Not anymore. I just learned he passed away last year, just after completing his capacitor article for Linear Audio. Another one of audio's great personalities gone.
Jan
I did say why - see an earlier post. He seems to believe that line characteristic impedance and reflection coefficient are real numbers. The former is generally only true for RF lines and specially-conditioned audio lines (e.g. telephone analogue trunk lines), and the latter is rarely true except for correctly terminated RF lines.jneutron said:
I'm sure he has access to the same textbooks as me. If they haven't helped him then I doubt if I could.
It was his understanding of theory I questioned. No equipment needed. Of course, having misunderstood the theory he might then have misunderstood the results of his tests. If you put someone on a pedestal then I suppose you have to accuse someone else who seeks to correct him of being "an internet guru wannabe". It is simpler than engaging with the point at issue.jneutron said:
Who is davis? Have I read his article? If I seek an authority on these matters I usually go to one of the serious textbooks such as Jackson or Ramo, Whinnery and van Duzer.
Fred Davis. His JAES article shows a different approach than John is happy with. Ditto Dick Greiner's papers, and he was indeed an EE professor who taught EM theory. I think Jan might have linked the Davis paper earlier in this thread.
edit: Here's the cites, someone posted a link to the Davis paper but I can't immediately find it.
http://www.diyaudio.com/forums/everything-else/193100-speaker-cable-myths-facts.html#post2648578
edit edit: I've attached a pdf of the Davis paper.
edit: Here's the cites, someone posted a link to the Davis paper but I can't immediately find it.
http://www.diyaudio.com/forums/everything-else/193100-speaker-cable-myths-facts.html#post2648578
edit edit: I've attached a pdf of the Davis paper.
Try cable lifters in double blind listening comparison and come back. It'll be better than this "mine is bigger" contest you are trying to win. 🙄
IMO one of the better texts concerning the propagation of EM energy as it applies to short lines moved slowly is an undergraduate text Vibrations and Waves in Physics Iain G Main ISBN 0521 26124. Not because it covers TL theory in any detail, but because it elegantly explains the very concept of energy exchange between forms in general which leads to the phenomenum of propagation. Much of the text describes mechanical systems of various sorts for convenience, but similar principles apply to EM waves, including TLs.
Perhaps its easier to visualise systems such as strings or springs which are short being moved slowly then acting as one body without any propagation, I don't know. But there isn't necessarily any meaningful wave propagation unless the system supports it, and that is where we are at with short cables at audio frequencies. Bateman's mistake, and others here too.
DF96 summed it up well by saying that a single LCR cell models audio cables at audio frequencies well. That is to say the elemental cell, in the limit as length tends to zero, has already been reached. None of the physics which relies on further reduction applies in this system, it is already elemental. It's a conceptual mistake to apply TL theory results.
Perhaps its easier to visualise systems such as strings or springs which are short being moved slowly then acting as one body without any propagation, I don't know. But there isn't necessarily any meaningful wave propagation unless the system supports it, and that is where we are at with short cables at audio frequencies. Bateman's mistake, and others here too.
DF96 summed it up well by saying that a single LCR cell models audio cables at audio frequencies well. That is to say the elemental cell, in the limit as length tends to zero, has already been reached. None of the physics which relies on further reduction applies in this system, it is already elemental. It's a conceptual mistake to apply TL theory results.
Twisted pair indoor telephone wire has characteristic impedance of around 100 ohms.
!0 parallel pairs gives around 10 ohms characteristic impedance, and 20 parallel pairs around 5 ohms, and both contain plenty of copper.
I have used both types for short and long cable runs.
In all cases (Naim excepted) the subjective result is substantially clearer and cleaner in room sound compared to typical fig-8, and especially Monster Cable type Fig-8.
Digital sources combined with high bandwidth amplification means appreciable level of HF/RF presented to the speaker cable.
Provided that the load loudspeaker exhibits flat HF impedance characteristic (loudspeaker end zobel required), maximal return loss (minimal reflected power) is achieved.
It is a mistake to consider only 20Hz-20kHz bandwidth.
Dan.
!0 parallel pairs gives around 10 ohms characteristic impedance, and 20 parallel pairs around 5 ohms, and both contain plenty of copper.
I have used both types for short and long cable runs.
In all cases (Naim excepted) the subjective result is substantially clearer and cleaner in room sound compared to typical fig-8, and especially Monster Cable type Fig-8.
Digital sources combined with high bandwidth amplification means appreciable level of HF/RF presented to the speaker cable.
Provided that the load loudspeaker exhibits flat HF impedance characteristic (loudspeaker end zobel required), maximal return loss (minimal reflected power) is achieved.
It is a mistake to consider only 20Hz-20kHz bandwidth.
Dan.
Last edited:
Great - if you can keep them separate you'll reduce inductance by a factor of 10 and reduce resistance by a factor of 10 from whatever a single pair presents. And increase capacitance by a factor of 10. It's such things which might produce any real effect, rather than TL rf impedance or 'matching' effects per se. Increased C might act upon amp stability at rf and be audible for better or worse, as you might have noted, but audibility to me of associated audioband timing changes is usually very subtle at best based on my own experience, so who knows.
Yes. What do you consider necessary ?Max Headroom said:
I think John has already weighed in on his opinion about audibility. Or the high non-likelihood. 😀
And what I'm saying is, other than applying the theory into the actual practice to confirm, what more is there to post about?
I don't know, anything anyone wants besides politics and religion?
You don't need to participate if it pains you.
JN might say that he has. I might say the theory is meaningless and tests/sims merely demonstrate a backwater of established conventional physics which is unremarkable except that step/risetime response seems fairly unexplored in the context of speaker cables. Seems interesting enough to me, best thing going IMO.
Scott,
Well, I always make sure my left and right channel op amps are lined up the same way!! Makes sense to do the same with speaker cable, right? 😀
Well, I always make sure my left and right channel op amps are lined up the same way!! Makes sense to do the same with speaker cable, right? 😀
Scientific process would call for the investigation of observed event and in this case it would be what the listener perceived when using speaker cable lifters. Logically, the cause would need to be isolated. It turned out from double blind test that the cable lifters didn't make audible difference and it was all in the listener's mind. Now, should one delve into what's going on in the mind of the listener or what's going on with the speaker cable?
Most modern well regarded amplifiers have response out to 100kHz or so, some lower, some higher.
Digital stage output filtering reduces but does not totally remove ultrasonic content.
I am saying that it makes engineering sense to ensure that the cable and load combination is non reflective in order to reduce/eliminate return energy.
A zobel at the amplifier output is useful but not the total solution.
10 pair or 20 pair telephone cable is cheap and easily available...the only downside is the terminating time required.
Subjectively ime, the benefit of 10 or 20 pair is more solid/deeper bass, cleaner mids/vocals, and clean highs without the ''sizzle/spit'' that is all too common, and higher perceiver power/headroom.
Cooler amplifier running is another benefit.
Part of these benefits are due to low DCR, but the low loop inductance is the key.
As I have stated, Naim amplifiers will oscillate, but in practice over 25 years or so I have not had any detrimental effects with any other amplifiers.
Before arguing why the above observations cannot be so, please try it for yourselves.
Dan.
PS - I currently don't have the gear/setup to measure/sweep typical lengths of 10/20 pair cable.....anybody willing/able to do so ?.
Last edited:
Wow!
"Cooler amplifier running is another benefit."
You really do not understand audio engineering at all, do you?
"Cooler amplifier running is another benefit."
You really do not understand audio engineering at all, do you?
Before arguing why the above observations cannot be so, please try it for yourselves.
Dan.
- Status
- Not open for further replies.