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Direction of aftermarket fuses (only for believers!)

It is with reluctance that I start another thread on this topic with the ONLY GOAL for believers to share their experience about aftermarket fuses.
To others: you can call us snobs, emperors w/o clothes,... etc but I hope you refrain posting just your opinion here. If you did not hear any difference, great, maybe there isn’t.

The main driver for this new post is that I am starting a project to mod my NAD M25 7 ch amp for my home theater. It has 19 fuses (2 per channel, 4 on the power supply board, 1 main AC) and I will try a mix of AMR Gold, SR Black and Audio Magic Platinum (anyway that is the plan, I may try out some other brands/models). As it is reasonably difficult to change them, esp the ones on each channel module that requires complete disassembly, I would like to know what the direction is for these models mentioned and of course, others who HAVE HEARD there is a difference please share your experience on any fuse model you have tried.

Fuses are IME directional:
Isoclean is one of the first to indicate the direction (2008/2009) on their fuses. Users of HiFi Tuning (when the awareness rose quite a bit amongst audiophiles) have mostly heard the difference.

As an IEEE engineer, I was highly skeptical of cabling decades ago (I like the speaker design of John Dunlavy but he said on many occasions that cables nor footers matter at all, WRONG!). Luckily, my curiosity proved me wrong as well. I see the same skepticism that I and many others had about the need for aftermarket cables many, many years ago now on fuses and esp on the direction on fuses.

Another example is the direction of capacitors (I do not mean electrolytic types). Even some manufacturers now and certainly many in the past did not believe it can make a difference sonically. Maybe some do but it takes time in the assembly to sort and put them in the right direction/order (esp as some of the cap manufacturers still do not indicate "polarity") so that maybe is one argument why this is not universally implemented.








128x128jazzonthehudson
jea48
4,446 posts
 

atmasphere said:

 I joined this thread recently with some results on testing. Those results are that the directionality appears out of coincidence and that actually greater improvement can be had by rotating the fuse in the holder for best contact. The improvement is measurable and audible; descriptions others have made on this thread of what happens when you get the direction right accurately describe what happens when the contact area is maximized.

Occam’s Razor has something to say here! Given that a fuse has to be used in AC circuits and given that people report differences by reversing the fuse, and also understanding how fuses are inherently incapable of having directionality in any way whatsoever, the explanation that they somehow have an effect by reversing them in the holder is a fairly complex explanation: some sort of unknowable, unmeasurable quality of the fuse itself.

A simpler explanation is that the reversal is improving the contact area because fuse and holder are not dimensionally perfect and the fuse might sit better in the holder in one direction. By rotating the fuse in the holder without reversing it gets the same effect only more profoundly.


+ 1.

Great post!


jea48
4,446 posts
 

almarg posted:

Atmasphere 5-26-2016 12:31pm EDT
... I joined this thread recently with some results on testing. Those results are that the directionality appears out of coincidence and that actually greater improvement can be had by rotating the fuse in the holder for best contact. The improvement is measurable and audible; descriptions others have made on this thread of what happens when you get the direction right accurately describe what happens when the contact area is maximized.

Occam’s Razor has something to say here! Given that a fuse has to be used in AC circuits and given that people report differences by reversing the fuse, and also understanding how fuses are inherently incapable of having directionality in any way whatsoever, the explanation that they somehow have an effect by reversing them in the holder is a fairly complex explanation: some sort of unknowable, unmeasurable quality of the fuse itself.

A simpler explanation is that the reversal is improving the contact area because fuse and holder are not dimensionally perfect and the fuse might sit better in the holder in one direction. By rotating the fuse in the holder without reversing it gets the same effect only more profoundly.


almarg said:

Thank you, Ralph. I for one cannot envision a more persuasive case being provided on either side of the issue.

I couldn't agree more.








geoffkait's avatar
geoffkait
23,365 posts
 
Occam's razor (also written as Ockham's razor, and lex parsimoniae in Latin, which means law of parsimony) is a problem-solving principle attributed to William of Ockham (c. 1287–1347), who was an English Franciscan friar and scholastic philosopher and theologian. The principle can be interpreted as stating: Among competing hypotheses, the one with the fewest assumptions should be selected.

Therefore, going by Occum's razor as Atmasphere suggests, the hypothesis with the fewest assumptions would be that the fuse itself is directional, not the fuse holder. That would be like trying to solve two simultaneous equations in three unknowns. By testing the fuse in the fuse holder you cannot with certainty conclude which one is producing the directionality. Eliminate the fuse holder from the equation and all will be revealed. I strongly suspect that the outfit that performed the tests on fuse directionality for HiFi Tuning fuses, for Isoclean Fuses, for stock bog standard fuses, with and without cryogenic treatment, in DC and AC circuits would have observed that the fuse holder was producing directionality if that was the case. But they didn't. End of story's now if any of the naysayers wishes to get serious, and roll up his sleeves and test fuse holders for directionality and submit his results here I would be happy to comment.

jea48
4,446 posts
 

atmasphere,

Again, great post. The best explanation I have heard to date for fuse directionality. I would think it should satisfy those that have experimented with fuse directionality and say they can hear a difference. I would think it should also satisfy those that say they did not hear any difference, when they reversed the direction of the fuse.

Three important parts for a good electrical connection:

Cleanliness. (Free from contaminants and or corrosion)

Contact surface area. 

Contact pressure.



Your explanation makes more sense, at least to me, that the directionality of the fuse has to do with a VD, voltage drop, across the fuse element itself. That assumes the VD across the fuse would be measured in millivolts.

 Millivolts...... If that was the reason, wouldn't the same reasoning hold true for the AC mains line voltage feeding the fuse? In other words a small VD in millivolts on the mains feeding a piece of equipment could/would have an impact on the SQ of the piece of equipment.   Not hardly....

 


geoffkait's avatar
geoffkait
23,365 posts
 
As it turns out the resistance measurements of the various fuses tested that appear in the data sheets on the HiFi Tuning website were done on the fuses only in both directions. Separate resistance measurements for the fuses in the fuse holder are also provided. Refer to page 2 of the data sheets for the resistance measurements in both directions. The interpretation of measurements is presented on page 3.

http://www.hifi-tuning.com/pdf/wlfr.eng.pdf





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