PS Audio PWD MKII HiFi Tuning fuse direction


What is the correct / preferrable HiFi Tuning Supreme fuse direction in a PS Audio PWD MKII? I heard arrow pointing from back to front.

Fuse is not easily accessible to roll so just want to confirm.

Thanks!
knghifi
The fuse sits in the AC circuit .... I go along with the alleged efficacy of a lot of hard to rationalize tweaks, if someone says they hear a difference. But directionality of a fuse in an AC circuit goes too far even for me.
Well now, I suggest you try it both ways and get back to us.
Well, I can't say which way is correct on the PS Audio, but it's worth getting the direction correct. I heard a pretty clear improvement with HiFi Tuning fuses when I got the direction right. Worth the effort
i tried it both ways....noticed zero difference.
I use these fuses to excellent effect in my vintage Sansui tuners and directionality makes an obvious difference. Why would it make a difference on e.g., interconnects but not fuses?

Neal
It doesn't make a difference in cables or fuses. Electrons do not care what arrow direction a manufacturer may put on a label.
Because 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. How can directionality of a fuse make a difference when the direction of the current flowing through that fuse changes direction 60x per second?
I have hard time rationalizing directionality of cables and fuses, but in a DC circuit we can at least entertain the idea it makes a difference. In an AC circuit in my view it is categorically impossible there is a difference.
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
Hk_fan wrote,

"It doesn't make a difference in cables or fuses. Electrons do not care what arrow direction a manufacturer may put on a label."

Electrons don't carry the signal so I suspect we can probably rule that particular theory out. In fact, electrons in the conductor are kind of just sitting there, drifting along at a couple centimeters a minute.

GK
MD
Almarg wrote,

"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."

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.

http://www.kempelektroniks.com/Site_files/43/4300d6c0-5d8a-4774-bfde-f8b0088606b8.pdf

GK
MD
....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 personally would discount any reports that are not confirmed in double blind test, where the observer repeatedly picks the optimal orientation.
I totally agree with Al and Edorr, but for the sake of your peace of mind, Knghifi, install back to front as you noted in your op. This was discussed on the PS Audio forum.

Cheers!

_Ben
The differences in directionality are only reported in a DC circuit. The AC measurement do not have a direction 1 and direction 2 measurement, because in an AC circuit there is no directionality. The flow of current changes direction 60 times per second.

Even the difference in directionality in the DC circuit are methodologically suspect.

First, the report does not say if the best measurement for the allegedly directional fuses correspond with the recommended direction. If you do two measurements there will always be a random difference between two measurements. To proof directionality, you need a batch of allgedly directional fuses, measure each one multiple time and show that the recommended direction measures better within statistical margins of error. There is no indication at all this is what they did. The report does not even say what the standard diviation is for the measurements, and therefore you cannot tell whether or not the differences are statisically significant or random.

Second, the difference between direction 1 and direction 2 measurement is higher in the non directional cheap fuses, than in the allegedly directional high end fuses. If the expensive fuses were explicitly designed to be directional, you would expect the exact opposite.

In conclusion, directionality of fuses in AC circuit is bogus, and in DC circuit highly suspect.
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
"Electrons don't carry the signal so I suspect we can probably rule that particular theory out. In fact, electrons in the conductor are kind of just sitting there, drifting along at a couple centimeters a minute. "

With all due respect, you don't know what you're talking about.
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. Of course, measured differences might not be audible but if someone is looking for a smoking gun, this new data is just that! I don't get it, if you can measure it and you can hear it, what else is left to be so skeptical about? Seems silly.

GK
MD
Geoff, again, the difference are measured in a DC circuit. AC current switches direction 60 times per second. Even if the fuse is directional, you would not hear it in an AC circuit. The paper does not even suggest you would. So lots of reasons to be skeptikal about claims of hearing directionality differences in an AC circuit.
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.
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,

"....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
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,

"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..."

Of course you can come up with all sorts of absurd examples. How difficult is it to try the fuse both ways? What are you afraid of?
I'm afraid of wasting my time. To me the notion of sound quality difference through directionality of fuses in an AC circuit is as absurd as the notion as the black chassis sounding different than the silver.
now that was funny Ed!

wondering if i made a mistake getting the silver pwd2 =)
Obviously you have not heard the PWD mkii black version yet. It sounds best on the top shelf on the left. I had it on the right for a while. Big mistake.
10-24-12: Edorr
I'm afraid of wasting my time. To me the notion of sound quality difference through directionality of fuses in an AC circuit is as absurd as the notion as the black chassis sounding different than the silver.
Edorr (System | Threads | Answers | This Thread)
The reason I started this thread is I hear differences in directionality of fuses with components in MY system plus not easy to roll them in PWD. It's very possible you don't hear a difference /and in YOUR system. So you are wasting your time trying to convince others that do hear a difference but thanks for sharing your experiences with the group.
I love these recurring arguments without the presence of the op. Is he learning anything? Has he tried the fuses and made a determination? Does anyone really give a $h!!?
I am not disputing you may hear a difference in a DC circuit.

In response to your question, I am just poining out that based on the laws of physics it is categorically impossible that in an AC circuit there is a difference depending on what you direction you put in your fuse, because the direction of the current itself changes direction 60 times per second.

This is true even it the fuse itself is "directional". Paul McGowan of PS audio has made the exact same argument on the PS audio forum. So far, no one has disputed this, but the argument is made "why not try anyway". To me this defies all logic, but that's just me.
I'm a simple person, I use my ears as the ultimate purchasing decision for audio, eyes for video, taste for food, how I play for golf clubs and tennis rackets ... I have a technical background but frankly most of the time it's not important for me to get stuck in the weeds trying to understand why something works. Life is too short and there are bigger fish to catch.

Fuses are REASONABLE ROI so a no brainer for me. I pick my spots ...

There are so many variables with one's hearing, quality of components ... so not trying to convince anyone and not interested in a debate. It's your $$ and time so use whatever is best to YOU.

I know there are many that likes to play Einstein on Agon so go measure away.
Hearing differences in the directionality of fuses is a feat that deserves great attention because it is likely a rare phenomenon. The world has seen many exceptional human feats and this is certainly one of them. I'm thrilled to be in the presence of someone so unique. It's my true pleasure.

Don't waste that god-given talent...

Cheers!

_Ben