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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
mapman's avatar
mapman
21,952 posts
 
You'd think but no.  🏄
jazzonthehudson's avatar
jazzonthehudson OP
277 posts
 
Jim, thanks for the extract from John Curl! From the electrical point of view, a VD should not matter much. Your comments was also incorrectly interpreted by me ( Al, thanks for the small but important addition of "THAN" ), hence my thought of possibly testing same brand fuses with different breaking points/capacities.

My best guess is that the vibration control/dampening (e.g. use of special liquids, beeswax, dampening material in Bussman) is a very important determinant, as well as the metallurgical composition and treatment (cryo) of fuse / fuse filaments. 


thaybran's avatar
thaybran
6 posts
 

Hifi Tuning Supreme silver work well in both directions depending on taste on some music I tend to switch it round in the pre amp.

1 way sounds fuller with a large stage when direction switched things become tightly focused with a more direct presentation

I am using a 13amp syn research red fuse on my argentum powercord and switching round makes no difference to sound whatsoever

Post removed 
atmasphere's avatar
atmasphere
11,667 posts
 
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....
You are correct in your first statement of this paragraph. An important question might be 'what is meant by 'small'?' In one of our preamps I measured a 158mV (0.158V) drop; in one of our amps I've seen a 2 volt drop cause a loss of 40 watts at the output of the amp. In the case of the preamp the power supplies are heavily regulated so I do not expect to hear anything from a voltage drop on the line nor do we in practice. So we can assume that some types of equipment are far more sensitive to this issue than others!

The line voltage determinately effects the sound of a lot of equipment. This should come as no surprise to many of us here who have experienced the system sounding like Nirvana on one evening and the next day falling well short. So much has to do with line voltage which fluctuates, but also with how easily the line voltage can sag as the equipment is running (a further issue is distortion of the AC sine wave which is not part of this discussion).

A fuse is one of those spots in that set of connections from the wall (AC power connectors, power cord and the fuse and holder) that is likely the 'softest' which is to say that the sag occurs easier at that point, due to contact area and conductor size (the effects being limited by the fuse being so small). Part of this is due to the nature of the fuse itself, the other part due to its connection into the system.

This ties directly into the power cord conversation (a very real and measurable phenomena) and its effect on the system sound.

On a different website I encountered an individual who was of the objectivity camp (measurements) who was adamant that power cords could not make a difference in system performance. When challenged on the subject, I discovered he had never even tried to measure the performance of a power cord and thus had no measurements! To individuals who live and die by measurement, I appear to be a subjectivist; I found it quite ironic that he lacked the measurements while I did not.

I'm not sure how I come off on this site but to be clear I like to know why I hear certain phenomena and so try to see if its measurable. Quite often it is.

In this case, its a simple fact that you can measure the voltage drop across the fuse. Depending on the equipment in use and your measurement technique, you can see that voltage drop vary somewhat with the audio signal. It could be construed that this could introduce IM distortion.  IM happens to be audible to the human ear so it should come as no surprise that the effects of the fuse can be heard.

Our customers have been saying this all along as I have maintained elsewhere on this site. It took the obviously specious argument that the fuses were somehow directional to cause me to take a look at why people might think that. A simple DVM showed why and anyone who puts the DVM in AC voltage mode and simply measures across the fuse connections will see a number appear on the meter readout. This is not hard to do! Further measurement might show that by rotating the fuse in the holder the voltage drop can be altered. Sometimes you might have to reverse the fuse to optimize the contacts because the fuses we are dealing with are not always perfectly dimensioned so it might get better contact area in one direction as opposed to another. This does not mean that they are directional- it simply means they are not built precisely.
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