John Curl's Blowtorch preamplifier

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PMA said:


So it is a real "Uskok"? (feint, jump aside)
You know approx. meaning of the world "Uskok", we both speak slavic languages. But "Uskok" is the name of the old-time Serbian/Croatian freedom fighter living at the seaside who used to jump from his small ship to well armed large enemy ship board starting battle. It is entirely different from meaning "pirat" as you suggested.
 
scott wurcer said:



Copyright does not apply to the design only the actual drawings and photos, and personal use only disclaimers actually have no legal standing in the US. I wish someone had info on the laws in the EU.

Indeed, there is a significant difference between "copyright and "patent".

All intellectual property protection systems share a few characteristics. Among them, the "diclosure" principle. You cannot infringe an IP if it was not prior disclosed, either in a patent or otherwise published. From this perspective, any claim that a Blowtorch IP was infringed would be without any merit in justice. If an asian manufacturer starts tomorrow a mass production of Blowtorch clones, then there's nothing that JC or his associates could actually do about.

And why is this not happening? Simply because Blowtorch is much more than a (very good) design and an implementation: it's a legend. This legend has many sides, starting with JC and ending with the respectable price. Almost nobody will buy a $500 Blowtorch clone, even if it would be objectively and subjectively identical to the original.

Of course, there's much more than copyright and patent infringements. Not quoting or crediting prior work is, in our culture, ugly and denotes at least some gaps in the moral fiber of an individual. Though, don't forget that not all cultures have the same set of values as the West.
 
1audio said:
A few provocative thoughts:
[snip]2) When the human perception engine is in the chain between a performance of some sort and the perception of the performance where do we stay as neutral as possible and where do we attempt to predict and enhance/alter the signal to improve/reduce the degradation of the performance by the effects of the chain? Since we are not in the room the performance was in with all of the sensory and experiential components (including the dinner before or the nitecap after) not to mention the ability (missing in real life) of the instant replay, how valid is it to alter the performance to make it a better experience? [snip]


Demian,

There is no way that an audio system can reproduce those components of the live performance that are non-auditive, including, as you say, the dinner before and the nitecap after. It stands to reason that any attempt to build an audio system that comes close to such a life experience is utterly futile.

I have argued before that we should stop to tell each other that 'it doesn't sound like the life experience'. Actually, it *could* SOUND like the life experience, but it is not PERCEIVED as the life experience.

Our goal should be to build audio systems that are as transparent as possible, that do not take anything away or add anything to whatever is on the source. We are anyway at the mercy of the final mixing engineer, no?

Jan Didden
 
Re: Re: Re: Re: Re: Re: Re: tone controls

Edmond Stuart said:


Sure, but how?

The only thing I can tell you is that I was present during that "correction". The speed was controlled by external box, connected through cable and connector. I do not know if he regulated frequency or voltage. It is not important though. The only important thing is he changed speed for a while to get her voice to the tone.
 
CG said:


The word that comes to mind is plagiarism. That's where you don't give credit to the original author for their work and leave the impression that it is your own.

What's so hard about saying, "This was inspired by the work of (fill in the blank)"?

In this case, even John Curl has gone on record saying that he was inspired by Charles Hansen's work.

It is not necessary the case.
For example, one fellow engineer seeing schematic of my Pyramid tube amp said that it is a modification of an old Altec amp used in cinema theaters. Well, if I would not implement direct coupling between tubes and increased gain of drivers somebody would say it is a modification of Williamson amp. The problem is, there are infinite number of ways of designing suboptimal electronics, nut while designing optimal electronics many developers tend to come to very similar results.
 
lumanauw said:
Yesterday we did a real comparison between live performance and reproduction sound. To know what the differences are, and what to (or could) be expected from reproduction sound.
Fortunate enough to have a descent Hi-End system (the room+equipment) whose owner support this comparison. Fortunate enough to get a good live performers. To get many panelist.
We try to play and compare same song from CD, LP and live performance.
Preparation :


lumanauw said:
live performance equipment


lumanauw said:
live performance running


lumanauw said:
Some of the panelist


So, where are results?
 
syn08 said:

Example: a recent article in the AES journal proved beyond any doubt that there is absolutely no difference (measured or ABX) between SACD and classic CD. If there is any difference, it then comes from the original recording quality which may be better if SACD was the targeted media. Otherwise said, don't bother to buy old records on SACD. It won't make a shred of a difference.

