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In Reply to: Frostbite Falls Audio inc posted by tomservo on April 17, 2007 at 12:15:59:
Hi Tom,I can't tell you how certain I used to be that "directionality" in cables was utter hogwash. I can now confidently state that some cables, connecting some equipment, sound distinctly different when reversed. I've found it especially true with solid conductor interconnects. I offer the statement sans mechanism. However, since I built numerous cable samples myself, I'm convinced that the variable which determines the cable's "direction" is which direction the wire comes off the spool.
One structure I used was two "hots" and two "colds" spaced out enough to give around a 300 ohm impedance. To test directionality I carefully built two identical cables differing only in that one had all four wires pulled off the spool in the same direction, the other had one in either direction in both the hot and cold sides. The result was gratifying as it sort of 'made sense'. The one made with all the wires the same was quite noticeably directional being rather bright in one direction and mellow in the other. The mixed cable sounded the same in either direction and was in the middle in brightness.
That was about 15 years ago and my goal was to empirically improve my sound so I built up cables for both my systems, connected them in the 'mellow' direction and use them to this day. While routine measurements did not reveal any difference in the directions, it was clearly audible so I wasn't measuring the right things. I have some suspicions about the underlying mechanisms but it's bootless to trot them out without supporting data. Maybe another day.
I've really enjoyed your posts and they have engendered an enhanced, albeit virtual, appreciation of speaker design. I especially liked the discussion concerning the use of electrical analogs to represent acoustical and mechanical characteristics.
I do chaff at the notion that propagation time on a PCB has much to do with the conductors as I reckon that it's dominated by the dielectric. The conductors mostly determine the impedance. Also I was surprised that you took issue with May's quote concerning energy flow in cables as it sounds about right to me. How does modeling software update it? If you do model the fields on a cable using some of the Ansoft stuff, or FEMM if you're on a budget, you'll see what her quote describes. But you won't see directionality because it's mechanisms must be understood and their behavior specifically included in the model first.
Follow Ups:
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No, really...
The threshold for disproving something is higher than the threshold for saying it, which is a recipe for the accumulation of bullshit - Softky
The paragraphs (from a magazine article in 1983) I quoted from were to show both that the controversy regarding directionality is still going on (in fact it resurfaced again late last year in Hi Fi News and was then taken up by New Scientist in January 2007) AND as an example of how people who have not experienced certain things (for example - directionality and cryogenic/freezing effects) then they are unable to understand what other people are talking about but people who HAVE experienced certain things recognise immediately what others are describing.The words of the magazine article I quoted from are not mine, however I salute the courage of the person writing them - and, they are still relevant today - 24 years later.
Regards,
May Belt.
a
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