PS Audio PWD MKII HiFi Tuning fuse direction

Why would it make a difference on e.g., interconnects but not fuses?

There are at least two relevant differences between the two situations:

1)Many interconnects are asymmetrical by design, having a shield that is grounded at only one end. The intent being that noise which may couple into the cable will be conducted to the output of the component that is driving the cable, and not to the destination component.

2)Most and perhaps all cable effects, at least those that are technically explainable, are proportional to length. Obviously the length of the conductor in a fuse is miniscule compared to the length of an interconnect.

Interconnects sit in a DC circuit, where current flows in one direction. The fuse on the PWD sits in an AC circuit meaning the polarity switches 60x per second.

Actually, the first sentence is not true. DC is a frequency of zero Hertz. While the circuit stages that generate and process analog audio signals are powered by DC, the analog signals themselves are a mix of AC components that are at many different frequencies, mainly between 20 and 20,000 Hz. There may be trace amounts of DC that are present for various reasons, but the speakers can't reproduce it and we can't hear it.

Some will say that fuses are directional because energy is being transferred through them in just one direction, or because during manufacture the conductive material they contain was "drawn" in a certain direction. Whether or not fuses in fact have any directional characteristics, the relevance of those facts is IMO speculative at best, and most likely unprovable.

Count me as being in the skeptic part of the spectrum, but with a mind that is not totally closed on this issue. I would, however, discount any reports of perceived differences in which the person did not go back and forth between the two orientations at least several times. Not only to assure that perceptions were accurate, but to rule out the possibility that extraneous variables were responsible, such as contact integrity, warmup status of the equipment, changes in line voltage or noise conditions, etc.

Regards,
-- Al

10-22-12: Geoffkait
I suspect one need look no further than the measured data for fuses of various types, including standard and HiFi Tuning, to see that fuses not only measure differently but are directional electrically.

Geoff, I had provided detailed comments on a similar set of measurements from the same folks in the recent "Fuses That Matter" thread, in my post dated 5-14-12. The bottom line:

IMO they provide the basis for a good case as to why fuse upgrades shouldn't make a difference, or at least a difference that is necessarily for the better.... I don't exclude the possibility that a fuse change can make a difference, but once again the explanations that are offered in support of the existence of those differences do not withstand quantitative scrutiny.

I would add to my comments in the other thread that one could take two identical examples of a specific model of any given electronic component, such as a preamplifier, amplifier, digital source, etc., and find within it countless examples of parts such as resistors, capacitors, transistors or tubes, integrated circuits, etc., having greater and arguably more significant measurable differences between the characteristics and parameters of corresponding parts in the two supposedly identical components.

The existence of a measurable difference does not by any means necessarily imply the existence of an audibly significant difference. And if there is an audibly significant difference, it does not by any means necessarily imply that the measured difference is the reason.

Regards,
-- Al

10-23-12: Geoffkait
Al, I believe the fuse data to which I provided a link above is new and different from the previous data under discussion a while back inasmuch as the new measured differences are much more pronounced.

A lot of it is new, presenting data on different fuse types in many cases. But I don't see any major differences between the two sets of data, or anything that would change the comments I provided either above or in the other thread (aside from the fact that the vector impedance data that I had indicated was missing from the other paper has now been added).

All of the text in the new paper that provides interpretations of the data is identical to text that appeared in the other paper. Including, btw, the remarkable admission that the worst case power loss due to voltage drop across any of the fuses is “very small in comparison to typical variations in line voltage of average 3%.” A point I had made early on in the other thread. In regard to which I also pointed out that if the line voltage at the user’s location happens to be higher than the line voltage at which the component was developed and voiced, the larger voltage drops of the standard fuses will be in the direction of helping, not hurting, if in fact they have any audible consequences at all.

Concerning the directionality-related measurements specifically, in addition to the good comments Edorr has provided in his last couple of posts I will repeat a basic point I made in the other thread:

If per my comment and Roger [Modjeski's] comments the OVERALL resistance for both directions is insignificant, the DIFFERENCE in resistance between the two orientations will certainly be insignificant.

In any event, my comment in this thread that you originally were responding to was:

Some will say that fuses are directional because energy is being transferred through them in just one direction, or because during manufacture the conductive material they contain was "drawn" in a certain direction. WHETHER OR NOT [emphasis added] fuses in fact have any directional characteristics, the relevance of those facts is IMO speculative at best, and most likely unprovable.

I don't see anything in either set of data which calls that statement into question.

Regards,
-- Al