2. cables
  3. 124345-1776

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
 
"With 19 fuses and either direction the choice, if my math still works correctly, I think that would be 2e19 combinations, which would be fun to perform and see what the optimal combination was by listening. Could be a hobby for lifetime and then some."

The correct way to look at the situation mathematically is that if you replace all existing stock fuses with aftermarket fuses at the same time - without any thought as to each fuse’s orientation - simply by chance approximately 50% of the new fuses will be inserted correctly, let’s say 10 fuses, more or less. So you're already halfway there without doing anything yet. Allow fuses to burn in for say 100 hours to give yourself a better chance of hearing differences in directionality. Then, reverse fuses one at a time and audition the sound after each fuse reversal. You should be able to tell whether the sound improves or degrades each time. If the sound degrades put the fuse back the way it was. It should get easier to decide the correct direction of each subsequent fuse since the sound quality will improve as more and more fuses become correctly inserted. If you're unsure about a particular fuse leave it as it is. You will come back to it later.

After you have completed auditioning all 19 fuses the probability will be much higher that all fuses are now in the correct orientation. It would not be unusual that during the whole auditioning process there was some uncertainty about one or more fuses’ orientation. For that reason the entire auditioning process should be performed again. The second time around, with most fuses inserted correctly already, thus with higher system resolution and sound quality, it should be much easier to ascertain which direction is correct for each fuse.

Geoff Kait
Machina Dynamica
no goats, no glory


charles1dad's avatar
charles1dad
10,250 posts
 
Hello Mapman,
The lettering on the Synergistic Research fuse reads the standard left to right direction. In my DAC the fuse holder is orientated L to R.  In my Coincident components the  fuse is inserted into the rear fuse holder in a back to front orientation.  So the lettering is read as first letter begins at the component rear and last letter towards the front of the component.
Charles, 
geoffkait's avatar
geoffkait
23,365 posts
 
This popped up during an Internet search. It’s written by Ted at Synergistic Research. What he’s saying here is that the lettering on the fuse is only a tool to show the direction of the fuse before you reverse it, so you won’t lose track and accidentally insert it the same way as before. I.e., The fuse lettering doesn’t really go in the direction of current. You have to try the fuse both ways. Hel-loo!

"In my experience nearly all fuses are directional including SR Quantum Fuses. I recommend you try them in one component at at time and experiment with directionality. You should immediately notice a preference for one direction or the other. If a component has more than one fuse use a DVM (Digital Volt Meter) to determine direction of current in the circuit. Once you know the direction of current in each fuse holder place all fuses in like direction paying attention to have the letters on the SR Quantum Fuses all in the same direction either reading in the direction of signal flow, or against. Next switch direction and the correct match to your component should be readily apparent. There are just too many variables for me to make a blanket recommendation for all components when such a simple and definitive test is available."
mapman's avatar
mapman
22,300 posts
 
" If a component has more than one fuse use a DVM (Digital Volt Meter) to determine direction of current in the circuit. "

The problem with this of course as many have pointed out repeatedly in various threads is with alternating current direction switches many times per minute.

As I understand it it is possible to determine power flow direction in an AC line, for example with an overhead transmission line which way is the source (the power plant). With a circuit schematic perhaps it is possible to determine which way to the components power supply from any particular fuse location? That would be a question for Almarg or other EEs perhaps to answer.

The thing is assuming fuses are directional and that orientation is a significant factor for best sound, you would look for devices that have the directions clearly indicated somehow plus a fuse with the same so things can be done easily without an electronics background. If all that is true but no indicators, someone in design was asleep at the wheel and the customers are paying the price to have to figure it all out.

Could you imagine buying an expensive portable device using 19 batteries in 19 different locations and no indicators which way to place each? That is essentially the worst case scenario for teh NAD assuming fuse direction always matters.
geoffkait's avatar
geoffkait
23,365 posts
 
Mapman, you probably didn’t get the memo. Fuses are not only directional in DC circuits, they’re directional in AC circuits, too. You know, when the alternating current is moving in the correct direction the voltage drop is measured as lower across the fuse than when the current is moving in the other direction. Capish? Yes, I know you wish only to learn, Grasshopper.  But first you have to put on your thinking cap.
More to discover