John Curl's Blowtorch preamplifier part II

[gpapag]

Originally Posted by DF96

Not sure I agree. There is a view that maths is discovered by us. We may invent the symbols, the language of maths, but the concepts already existed before we knew about them. On this view, reality and maths have a common origin. I can't say more, as it would be seriously OT!

Originally Posted by Ken Newton

I can essentially agree with that. Although, I would say that reality has rules which define existence in our universe. Material and energies in this universe inter-relate according to such rules. So, in that sense, yes, math coexists as the language which precisley describes these rules. We observe phenomena and search for the rules, the math, which are governing it. The important distinction is that the history of science is filled with math which we though completely desribed some rule of existance, only to have further observation reveal our understanding to have been incomplete or even faulty. In those cases, the math is revised to reflect reality, the reality isn't revised to reflect the math. This is more than a distinction without a difference.

Originally Posted by abraxalito

Nope that's the wrong way around. We observe patterns in the behaviour of nature and infer that there are rules - however the rules are an artifact of thinking. Nature just has habits which we observe. We use math to model those habits and our models evolve over time. Math no more governs reality than grammar governs what people write in a natural language.

You are scratcing the core of a long standing –still hot- debate among the supporters and the opponents of Plato’s expressed ideas over “knowledge”. Don’t expect to reach a consensus in this lifetime (unless you know that already )

George

[SY]

Originally Posted by Jakob2

Sorry for the inconvenience, but i thought i did post some descriptions of these tests over the years?!

Well, now I'm thoroughly confused. You published them, you didn't publish them, now you published them. When you figure out if and where where you've published detailed descriptions of test protocols, methods, controls, data, results, and analysis, I'll be interested to read them.

[gk7]

I found Jakob2s answer clear enough. Why are you confused ?

[SY]

Perhaps I'm not nearly as smart as you. I can't figure out which answer is the actual one.

[jneutron]

Originally Posted by Jakob2

At that time i read the comments of the anonymous professor in the Audio Critic, but had not read (and have still not) Hawksford´s article and afair the anonymous got at least two things wrong in his rather short statement.

The funny thing is, that according to jneutrons arguments, the anonymous professor might have missed a lot more.

So it´s time to read the original papers.

My take on the prof is that he wrote his comments while emotionally charged. As such, I am guessing that he didn't feel the need to elaborate past a certain point due to the obvious nature of the errors. I am also guessing that the prof was exceedingly unhappy that such an article was printed within the popular press without the benefit of peer review. Peer review may have turned up the failure to consider internal inductance that I discuss.

To me, neglecting the internal inductance is a clear and obvious test violation, but since I live and breath this kind of test stuff, my experience may be the only reason I spotted it.

When I first encountered his published waveform, I was shocked that it was an exact duplicate of one I dealt with a few years prior. The upshot of my analysis and fix was that the diode being tested did not have a Trr of 5 milliseconds, but that the 250 micro-ohm CVR was collapsing it's field and the test system was picking up the flux of the CVR. Since the CVR was a set of 11 copper plates 4 inches by 4 inches by about 100 mils, I simply had the tech run a wire down the geometric center of the resistor...that eliminated the flux trapping and solved the problem. (pic attached, it's fuzzy cause it's through a 1/4 inch lexan blast shield..)

It did not require I define some new entity via planar wave field penetration to describe the "new phenomena", just an understanding of ampere's and faraday's law and how they can bite ya if you're not careful.

Cheers, jn

ps. The article initially cited was published in stereophile october 1995, starting on page 53, ending on page 69. The 70 page document mentioned by John Curl was called a Unification document, comprised of many "tracks", and on my computer it comes out as 88 pages. Page 70 is where the conclusions begin, at the bottom...and the following pages are appendicies, test diagrams, and matlab code he generated for his simulations. The unification doc was a series of publications in HFN/RR, starting in may of 86.

[DF96]

People always seem to be surprised, and cry "distortion!", when the waveform at the output of a filter is different from the (non-sinusoidal) waveform at the input. Did they expect just a change in amplitude and a bit of time delay? Hawksford carefully navigated around this particular mistake, by admitting that the system was linear and so could not generate new frequencies, but then threw a bone to the cable freaks by muttering about grain boundaries etc. Trying to have his cake and eat it?

Maybe someone on here with the necessary software to hand could publish the spectrum of a short unprocessed zero-starting (and finishing) tone burst, so that others can see what a wide band it covers. To make life easy, you could assume a burst repeat frequency which is an integer sub-multiple of the tone frequency. Then put it through a first order low pass filter with rolloff well above the tone frequency, to exhibit the 'distortion and time smearing' which appears at the leading and trailing edges. I think this would be educational for those who have never actually calculated a Fourier series themselves.

[abraxalito]

@DF96 - download Audacity (its free) and you could probably do it yourself. I know I've created a toneburst with it in the past, and it has the necessary FFT capability.

[Joshua_G]

Originally Posted by abraxalito

Nope that's the wrong way around. We observe patterns in the behaviour of nature and infer that there are rules - however the rules are an artifact of thinking. Nature just has habits which we observe. We use math to model those habits and our models evolve over time. Math no more governs reality than grammar governs what people write in a natural language.

Indeed.

[scott wurcer]

Originally Posted by Jakob2

Yes, i remember that although i have never seen some official presentation of data.
Under the question you have quoted, the exclusion of socalled outliers were indeed highly questionable.

I scored 100% without even listening to the music at an AES demonstration by listening for the A to B and B to A clicks.

[scott wurcer]

Originally Posted by DF96

People always seem to be surprised, and cry "distortion!", when the waveform at the output of a filter is different from the (non-sinusoidal) waveform at the input.

Do you think folks will ever stop trying to PROVE digital audio is flawed by using waveforms that violate the sampling theorem?