Directional speaker cables - switching direction

One way to find out for sure, flip your 10 AWG Blue Jeans Cables end for end and listen for any difference.

And then flip them back and forth at least two and preferably three or more times, not only to verify that your perceptions are consistent, but that the perceived difference (if any) is not the result of an extraneous variable (for example, changes in contact integrity, changes in AC line voltage or noise conditions, changes in room temperature or humidity, etc). Re humidity, see the post by Georgelofi dated 6-17-14 in this thread.

IMO, the less explicable a perceived difference is, the more thorough the assessment needs to be, before concluding that the difference has been attributed to the right thing.

Brf makes a good point, btw, that many shielded cables, especially interconnects, are designed asymmetrically and can certainly be expected to be directional. In those cases the end at which the shield is connected should generally be connected to the component which drives the cable.

Regards,
-- Al

Thanks, Jim.

One more possible extraneous variable I would keep in mind, adding to my earlier list, is the equipment being in unequal states of warmup during the different parts of the comparison.

Or the possibility that even if the system is shut down briefly enough to avoid a significant change in warmup conditions while the cable directions are being changed, that just the fact that power has been cycled may somehow affect the amplifier or other components. Why might that be? I don't know, but the possibility seems to me to be no more unlikely than the possibility that changing the direction of a symmetrically designed cable would affect the sound.

As I see it there's no substitute for going back and forth multiple times during the assessment, before reaching (and/or promulgating) any conclusions, rather than just flipping once.

Best regards,
-- Al

12-18-14: Geoffkait
I also do not happen to think the dielectric material affects the velocity of the signal. As I already said I think the velocity of the signal is fixed (constant) for a given medium, I.e., copper or whatever.

That is not true, Geoff. What Kijanki said is correct. For starters, see this Wikipedia writeup. Many other references can be found which will further confirm this. Widely varying propagation velocity specifications for various cables utilizing copper conductors can also be found.

12-18-14: Jea48
An experiment for those of you that use a CD transport and a separate DAC. If your digital coax cable has a solid core center conductor try this experiment. First listen to a good sounding CD with a strong female voice. Find a particular track you like and listen to it closely a few times. Now flip the digital cable end for end and then listen again. One good CD that comes to mind is, Etta James "Love Songs" track 1) "At Last". Also try a good sounding CD with a piano solo. Post back your results.

I don't use a separate DAC, but FWIW I can hypothesize a reason why a symmetrically designed digital cable may sound different, under some circumstances, depending on the direction in which it is connected. My hypothesis, though, has nothing to do with the wire itself having directional properties, and says nothing about the possibility that a symmetrically designed cable conducting analog signals may be have directional properties.

The connection between a digital cable and its connectors will have an impedance discontinuity and inaccuracy to some non-zero degree, which will result, to some non-zero degree, in some fraction of the amplitudes of whatever RF frequencies it may be asked to conduct being reflected back toward the source of the signal. I would expect the magnitude and character of that impedance discontinuity to not be totally identical at the two ends of the cable, due to small differences in solder application, crimping, etc., and perhaps even to dimensional tolerances in the connector.

Also, the output impedance of the component driving the cable and the input impedance of the component receiving the signal will not be precisely accurate.

Therefore the impedance mismatches between the cable and each of the connected components will differ depending on which end is connected where. And digital audio signals contain frequency components extending well into the RF region, up to at least tens of MHz. (Keep in mind that the risetimes and falltimes of the signal contain significant frequency components that are much higher than the clock rate and the data rate).

Depending on these factors, and also on the length of the cable, and also on the data rate that is being transmitted, the resulting reflections may very conceivably affect waveform quality at or near the mid-point of positive-going and negative-going transitions of the signal, those transition mid-points being what the receiving circuitry responds to. Degradation of those parts of the waveform will affect jitter, and therefore potentially sonics, to some degree. And that potential degradation will, per the earlier parts of this explanation, be affected by which connector is mated with which component. It will also be affected by whether the more significant of the two potential mismatches is at the receiving end or the transmitting end, and by the degree of impedance mismatch at both ends (which will affect how many back and forth re-reflections occur until their amplitude becomes insignificant).

See this paper for further discussion of the effects of impedance mismatches and waveform reflections on jitter, although the paper does not address the question of directionality.

If all of that sounds a bit far-fetched, IMO it is less farfetched than an assertion that wires themselves have directional properties to an audibly significant degree.

Best regards,
-- Al

P.S: My post just above was written before Jim's post immediately above it appeared. I haven't yet read the Stereophile article he linked to, but I'll post back later if it prompts any further thoughts.

