miklos, John quite properly withholds at least some details since, among other things, he still may make these. And there are "amateurs" who just want to copy the design and make it, whether they understand it or not.
But there has been more than ample discussion of the salient features, including schematics of related products showing some of the topological approaches, and including some aspects of the power supplies. The problem is you actually have to read the rather long thread
Actually I read about 20,000 of the replies, but thank you for answering instead of John Curl.
John had stated this, basically, before, when people kept hectoring him for a schematic, so I thought I would do him the favor of a paraphrase. What I could have made more clear is that some people might well attempt to create business of copycat blowtorch preamps, not merely attempt construction of one for their edification and personal use.
I was reminded of a character I knew many years ago, ironically also one who shared the initials, who enthusiastically copied everyone, and about whom we used to joke that he would be a candidate for authorship of one of the "slim volumes" books. That category includes such imaginary titles as Ethical Business Practices, by Kenneth Lay (the Enron guy). In this JC's case (emphatically not John Curl) the title of the slim volume would be My Original Electronic Designs.
Thank you, bcarso. My biggest concern, these days, is to take 'responsibility' for the amateurs who would try to make it. I do try to help with the Levinson JC-2 or JC-3, but THOSE products are buildable by amateurs, because they are more 'forgiving' as to parts selection. I just went through the first 80 pages of part 1. Almost everything is there, IF you are expert enough. If you are not, well it is too much trouble, anyway.
One guy attacked me for making an 'obvious' and insignificant design, yet he started making a clone, that was laughably similar to the Blowtorch. That is what I try to avoid, as well.
One guy attacked me for making an 'obvious' and insignificant design, yet he started making a clone, that was laughably similar to the Blowtorch. That is what I try to avoid, as well.
Exactly John. One is joined at the hip to one's designs no matter how long ago they saw the light of day. And you are considered a bad person if you don't solve all of anyone's problems.
I like the ones who come along and say one's circuit simply doesn't work. Particularly when this judgment is passed based on the results of simulations!
As you say, for those sufficiently sophisticated, the information is there in the beginning of the thread.
John, I have found that the unethical will never pay cash, for legal reasons of course.
They will offer to "trade a pair of speakers", or "I will just copy it?
Cheers.
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A shield would only be affective if the rfi was field-coupled. If it were direct-coupled then a ferrite around the cord would work... for both - just place it close to the equipment. --RNM
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Actually all that dirt mostly goes through ground loops due to unbalanced interconnects. In professional audio equipment it is non-issue. However, so called semi-professional gear with quasi-balanced, or electronically-balanced ins and outs picks up this dirt, but it is because of flaws of implementation. But if to adopt this approach to consumer audio equipment nobody will buy that multidollar cables.
Just one illustration from the article:
The gray curve is a graph from the output of an amp with 0.05% THD, mainly xover. It's very hard to see ANY irregularity in the waveform.
However, when you weight the harmonics with Ian's new method and add them back in you get the black waveform and you can clearly see the nonlinearity. This would correspond much better to the sensitivity of the ear for this type of distortion.
This is from a simulation but actual measurements show similar results.
jan
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Isn't the local phrase overthere "Klusserdeklusserdeklus" ?
(oh no, the evil one who makes me do chores is approaching, so that's what the freebee makita lxt box was for)
I find it almost impossible to get anything new from these distortion discussions, if we have to have double blind tests as the ONLY criterion for the validity of actually detecting distortion in our audio equipment, implying that we are a bunch of arbitrary subjectivists, who ONLY are affected by labels, price, or perhaps construction.
Distortion recognition and individual harmonic weighting have been known for at least 75 years, refined over the decades.
Jan I think that your new test could lead to something important.
It is only when we discuss something like this distortion 'revealing' approach, we get the double blind argument that virtually everything sounds the same. At least components with good frequency response, and distortion below perhaps 0.5% have been 'proven' to be virtually identical to each other. This does NOT fit my reality, any more than any wine of a certain type and alcoholic content tastes the same, and only the label and the price make the difference.
Distortion recognition and individual harmonic weighting have been known for at least 75 years, refined over the decades.
Jan I think that your new test could lead to something important.
It is only when we discuss something like this distortion 'revealing' approach, we get the double blind argument that virtually everything sounds the same. At least components with good frequency response, and distortion below perhaps 0.5% have been 'proven' to be virtually identical to each other. This does NOT fit my reality, any more than any wine of a certain type and alcoholic content tastes the same, and only the label and the price make the difference.
Wrt to our discussion of the ear´s sensitivity to "phase issues" i´d once again highly recommend jj´s ppts at the aes, in this case for example:
http://www.aes.org/sections/pnw/ppt/jj/fund_of_hearing.ppt
it is a good introduction and if someone wants to explore certain aspects a bit more there are a lot of keywords for further search.
The other material is located on this site:
PowerPoint Presentations from recent (or not so recent) meetings.
@ dimitri,
the funny thing in the russ andrews case was, that the hidden expert requested explicit proof for a long established (or well known) fact, i.e. that an impedance mistermination causes partly reflection of conducted rfi .
http://www.aes.org/sections/pnw/ppt/jj/fund_of_hearing.ppt
it is a good introduction and if someone wants to explore certain aspects a bit more there are a lot of keywords for further search.
The other material is located on this site:
PowerPoint Presentations from recent (or not so recent) meetings.
@ dimitri,
the funny thing in the russ andrews case was, that the hidden expert requested explicit proof for a long established (or well known) fact, i.e. that an impedance mistermination causes partly reflection of conducted rfi .
Jan, I would like to point out that what you are showing is, partially, what we see from the 'distortion' output on a scope, WITHOUT the fundamental frequency. We get the same information by using a 2 channel scope, put the signal up top, and the distortion residual on bottom. IF we could take a THD meter and put a 12dB/octave boost as the distortion weighting, we would most probably get a very good correlation to Geddes or earlier work.
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