John Curl's Blowtorch preamplifier part II - Page 2948 - diyAudio
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Old 18th November 2012, 08:41 AM   #29471
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We did Listening Tests on cables in 1979 Absolute Listening Tests-Further ProgressThere was a clear winner; Lightning Conductor. But even this wasn't 100% (audibly) accurate. There were some appalling Golden Pinnae 'low inductance' cables.

Dunno if our LC was O2 free but I doubt very much if any new millenium cable beats our 1979 winner.

Oh! and you can easily measure the differences and see if what goes in also comes out.
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I sorta expected JC's answer to the challenge and it is unfair to subject him to a Blind Listening Test when his performance has already been tested. But I was hoping he would suggest some people with 6 sigma hearing to do battle on his behalf.

BTW, I was expecting him to spend however many hours/days it takes to set up Blowtorch first with his ancillaries so there is no doubt Blowtorch is performing optimally. Then his A team leaves the room while the Dynamic Duo + John Atkinson set up the competing B & C systems without disturbing JC's A team system. Finally the DD swap the A, B & C labels and battle commences with the Blind Listening Test Panel.

Need at least 5 in the panel for statistical significance on the DUT. Less if we are just testing the Panel (checking & calibrating the measuring instrument.) John Atkinson has my vote for a true golden pinnae. The DD can provide at least one more from their ABX team. Apologies to any statisticians out there.

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Old 18th November 2012, 09:13 AM   #29472
RNMarsh is offline RNMarsh  United States
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Default Low Ls is one factor for spkr cables -

Quote:
Originally Posted by kgrlee View Post
We did Listening Tests on cables in 1979 Absolute Listening Tests-Further ProgressThere was a clear winner; Lightning Conductor. But even this wasn't 100% (audibly) accurate. There were some appalling Golden Pinnae 'low inductance' cables.
I doubt that the appalling cable actually was very low Ls. Did you measure it? And what is the Ls of the "winning" cable? What are the numbers of each?
Never-the-less, low Ls is better than high Ls for dynamic tweeters if you dont want attenuation. But it is interesting that you did hear differences between speaker cables. Thx-RNM

Last edited by RNMarsh; 18th November 2012 at 09:15 AM.
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Old 18th November 2012, 11:22 AM   #29473
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Ricardo, there's no motivation for spreaders of legends to cooperate with the puncturing thereof. They're selling fantasy, and their buyers are getting what they want. Why even bother to ask?
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Old 18th November 2012, 11:23 AM   #29474
SY is offline SY  United States
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Quote:
Originally Posted by RNMarsh View Post
Never-the-less, low Ls is better than high Ls for dynamic tweeters if you dont want attenuation.
You may want to run some numbers of actual wires and tweeters to determine significance.

This has been hashed over repeatedly, and Dick Greiner's excellent analysis still stands.
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Old 18th November 2012, 12:30 PM   #29475
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Bob Cordell's recent (and excellent) book makes a suggestion that others may have already known, but that was new to me. If worried about parasitic reactances in a long speaker wire, include an appropriate Zobel at the speaker end. Cheap peace of mind. Obvious after ya hear it.

He also recommends one at line level inputs, maybe 75 Ohms and 100pF. I can't recommend the book too highly.

Thanks,
Chris
Tried this about 10 years ago, works well. The effect is measurable as a lower RF content.
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Old 18th November 2012, 01:18 PM   #29476
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Well, I suppose that SY is right. I AM selling a legend. After all, the CTC BLOWTORCH ended production, about 6 years ago, and will never be started again, so why have I been talking about how we built the Blowtorch preamp on this thread, over about as many years?
My reason was to pass on what we found WORKED in making the Blowtorch, and to fend off petty criticism of our approach to this project that we did when money was not so tight, and some customers just wanted the 'best' without regard to price.
Some might say that the Blowtorch was OVERBUILT and it could have been made much more cheaply. I say, go for it! If you or anyone can build something much less expensively that truly sounds just as good in their listening system over an extended period of time, then go out there and sell it to the public, with my blessing.
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Old 18th November 2012, 02:23 PM   #29477
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Originally Posted by RNMarsh View Post
You will have problems if they are not gold flashed surfaces/contacts/fingers. And, RFI rectification and harmonic generation is one such problem along with the usual (intemittant, noise, hum, etal).
ADSL has been shown to work over (unshielded ) razor wire.
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Old 18th November 2012, 02:55 PM   #29478
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Quote:
Originally Posted by kgrlee View Post
We did Listening Tests on cables in 1979 Absolute Listening Tests-Further ProgressThere was a clear winner; Lightning Conductor.
Did the same kind of tests with a very stable amp . Some subtle differences found with a pair of enclosures witch had a mountain like impedance curve.
No difference found with the BIG main monitors of the studio, witch where using a passive filter with near flat impedance curve (Impedance compensations).
I believe the only differences in first case was due to the serial resistance of the wire.

Any way, the differences we found were less than the ones we can feel one day after an other, due to humidity levels changes. And less than the ones you can get playing with the compensation cap in the feedback loop or the internal zobel of the amp.
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Old 18th November 2012, 03:07 PM   #29479
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Originally Posted by john curl View Post
My reason was to pass on what we found WORKED
The problem, John, is statements like direction of wires or breaking them are nonsense. Thus detracts from your technical credibility.
I can understand why snake oil vendors can play with such myths and legends near naive audiophiles, but, please, NOT YOU, John, Not you ! And not with us.
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Old 18th November 2012, 03:26 PM   #29480
gpapag is online now gpapag  Greece
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Quote:
Originally Posted by kgrlee View Post
See "Loudspeakers as Microphones" - Peter Baxandall special lecture London AES (early 80s, late 70s?)

More sophisticated but similar (??!) is ACE technology by Erik Stahl which was used by Audio Pro, Sweden for subs.
Thanks for the info

Baxandall paper
http://www.collinsaudio.com/Prosound...icrophones.PDF

Two forums discussing ACE-BASS
STAHL - 'Acebass' Synthesis of Loudspeaker Mechanical Parameters by Electrical Means

ACE-bass amplifier design
George

P.S. kgrlee, I have mentioned neither reputation nor usual exagerations. Just courageous professional life path.
Who are the “Dynamic Duo “?
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Last edited by gpapag; 18th November 2012 at 03:30 PM.
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