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Old 20th January 2013, 02:03 PM   #33061
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National Semi history, The parts were the LM100,LM104, and LM105. This history clearly states the the LM100 was released in 1966.
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Old 20th January 2013, 02:09 PM   #33062
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Quote:
Originally Posted by gk7 View Post
I do not want to enter a discussion about the audibility of the 7th harmonic, but just
wanted to show that in real circuits (as opposed to datasheets with measurements at
unity gain) it´s obviously there.
Actually, the datasheets in question don't show the devices at unity gain. Nor, contra John's false assertion, is this a phenomenon peculiar to ICs- some show it in some circuits, some don't, just like discrete.

If 7th and 9th are what separate "high end" from "mid fi," it's clear that good IC circuits are "high end." It's just not the particular fashion that John is selling.
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Old 20th January 2013, 02:22 PM   #33063
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"particular fashion" is more on the IC manufactures side with opamps (like OP275, OPA2604 etc." marketed "for audio".
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Old 20th January 2013, 02:24 PM   #33064
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Originally Posted by SY View Post
...
If 7th and 9th are what separate "high end" from "mid fi," it's clear that good IC circuits are "high end." ...
Well the OP227, OPA2604, AD8620 etc. would not qualify then.
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Old 20th January 2013, 02:25 PM   #33065
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All of them!
Actually, I get to read all the articles first!

jan
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Old 20th January 2013, 02:26 PM   #33066
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That depends on circuit, load, and level, no? I have no personal experience with those, so am agnostic. Likewise, there's no published spectra of the BT, so I have no idea if it's "high end" or not by that definition.
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Old 20th January 2013, 02:41 PM   #33067
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It's the reference that is really quiet - about 7uV IIRC. And, you can decouple it easily so it really is low noise. The LM3xx are about 30uV/V of output, to a 15V output has nearly half a mV of noise.
As Ed says who knows what's happened to the 723 process(es) now. The TI databook of 1996 shows a 5V output configuration as having 20uV of output noise 100Hz-10kHz with no lowpass filtering of the reference voltage of 7.15V, dropping to 2.5uV with 5uF bypassing the reference divider equivalent resistance of 10k. That's pretty decent. As this is certainly including some of the 1/f corner noise, and there is input diff amp current noise, that's still reasonably consistent with 7uV of mostly midband for the raw reference.

I should pull one out of ancient parts stock and measure it. I think I still have a couple in metal cans.
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Old 20th January 2013, 02:44 PM   #33068
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What separate "high end" from "mid fi" rely on a very measurable measurement data: Price.

While i'm not able to hear any obvious difference in my system between my preamp (Ic based) and a short wire, i do not ask myself questions about any evils.
Of course, this have only a very subjective value, as i'm unwashed with poor hearing ability, comparing to John's one, if we believe in what he pretend.
In a way, it can be correlated with his aversion to CDs, while i enjoy a lot of them.
As well as my strange ability to suffer evil compression drivers and horns.
Sure he is able to hear things that i do not.
I strongly recommend to everybody to try to be as deaf as i am, as it save a lot of money and brings so much pleasure, listening to good music, not available on an other support than CDs. on a system you are not obliged to change all the weeks.
Oh, one good thing about ICs is you can try in a snap the ones which make no differences, and no need to make any measurements.
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Old 20th January 2013, 02:58 PM   #33069
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Here is how the LM105 works BETTER than many IC regulators. Note Bypass pin where you at a 10uF cap to ground to lower the noise from the reference.
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Old 20th January 2013, 02:59 PM   #33070
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Quote:
Originally Posted by john curl View Post
First part of a good article on contacts:
Jonn,

Could you, please, post the second part of this Antler's paper? I'd love to read it to the end. Thanks!

P.S. For those that are interested in this topic, here's another paper by the same author that I was able to dig up.
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