Best regards,
-- Al

Thanks, Kijanki. Agreed on all counts, although IMO the words "little bit" in your post should be particularly emphasized.

To quote an excerpt from page 4 of the article:

I performed the same tests using the low-jitter PS Audio Lambda transport as source. The results were very different. With a good source, cable direction didn't make a difference in the measurable jitter (fig.10). This suggests that the SV-3700—or any poor-quality transmitter—reacts with the cable's impedance to create jitter-inducing reflections in the interface. The directionality was probably caused by differences in the way the two RCA plugs were soldered to the cable; any bumps or discontinuities in the solder or RCA plug will cause a change in the characteristic impedance, which will cause higher-amplitude reflections in one direction than in the other. These reflections set up dynamically changing standing waves in the interface, introducing jitter in the embedded clock. These problems were reduced by the Lambda's higher-quality output circuit. In short, the worse the transport, the more cables—and their direction—affect sound quality.

Exactly what I speculated in my previous post, with some added elaboration based on the measurements that were performed.

Best regards,
-- Al

Mike, thanks for your comment.

Getting back to speaker cables, it occurs to me that what I said about connector-related impedance discontinuities in relation to digital cables may have some applicability to speaker cables as well. Speaker cables will to some degree act as antennas, picking up Radio Frequency Interference from various sources, such as nearby cables, power cords, digital components, switching power supplies, light dimmers, fluorescent lights, possibly wifi and even radio stations. That RFI will presumably be at frequencies that are too high, and at amplitudes that are too low, for the speakers to reproduce it and for our ears to hear it. However if the amplifier uses feedback, and if (as I would expect to often be the case) the amplifier's output impedance at RF frequencies is significant, some of that RF energy will be introduced into the feedback loop. Non-linearities and intermodulation effects within the amp may then result in that energy affecting sonics at audible frequencies.

And the magnitude and frequency characteristics of the RFI that is injected into the feedback loop can be expected to vary to some degree depending on the differing impedance discontinuities and mismatches at the two ends of the cable.

The magnitude and frequency characteristics of the RFI that is injected into the feedback loop might even differ significantly depending on the exact physical placement of the spade lug or other termination on the binding post, and/or its positioning relative to nearby metallic surfaces on the amp. As I said early in this thread, when hard to explain and/or seemingly implausible phenomena are being addressed, multiple back and forth comparisons are called for, to be sure that the observation is being attributed to the right variable, as well as to verify that perceived differences are perceived consistently.

Best regards,
-- Al

12-19-14: Geoffkait
Al, what difference does it make if the speed of the electromagnetic wave is variable? For the purpose of argument let's say the speed vary between half the speed of light (or about ninety thousand miles per second) and say 3/4 speed of light (or about 135,000 miles per second). Are you suggesting that a difference of a foot or two in cable lengths would be audible due to difference in time it takes the signal to travel the length of the cables? Now, the dielectric material could affect the sound, but that's a different issue.

Geoff, I'm suggesting no such thing. I was just correcting a misstatement of fact. I agree completely that differences in signal propagation times will be of no practical or sonic significance whatsoever, under any reasonable circumstances, even if the two cable lengths are significantly unequal. I say that despite the fact that some cable marketing literature would have us believe otherwise. And I say that despite the fact that deep bass frequencies propagate a good deal more slowly than higher frequencies, perhaps 50 times more slowly at 20 Hz, according to what I consider to be a highly credible paper I recall seeing.

As you alluded to, however, several other cable parameters and cable effects, which under some circumstances might be sonically significant, are proportional to length. As I indicated to you and others in the recent thread on unequal cable lengths.

Regards,
-- Al

P.S: Here is the paper I referred to above. See Figure 2, although it addresses a coaxial cable rather than speaker cables. At 20 Hz the propagation velocity, while much slower than at higher frequencies, is about 5,000,000 meters per second, easily fast enough to be utterly inconsequential in the context of a home audio system.

Regards,
-- Al

12-23-14: Scvan
I would really be interested in the study from hi-fi tuning. Can someone point me to a link?

Here it is. My comments on it can be found in the first of my posts dated 5-14-12 in this thread.

If I recall correctly, there was a revised version of this paper that was subsequently issued by HiFi Tuning, providing measurements of some additional fuses and incorporating some minor changes. I recall stating that my comments about the first paper remained applicable to the second one, but I can't find the link offhand.

Regards,
-- Al

Measurements, analysis, listening, and the instincts, experience, and intelligence of the designer are all key factors influencing the degree of success or failure that will be achieved in the design process. That's the bottom line, IMO.

Happy holidays!
-- Al