John Curl's Blowtorch preamplifier

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metalman

metalman

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Joined 2003
jneutron said:


the relevant parameter is called RRR, or residual resistivity ratio. It is a parameter of the metal that defines what it will do at low temperatures. For superconducting magnets, it's an important parameter for the superconductor stability prior to a quench, and defines the thermal and electrical conductivity of the metal in the presence of a magnetic flux, usually in Teslas.
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The metallurgist / materials scientist in me had to comment. John and John are making perfectly proven points, except that they are only valid if you are operating your conductors at extremely low temperatures. Anywhere near room temperature these effects are essentially negligible. Last time I checked most of us didn't keep our cables ina dewar of liquid nitrogen or liquid helium.

Cheers, Terry
 
Wavebourn

Wavebourn

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wavebourn.com
john curl said:
I normally find your 'humor' based on derision or satire. You are such a nice guy in person, and even over the phone, that it must be caused, in part at least, on cultural differences between us.
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Satire is not my humor; I use satire when I defend myself. Like, when somebody calls my design wrong, when actually it is just an another approach, or other criteria were taken in mind that the critic don't think about.
 
john curl

john curl

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Joined 2003
Metalman, you missed the point. I started to talk about the RESIDUAL RESISTIVITY of conducting metals, but we got sidetracked with Dr Hawksford, misplaced humor, and other things.
First, the TEMPERATURE of the metal is what I am not concerned with. Essentially, in a gross way, one might say that the measured resistivity of a metal is almost completely dependent on temperature, BUT it is the RESIDUAL RESISTIVITY that might change the formula enough, even though it is difficult to measure and access within the normal resistivity. Who is sure that the residual resistivity is not more of a problem at low signal levels? That is my question, just like why does a small amount of certain kinds of harmonic distortion make a sonic difference?
What is this residual resistivity composed of. Is it really LINEAR? (I actually don't know the answer exactly, myself.)
 
jan.didden

jan.didden

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linearaudio.net
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PMA said:
I returned to hifi audio, as a hobby, some 7 years ago, after 20 years gap (20 years ago I built something and believed it was beyond audibility limits :D :D ), first only as a hobby, then it became a small part of my design, consulting and business activity.

6 years ago I would swear that cables make no difference, impossible, nothing to measure, nothing to hear.

5 years ago I would swear opamps are the best audio solution.

3 years ago I had quarrels with John here (my apology).

During those 6-7 years, my view at audio has completely developed and changed. Without continuous listening experience and comparisons, my view would have been the same as 7 years ago.
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PMA,

Interesting travel. Now brace yourself: the next 7 (or 14) years will even change you more. If you continue to question, of course.
;)

Jan Didden
 
PMA

PMA

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pmacura.cz/audiopage.html
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Jan,

IMO, the people who insist on inaudibility of opamps vs. discrete, signal cables change etc. :

- do not listen to reproduced music too much,
- do not have much experience with various high quality systems,
- do not have good sound source and good recordings,
- have wrong placement of speakers or bad room acoustics,

- or are just engineers who do not listen at all.
 
jan.didden

jan.didden

AX tech editor
Joined 2002
linearaudio.net
Paid Member
PMA said:
Jan,

IMO, the people who insist on inaudibility of opamps vs. discrete, signal cables change etc. :

- do not listen to reproduced music too much,
- do not have much experience with various high quality systems,
- do not have good sound source and good recordings,
- have wrong placement of speakers or bad room acoustics,

- or are just engineers who do not listen at all.
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Hmm. Not really a great basis for constructive discussions. There are not many people who succeed to find the Absolute Truth (tm) in only 7 years. ;) .

I was just trying to encourage you to continue to question and search. Knowledge is like an onion: when you finally peeled back the skin to find what's underneath, you find - another onion ...

Jan Didden
 
J

JPV

Member
Joined 2006
phantomillumination.com
PMA said:
Jan,

IMO, the people who insist on inaudibility of opamps vs. discrete, signal cables change etc. :

- do not listen to reproduced music too much,
- do not have much experience with various high quality systems,
- do not have good sound source and good recordings,
- have wrong placement of speakers or bad room acoustics,

- or are just engineers who do not listen at all.
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There must be a lot of second order effects that are difficult to model and quantify. Quantification is an important issue.

I would like to have your comments on my posts on thermaltrack Vbe tracking
http://www.diyaudio.com/forums/showthread.php?s=&postid=1649577#post1649577

I can be wrong but at least there are some quantification aspects to this problem that should be compared with the experience of a qualified music listener.

Thanks

JPV
 
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