That's a nice article.
There are also some good discussions about currents and noise in conductors in Dunn, Gateways into Electronics.
I hadn't seen that Hawksford one. But it would sure be nice if he used an example from real life and put some numbers to his claims. That however would be hard work, and probably quite revealing of the minute levels if measurable at all, or worse, his inability to apply all of the EM theory he throws down.
Another guy who did some cable investigations was Richard Greiner, in Audio (magazine). IIRC he ends up concluding that amplifiers should be close to loudspeakers and any needed remoting of signals be done via line-level interconnects.
Reminds me of when my colleague Harland did an entire EM exam writing with his right hand and using his left hand for the right-hand rule.The way your thumb points. Duh.
Or in my sinister case, the opposite.
Sigh...
Delve into the technical aspects of his discussion, many flaws.
Note within that he did a bait and switch on the wire he used for his actual test. As John Curl informed me, MH was unable to see the effect he wanted using copper wire, so substituted magnetic steel wire. He did not consider the magnetic permeability of the steel in his equations.
The internal inductance of a conductor is 15nH per foot times the magnetic permeability of the conductor. (edit..relative magnetic permeability)
Also, he had no understanding of the difficulties of measurement involved when testing very low impedance circuits.
Basically, he played with a circuit using flawed analysis. (btw, the exponential skin depth equation is useless for round conductors at this scale, it is ideal only for planar waves impinging on flat conductive surfaces, bessels are needed for the round conductors. Once he obtained waveforms which were consistent with his conclusions, he published.
No recheck, no peers, nothing.
btw, look at his diagram for e-field with the "river along the banks" explanation... only one wire has that, the other is reversed..
John
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Well if anyone wants to try an almost simple experiment take an ordinary audio interconnect cord pass a signal level of 10 millivolts at 3,000 hertz through it to a termination of 1,000,000 ohms. Measure across the cable using a high impedance low noise amplifier. (Not exactly easy!) Then reverse the cable and measure again. Do this about five times and record your results.
Imagine working with colleagues where half of them need to use the left hand rule, and half use the right hand rule..
John
"Cables and the Amp/Speaker Interface"
"Amplifier Loudspeaker Interfacing" AES May 1980
Discussed here in 2009, #12 zip cord is the perfect solution if I remember correctly (price and performance).
Interesting. I have been intrigued for some time that the expression for space-charge smoothed shot noise in valves seems to look more like thermal noise, as the electron charge q disappears from the formula and kT appears instead. The article gives another example where this connection appears. It may be that we are on the boundary between statistical mechanics and thermodynamics: when we talk of the particles we get shot noise; when we talk of thermal fluctuations we get Johnson noise. Shot noise will still occur with uncorrelated discrete charge carriers when the randomness is not thermal in origin; similarly Johnson noise will still occur whether charge is discrete or not. It is interesting that when both effects are in play we only get one lot of noise rather than having to add the two together.
I was always weak at solid-state physics when I studied it 40 years ago, and now I'm rusty too! I am not in a position to judge their derivation of resistor thermal noise. It may be fine, or it may have sneaked in the result already encapsulated in the Einstein relation for diffusion constant. In either case it seems to me that their derivation has to use more physics than the original transmission line derivation - although the latter always looked to me to be 'a bit too clever'.
If they are right MH fuzzy distortion gets knocked on the head, by another method. His postulated shot noise due to discrete charge is just thermal noise due to gate resistance; nothing new there. Its always nice to have a new way of demolishing error!
And.................
Why has no one else discovered directional cable other than Audiophiles; maybe I have answered my question
An-dextrous. That is, not right handed. (Latin for ambidextrous is "both right handed")
Right. But isn't the real issue not so much whether MH was right or wrong, but whether or not anybody can actually hear any difference in speaker cables of typical length and of adequate gauge? If they can, then there must be some underlying physical basis for it (whether or not MH has it right), and if not, it doesn't matter if there is some theoretical basis, be it for transmission lines or any other known physical effects. If you can't hear it, it doesn't matter.
My understanding is that test results of people trying to hear differences in speaker cables give random results, meaning that no effect can be heard.
Modern students would expect that sort of information to be on a printed handout (which they would promptly lose, and demand another copy). You can't expect them to make notes in a lecture; when else are they going to find time to catch up on their sleep, or text their friends, or make rude online remarks about their teacher?
Oh, my students (within EE and Nanoengineering--which is glorified chemE) are generally quite polite. They're screwed pretty well by our university system so I can certainly appreciate their frustration. Then again, I'm one of their "nicer" albeit harder TA's usually, inasmuch as I want them to learn, and don't give away answers without pushing students to grow. So I pretty well train everyone that whining gets you the door versus asking courteously and clearly.
It's a lazy cop out to call students wanting everything handed to them. Makes you sound like the fifth Yorkshireman from the Monty Python sketch.
It's a lazy cop out to call students wanting everything handed to them. Makes you sound like the fifth Yorkshireman from the Monty Python sketch.
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