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Re: Question? Since you mention capacitance and inductance when speaking

bjh: "" are we to infer that those are the only properties that have relevance to what we hear?""
The only things important are R L and C for bulk cables.

UNFORTUNATELY, all three are rather complex entities.

R and L vary with freq, skin effect. C is also, but it has many issues like soakage as stuff. So the quality of the dielectric is a big mush..until test capability is able to see the non linearity vs time for capacitors, the whole da thing is gonna be nuttin but hand waving. The basic stuff that was done years ago on caps, like that marshall article were very good, but don't go into real qualitative analysis, just point out the diff.

bjh: ""Also, even in the case of capacitance and inductance should we only be concerned with the absolute values of these properties (for that matter, in the case of cables, does the concept of absolute values even make sense?), or are there other considerations, e.g. a concept such as quality perhaps?""
RLC are all relative, so abs val is to be considered with respect to the load that is being driven.. L and C multiply to a constant, this constant changes with dielectric, which also can be frequency dependent.. C has a quality issue as well.

bjh:
""Finally, when you say "You may be unable to understand what or how to measure, that is your limitation, not mine", are you implying that you possess definitive knowledge to associate objective measurements and/or other artifacts with subjective performance for cables?""

It's easy to calculate out how the R, L, and C will cause changes in the waveforms, both for ITD and IID from a simple linear vantage. More complex issues are related to power dissipation into the cable resistance feeding a branch load, with that weird A2 plus B2 term, the 2AB..and, I'm wrestling also with a concept called inductive shedding, the ability of a hf waveform to zero out the inductive energy storage of a lf waveform, both via skin decimation, or flat out current squared terms. Something doesn't seem right in the energy balance, so says my gut. Working out those equations currently.

The real problem stems from determining the level of audibility of those shifts. We are sensitive to those parameters depending on where the image we wish to create is. I've seen no real research which addresses our sensitivity to those parameters in a differential manner. Most of the research is either shift one for threshold detection, or shift one with the other constant. But not really shifting both in configurations which are real world stimulus.

It is easy to measure how the cable parameters will shift the information. It requires some rather hairy, low inductance special resistors and the ability to detect small temporal shifts for reactance, some small amplitude shifts for resistance. But that technology is easily within grasp.

The real problem stems from understanding how we perceive the shifts. There, unfortunately, little work is evident in the high end world with respect to how we image.

bjh: ""If so can we expect publication anytime soon?""

I post a lot of this stuff on the forums, but absolutely nobody seems interested in persuing it. As I have a life, a job, and a honeydo list of several hundred (it seems) items, I would not be publishing anytime soon.

Got the kitchen functional now, so at least I can begin the work of setting up my basement lab in the next year or so. It's suprising how slow the detail work at the end of the job is.

Cheers, John


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  • Re: Question? Since you mention capacitance and inductance when speaking - jneutron 12:22:31 04/04/06 (2)
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