John Curl's Blowtorch preamplifier part II - Page 1915 - diyAudio
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Old 13th December 2011, 03:05 AM   #19141
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As usual, strong comments are made without any experience.
Let me give you one example of MY experience with line cords.
Personally, I don't like to spend extra money on line cords, but that does not say they are not audible. Please don't 'knock it' if you haven't tried it.
In any case, I had an interesting experience about 20 years ago, at CES.
A music producer that I had worked with since 1977, off and on, was doing an A-B test with power line cables.
Now, I had known and worked with this guy through 3 enterprises that he created. First, in the late 70's he had an audio magazine that I once contributed to.
At the same time, and after, he started and ran 'Crystal Clear Records' a direct disc recording company with many, many titles. I designed the electronics for his recording desk back in 1977. John Meyer (of Meyersound) was his technical consultant and he and I both recommended B&K 4133 condenser microphones running at full voltage.
A listening example of our efforts was: 'Arthur Fiedler and the Boston Pops' made in 1977 with direct disc mastering.
Anyway, he was at CES and was demoing power cords about 20 years ago.
Did we hear a difference? Yes we did, but he wanted so much money for these cables that we 'wrote it off'. Yet, the difference was there, AND for someone with means, actually a bargain for the improvement in the sound, which is difficult to get, once you have really good equipment, already. To say it is BS, is unfortunate. Live in ignorance, then. '-)
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Old 13th December 2011, 03:35 AM   #19142
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Are you saying John that John Meyer can confirm your finding about power cords?
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Last edited by Wavebourn; 13th December 2011 at 03:41 AM.
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Old 13th December 2011, 04:09 AM   #19143
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No, John Meyer and I have not worked together for decades. He tends not to believe things like this. No, I was with a different set of associates.
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Old 13th December 2011, 04:14 AM   #19144
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Quote:
Originally Posted by pski View Post
Please refer to Ohm's law concerning your old 15 amp AC. The wire in the transformer? GEEZ. It's the winding, not the gauge.
I think you completely missed my point. Yes, it's the number of turns in the primary that determines impedance. There's this thing called mutual inductance. The load applied to the secondary affects impedance too. And to say any more I have to dig out an old textbook, cause I don't remember all that stuff now.

So, if a person shorts the output of the secondary and the core starts to melt, the wire inside the transformer will still be a long wire and the gauge much less than a 6mm.

Hmmm ... so how the F#@$ does having a 6mm AC line help anything?
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Old 13th December 2011, 04:20 AM   #19145
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Here's a link to some history of early digital recordings.
It includes additional information on Crystal Clear Records and other items that John C. has mentioned.

http://goo.gl/rtn39

Just thought this might be interesting to some of you folks.

Cheers.

ZAP
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Old 13th December 2011, 04:27 AM   #19146
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how do you justify using a gage#11 power cord on an amp that has a power traffo with primary winding using gage#20 and then plug that power cable into a wall outlet that has a gage#14 cabling?
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Old 13th December 2011, 04:35 AM   #19147
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You have very true signature, Tony.
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Old 13th December 2011, 05:22 AM   #19148
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I would like to attract attention once again to chokes in power supplies of AB amps. Maybe some substractions from a textbook (its in russian) could help me to explain the point: chokes (10mH and more) help a bit to have more favorable spectrum of charging pulses, but they do increase voltage drops at filter capacitors during current consumption peaks and affect negatively sound dynamics.
As a conclusion, chokes are not recommended for AB amps, except for maybe configuration shown in fig.36, with external or well screened part of PS, and with abnormally big C3 and C4 (in order to compensate negative effects of chokes)
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File Type: jpg Choke input PS.jpg (35.1 KB, 144 views)
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Old 13th December 2011, 05:36 AM   #19149
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You are correct, Vlad. We call Fig. 36 a pi filter, in the USA. CLC

Last edited by john curl; 13th December 2011 at 05:39 AM.
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Old 13th December 2011, 05:47 AM   #19150
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Vladimir; there are some other Russian books, for example: http://www.znvo.kz/images/book/dobrotvorskyin.zip
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