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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
geoffkait's avatar
geoffkait
23,365 posts
 
Atmasphere wrote,

"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."

i actually wouldn't be quite so hasty to dismiss fuse directionality out of hand. Let me give you exhibit A, interconnects. A certain kind of interconnect, one without a shield. The keen eared listener will discover that interconnects are directional, too. Just like fuses. Just like any metal wire conductor. This is precisely why many cable manufacturers mark their cables, the unshielded cables, with arrows, so that the cables are connected on the correct direction. Anti Cables marks their cables and they are just copper with lacquer covering. Audioquest and others mark their cables as well. Obviously some companies mark their cables with arrows only for the purposes of the shield.  If you have interconnects that don't have shields it's worth reversing them and seeing if that sounds better. I suspect this is true for both solid core and stranded. Speaking of which, the only way fuses or wire wouldn't be directional is if the conductor was some amorphous material like carbon or even lead, just for example, you know, non crystalline.

almarg's avatar
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almarg
9,670 posts
 
Gs5556, well said IMO.  I've had occasion to make similar comments about those measurements in a number of other fuse-related threads, such as in a post dated 4-8-2016 in this thread.  An excerpt:

Regarding the measurements described in the HFT paper ... which purport to support the notion of fuse directionality:

1)Resistance measurements related to directionality were provided for 16 different HFT fuses, having current ratings ranging from 1.6 amps to 20 amps, as well as for a few competitive fuses and standard glass and ceramic fuses (the specific make of the "standard" fuses being unspecified). The differences in resistance for the HFT fuses in the two directions ranged from 0.000002 ohms to 0.000120 ohms. The differences in resistance for the competitive fuses were a bit greater in some cases, with the worst cases generally being the standard fuses, for which there was one isolated case having a measured difference of 0.005200 ohms.

IMO those numbers are so miniscule as to be:

(a)Laughable.

(b)Very possibly attributable to changes in the voltage of the battery in the measurement meter, from measurement to measurement (each measurement imposing a slight drain on the battery), and from minute to minute. Or if the meter was AC powered, to the very slight differences in AC line voltage that may occur from minute to minute, as various loads are turned on and off at nearby locations.

(c)Very possibly attributable to differences in contact pressure and contact area between the meter’s probe tips and the contacts on the fuse. The paper presents separate measurements of fuse resistance as measured in a fuseholder (for just one direction), indicating that the direction-related measurements were performed by touching the meter leads directly to the contacts on the fuse.

(d)Perhaps even contributed to by differences in the resistance of the measurer’s body, that would have been paralleled with the resistance of the fuse if he or she had fingers on the probe tips and/or the fuse contacts while the measurements were being taken.

(e)If Geoff’s comments about all wires being significantly directional are to be believed, then these differences would be totally swamped by both the resistances and the alleged direction-related resistance differences of the vastly longer associated wiring. In the case of mains fuses, that would include the power transformer and the power wiring in the component, as well as the power cord and the AC wiring in and outside of the house.

Best regards,
-- Al
 
geoffkait's avatar
geoffkait
23,365 posts
 
Just to comment that the way I read the voltage drops is not at all like some other folks, I.e., the naysayers. Here’s how I read them. The differences in voltage drops are not responsible for the differences in sound, they are intended to be only a clue that something is going on. If a fuse was electrically symmetrical wouldn't it measure exactly the same one way as the other? The fact is even the independent tester commented that the voltage drop differences don't correlate with the sonic differences heard in fuse directionality listening tests. I suspect if someone, and I’m not mentioning any names, were to measure *distortion* in the fuse or say *noise* then we might see some more uh convincing differences between fuse directions, not to mention between cryo’d and uncryo’d fuses. Therefore, I wouldn’t get too hung up on the obviously slight differences in voltage drops.

cheerio
mapman's avatar
mapman
22,096 posts
 
Yawn. 
geoffkait's avatar
geoffkait
23,365 posts
 

mapman
13,349 posts
05-27-2016 4:36pm
Yawn.

No. 13,349. Thanks for your input.  Are we keeping you up past your bedtime?
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