There's just no way to politely phrase any comment on that result. They very seriously need to get their heads examined. There is very definitely poop inside for the folks who conducted that test.

"Audibility of a CD-Standard A/DA/A Loop Inserted into High-Resolution Audio Playback
JAES Volume 55 Issue 9 pp. 775-779; September 2007
Authors: Meyer, E. Brad; Moran, David R.
Affiliation: Boston Audio Society, Lincoln, MA, USA


They D/A the SACD output, then re-sampled to the CD format and D/A again. There was no difference in the ABX tests between the two analog outputs. Unfortunately I can't post the whole article, it's copyrighted.


idiots. idiots. idiots.

Pardon Me gentlemen. I just got off the phone after trying to explain to someone that there are NOT two candidates. There are none.
 
Wavebourn said:

..........
The problem is, there are infinite number of ways of designing suboptimal electronics, nut while designing optimal electronics many developers tend to come to very similar results.

Even if your gradient search manages to avoid a local 'dimple', you're implicitly stating that you've found the perfect objective function. So exactly what weighting should I give that 7th harmonic, montonicity, etc.... Please do share.

And heaven forfend that the objective function should be in the least bit subjective.......
 
KBK said:


There's just no way to politely phrase any comment on that result. They very seriously need to get their heads examined. There is very definitely poop inside for the folks who conducted that test.

"Audibility of a CD-Standard A/DA/A Loop Inserted into High-Resolution Audio Playback
JAES Volume 55 Issue 9 pp. 775-779; September 2007
Authors: Meyer, E. Brad; Moran, David R.
Affiliation: Boston Audio Society, Lincoln, MA, USA


They D/A the SACD output, then re-sampled to the CD format and D/A again. There was no difference in the ABX tests between the two analog outputs. Unfortunately I can't post the whole article, it's copyrighted.


idiots. idiots. idiots.

Pardon Me gentlemen. I just got off the phone after trying to explain to someone that there are NOT two candidates. There are none.

I assume you've read the article and disagree with the conclusion. If so, then you are an AES member and you are welcomed to post your rants on the AES forum (you need to be a member to post). You may have your chance to get a response from the authors themselves! But you better bring some arguments to the table, the language that you just used above won't do anything but disqualify you.

Alternatively, you may live in your own beliefs. Nothing wrong with that, but then don't be surprised when your own bull gets gored.
 
pmkap said:


Even if your gradient search manages to avoid a local 'dimple', you're implicitly stating that you've found the perfect objective function. So exactly what weighting should I give that 7th harmonic, montonicity, etc.... Please do share.

And heaven forfend that the objective function should be in the least bit subjective.......

Sorry, English is not my native language.
Can you translate please on English For Foreigners?
 
CG said:
In this case, even John Curl has gone on record saying that he was inspired by Charles Hansen's work.

Sort of. I have repeatedly stated in these forums and printed interviews that the biggest influence in my circuit designs was when John Curl published the schematics of the original Mark Levinson amps and preamps in The Audio Amateur way back around 1977. (He did this because Mark Levinson screwed him on the royalty payments.)

Since then, Mr. Curl has been inspired by my circuits to make some zero feedback designs (such as the Blowtorch), although his commercial circuits (eg, for Parasound) still use feedback. So my influence on his thinking has been rather limited. (I have however, also shared some information on various parts that has been mildly helpful to him.)

Bottom line -- he is the master, I am the apprentice.

jacco vermeulen said:
Why not just ask Mr Milan Moamps himself ?

Several subsequent posters seemed to have missed Jacco's irony here. Can it really be a coincidence that "Moamps" has been reading this thread for over 2 years, and then he just happens to make a preamp that is nearly identical to the Blowtorch?

Of course not!

Clearly Moamps has taken many, many ideas from John Curl. And I completely agree that to do so without offering any credit or attribution is (at best) atrocious manners.
 
Charles Hansen said:
Since then, Mr. Curl has been inspired by my circuits to make some zero feedback designs (such as the Blowtorch), although his commercial circuits (eg, for Parasound) still use feedback. So my influence on his thinking has been rather limited. (I have however, also shared some information on various parts that has been mildly helpful to him.)

I should have been more specific here, in fairness to all. It was all clearly stated (much) earlier in this thread. Time to be quiet again...

mea culpa
 
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