PS Audio PWD MKII HiFi Tuning fuse direction

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

Al, I agree that the measured differences are relatively small compared to what one would expect (to explain the sonic differences heard by users). The manufacturer admits in the text of the data sheets regarding Noise that, "The measurements done so far showed some measurable differences between fuse(s), but didn’t explain completely the sonic differences between fuses." In other words, the manufacturer hears significant sonic differences between various types of fuses. As for fuse directionality, the manufacturer, HiFi Tuning, used to be adamant in his belief that fuses, in particular HIS fuses, were NOT directional - that no matter which direction the fuses were inserted they would eventually Break In to yield the same results. But at some point he changed his mind completely. One assumes he then had to learn how to keep careful track of the wire orientation as it travels through the fabrication process so that by the time the wire winds up inside the fuse the direction of the ARROW on the fuse body is correct.

Edorr wrote,

"Geoff, again, the difference are measured in a DC circuit."

I never suggested otherwise.

"AC current switches direction 60 times per second. Even if the fuse is directional, you would not hear it in an AC circuit."

I never said you would. But, really, what harm could there be in trying both directions, anyway, even in a DC circuit? Stranger things have happened.

"The paper does not even suggest you would."

I never suggested otherwise.

"So lots of reasons to be skeptikal about claims of hearing directionality differences in an AC circuit."

I guess the only way to be sure is try the fuse in both directions in an AC circuit. Better safe than sorry.

Geoff, the poster specifcally asked about application of a (directional??) fuse in an AC circuit.

If something can be categorically ruled out on undisputable theoretical basis, I personally would not advocating trying it anyway because "stranger things have happened" and it is better to be "safe than sorry".

If you take this philosophy to its logical consequences, all bets are off. For example, you could consider moving your DAC to other side off your audio rack and hear if it makes a difference. You should also try the black and silver version of any given component before deciding what to buy...

Edorr wrote,

"....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...."

I think the differences should be obvious to any Yutz with ears right away. But if the listener is hearing challenged or the system is not up to snuff, it won't matter how many A/B tests are performed.

"I personally would discount any reports that are not confirmed in double blind test, where the observer repeatedly picks the optimal orientation."

I did not see that coming. One wonders, have you ever actually had to sit through one of those double blind tests? Who can sit still and pay attention long enough to get through all the repeated tests? Unplug the power cord, take top off the component to access the fuse, reverse the fuse direction, screw the top back on, plug the power cord back in, listen. Repeat 10 times. LOL