog-article (it's a tease by the editors of EDN) interesting. And some of the respondents include RAP!:


Audio Precision to the rescue, of Jim Williams no less - Anablog | Blog on EDN
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Old 23rd April 2011, 11:04 PM   #2
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-160db? Shazbat! Note the ground planes and shielding.
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Old 25th April 2011, 06:50 AM   #3
Frex is offline Frex  France
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Hello jackinnj,

Yeah, it seem to be a new great work from Jim Williams !
Now, i'm pretty impatient to read the next EDN issue.
And maybe we could build it to try that ...


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Old 25th April 2011, 10:32 AM   #4
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I have used some AP kit and its awsome, too expensive to have at home though and a PC sound card can do the same mesurments with less conveniance as the cheaper units. The artical claims the oscilator in the AP hardware is lower noise still and adjustable?!?!
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Old 25th April 2011, 10:47 AM   #5
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I always read 'Anablog', also 'Powersource' and 'Scope Guru'

This was a very interesting one, replies include both Bob Pease and Jim Williams himself!
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Old 25th April 2011, 12:07 PM   #6
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Bob's comment is like mine, I squeezed -150dB out of my old Sound Technology 1700B in 1992 with a few tricks (good enough for me). I talked with Jim about "distortionless" oscillators with distortion trims last time I saw him. If you can get a copy of his AES talk and especially his references you can get the whole story. It turns out, in my case, the way a Wein bridge "really" works was buried in an obscure text book I had at MIT. Jim's reference from HP labs covering the same issue is in his words, "The best piece of engineering he has ever seen".
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Old 25th April 2011, 02:42 PM   #7
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Jim sent me a copy of the article. It was Bernie Oliver's cover article in the Apr.-June 1960 issue of the HP Technical Journal. The gist is you can't simply make a distortionless Wein bridge oscillator. Bernie argued one way and my text used it to explain the usefulness of Volterra math (comming essentially to the same answer). I can't wait to see the latest incarnation, I'm sure Jim has a few secret rooms with virtually unavailable exotic components.
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Old 25th April 2011, 02:49 PM   #8
klewis is offline klewis  United States
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Default analog scope in crossplot mode

Not being able to aford an AP just yet, can anyone point me to an article, book or reference on how to use a scope in crossplot mode to measure distortion?

Thanks
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Old 25th April 2011, 03:11 PM   #9
jcx is offline jcx  United States
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'scopes and eyeballs are pretty poor in distortion resolution - better soundcards are really excellent in the audio frequency range
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Old 25th April 2011, 04:20 PM   #10
carpin is offline carpin  Netherlands
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Quote:
Originally Posted by klewis View Post
Not being able to aford an AP just yet, can anyone point me to an article, book or reference on how to use a scope in crossplot mode to measure distortion?

Thanks
The EDN designer's companion
By Ian Hickman, Bill Travis
see page 188

link The EDN designer's companion


Distortion Measurement audio amplifiers
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