John Curl's Blowtorch preamplifier part II - Page 1853 - diyAudio
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Old 29th November 2011, 11:36 PM   #18521
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Quote:
Originally Posted by john curl View Post
OK This is what I have found, in my experience, how to make the best electronics possible, all else being equal.
1. Just using purely passive high quality parts is as good or better than almost any amplified electronics. (What I use in my office for a preamp)
2. IF you have to use electronic amplification, then use a minimum path, as linear as possible, zero global feedback, and a very high open loop bandwidth. (Blowtorch, Vendetta first stage)
3. If you MUST use global feedback, use as fast and as high open loop bandwidth as possible. This is important! Also make the circuits as linear as possible, within their marketing constraints. (JC-2, Vendetta second stage, Constellation second stage, JC-1 power amp, JC-3 power amp, JC-80 preamp)
4. IF you must use IC's, try for fast and video ready ones, IF POSSIBLE. If not, especially for extra low noise, use the best parts that you can find, and SUBJECTIVELY listen to each and every one type, and select what sounds best to you. (JC-3 phono preamp)
In every case, use the best passive parts, best power supply, capacitors, connectors, wires, etc that you find works for you, and usually, others in the field.
If you follow these suggestions, you will normally be ahead of the pack in making an audio quality product, be it for yourself, or for the general public.
Interesting someone sent me an article by Dick Burwen today, he feels about the direct opposite. FWIW you can go a long way in audio following your rules, sometimes we cross precision instrumentation with audio. Playing an LP is not the same as weighing something to 6 digits.
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Old 30th November 2011, 01:07 AM   #18522
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Well, Dick Burwen and I have differed for the last 38 years. So what? He is a good designer, but he used to think that 100 earlier op amps in series were impossible to detect. (true story)
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Old 30th November 2011, 02:06 AM   #18523
kevinh is offline kevinh  United States
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If I understand his POV he feels that issues with the recording (issues with digital signals) frequency response out weigh the impact of the electronics. Hence pieces like the Cello Audio Palette.

Different strokes.
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Old 30th November 2011, 02:30 AM   #18524
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I have a Cello Audio Palette. The big model. It can improve bad recordings tremendously but it also adds some noise and fog.
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Old 30th November 2011, 02:42 AM   #18525
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Hi,

Quote:
Originally Posted by john curl View Post
Well, Dick Burwen and I have differed for the last 38 years. So what? He is a good designer, but he used to think that 100 earlier op amps in series were impossible to detect. (true story)
Funny story.

Back at that small east german maker of studio electronics I worked at in the 80's we used to do bypass tests with various sets of components or complete cassettes. One bypass test used four or six of our transformers in series (connected for unity gain of course) and at least in our test setup, based on Schulze Studio Monitors, we felt we were unable to tell these four or six transformers reliably.

But we could tell the insertion of a single B761/TAA761 (a german Audio Op-Amp, quite interresting, open collector output, SE Class A output, input differential folded cascode somewhat similar to what JC does, 85dB OLG with around 10KHz OLG Bandwidth, externally compensated, actually, a quite good Audio Op-Amp for the times I would say)...

Ciao T

Last edited by ThorstenL; 30th November 2011 at 02:52 AM.
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Old 30th November 2011, 04:51 AM   #18526
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Dick Burwen taught Mark Levinson about quality parts, soldering, and wire. He worked for Mark as a consultant for 1 or 2 years before I did. After I was hired, we replaced virtually every op amp module with one of my own design, at Mark's insistence.
Later, when I was long gone and Levinson was effectively sold to HK, Mark commissioned Dick Burwen to make the equalizer, and it is perhaps one of the best equalizers ever made. The only unit that I have experience with that might be better is an early Sontec (sp) unit made in the mid-70's, and designed by George Massenburg.
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Old 30th November 2011, 05:19 AM   #18527
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Thorsten, could you put up the schematic for the TAA761? I am having trouble finding it. I suspect that Studer used something like this with an output stage in 1973, for there A80 MK 1 master recorder.
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Old 30th November 2011, 06:27 AM   #18528
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.........
Attached Images
File Type: png East OPAMPs A.png (143.3 KB, 177 views)
File Type: jpg East OPAMPs B.jpg (77.2 KB, 177 views)
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Old 30th November 2011, 06:41 AM   #18529
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B611D - operační zesilovač, TTL výstup, datasheet

One can buy them on-line

http://www.denkl.cz/eshop/b-611-d-8788
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Last edited by PMA; 30th November 2011 at 06:43 AM.
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Old 30th November 2011, 06:53 AM   #18530
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Thanks Joachim and PMA. I finally got something, myself, but it took some effort.
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