John Curl's Blowtorch preamplifier part II - Page 661 - diyAudio
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Old 14th November 2010, 01:44 AM   #6601
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Here is a white paper. i was not successfull to upload it so here is the ULR :
http://wduk.worldomain.net/pdf/Clari...cal_Report.pdf
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Old 14th November 2010, 02:06 AM   #6602
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Thanks Joachim, interesting cap test.
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Old 14th November 2010, 02:14 AM   #6603
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Originally Posted by john curl View Post
Second, Bob Crump found that transformer leakage could be important sonically. Why, I cannot easily explain, but Bob found that the 'housekeeping' transformer to be leaking AC voltage on the chassis and that reversing its windings, helped.
I am finishing a book review and this is one point I cover in detail. The explanation is simple. You want the AC line neutral wire connected to the windings closest to the transformer core. Otherwise you will actually induce a small AC current into your chassis! Happens on all transformers! How much leakage current depends on the transformer design and quality.

Interconnect two pieces of gear and you will have a small current flow between them.
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Old 14th November 2010, 02:30 AM   #6604
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In Germany it is virtually imposible to sell expensive High End equipment when the AC line is not marked for phase. A lot of equipment has now an indicator bulb or a display message for this. A fried in Vienna ( Mace Audio ) was able to measure an increase in distortion in his poweramp when the AC line was connected the " other way around ".
In a country like Norway this seems to be less of a problem beause the AC line is symmetrical. Still my audiophile friends there listen what way around it sounds best. As i already reported some time ago, audiophiles in Japan are absolutely fanatic about "direction" and i really had to guaranty my importer back in the 90th that the coils in my speakers are wound " from the inside to the outside, the right way around". I can not remember if the "good" winding direction was left or right and i do not claim that i can measure or hear that but i second Johns experience 100% that to be successfull in "the real world" ouside the lab measures like that have to be taken to satisfy demanding customers. If they are a victim of their own imagination i can not tell and that is not my duty.
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Old 14th November 2010, 02:30 AM   #6605
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Thanks Simon. We have known about this since the vacuum tube days and unpolarized AC line plugs (2 prong). Why this happened was always a mystery to me.
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Old 14th November 2010, 02:31 AM   #6606
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Originally Posted by john curl View Post
Thanks Joachim, interesting cap test.
Right, one big commercial for a bunch of bull dada.
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Old 14th November 2010, 02:47 AM   #6607
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At least Clarity Caps in England invested to make a cap that is mechanically strong based on what they found. It is the MR range and everybody can try them if they make any difference or not. I do not use them because i work traditionally with German suppliers for my German Products and Allen Perkins in Berkeley who produces speakers that i designed for the American and international marked uses American suppliers if that makes sense to you. Still i was surprised that the american supplier uses " foils from Germany, they are the best", so people that actually make "audiophile" parts ( at least this particular supplier ) care about the ingredience and physical behavior of the raw materials they buy.
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Old 14th November 2010, 02:52 AM   #6608
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From the cap test.
"...driving with a sine wave, like an audio signal, will produce a mechanical force at twice the driving frequency; an example of this ‘frequency doubling’ effect is shown below. This raises the issue of the capacitor being a possible source of intermodulation distortion products at double the frequency of any audio signals present."

Funny, I thought that was called 2nd harmonic distortion. Also seen in single rail power supplies. Is this something else?
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Old 14th November 2010, 02:54 AM   #6609
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As far as i know the University of Salford did an AES paper about their findings but it did off cause not make it into the Journal.
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Old 14th November 2010, 02:58 AM   #6610
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Yes, double the frequency is second harmonic distortion but i do think that they where searching for the physial cause of this phenomenon.
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