John Curl's Blowtorch preamplifier part II - Page 3299 - diyAudio
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Old 19th January 2013, 06:10 PM   #32981
SY is offline SY  United States
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Quote:
Originally Posted by Waly View Post

You would pull anything out of thin air to make a point, isn't it?
Even with cheating, the number is ridiculously low.

The tip o' the hat to John is Ed's use of 1968 components for examples, so even my numbers were enormously higher noise than you get from modern ICs.
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Old 19th January 2013, 06:22 PM   #32982
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Ampex ATR-102 half-inch two-track, (not modified by John curl :-) with extended low frequency heads, 30 IPS. This is at Studio X in Seattle.
Click the image to open in full size.

And this a Pc based with Starmax MT3200 computer's onboard A/D converter
Click the image to open in full size.
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Old 19th January 2013, 06:23 PM   #32983
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What I like best is the 1966 voltage regulators made by National. They were quieter than almost anything, today!
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Old 19th January 2013, 06:24 PM   #32984
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Great bass with digital. Too bad about the higher frequencies.
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Old 19th January 2013, 06:37 PM   #32985
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To rephrase a point JC was making ---

1. The IC's neg feedback network is in parallel with its load Z ... giving a much lower Z than the input of the power amp would imply.

2. In order to obtain the noise level spec of the IC, it would need very low Z in the neg feedback network.

3. low Z feedback network reduces the max output in the spec sheet.

4. You cant get all the specs in one circuit with fixed values.

have I got that right, JC?

-Thx- RNMarsh
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Old 19th January 2013, 06:38 PM   #32986
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Quote:
Originally Posted by john curl View Post
Great bass with digital. Too bad about the higher frequencies.
This is a 48 KHz recording. Double the frequency for a 96, quadruple with a 192kHz, while i doubt you will hear any listening difference.
May-be asking your dog on his paws crafted enclosures ?
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Old 19th January 2013, 06:39 PM   #32987
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Thanks Richard. A-OK
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Old 19th January 2013, 06:40 PM   #32988
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My analog tape recorders could record to 45KHz, so there! '-)
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Old 19th January 2013, 06:48 PM   #32989
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Quote:
Originally Posted by john curl View Post
What I like best is the 1966 voltage regulators made by National. They were quieter than almost anything, today!
Hear, hear, the golden 60's .

Ever tried the TPS7A470 and it's negative version TPS7A3301? 16uV noise in 100KHz BW, one order of magnitude lower than the National 60's negative regulators. And 4uV for the positive version.
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Old 19th January 2013, 06:54 PM   #32990
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Originally Posted by RNMarsh View Post
4. You cant get all the specs in one circuit with fixed values
You yet knew all that very well, Richard :-)
This said, we can notice that, when we need gain and low noise, we do not need high output levels and currents, and when we need current for output buffers, we do not have to care too much about gain or noise.
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