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.

So, what’s the question or point here? I mean, you have a position on this issue and are convinced that it holds scientific or quantitative value. Therefore, the combination of correct fuse orientations across all 19 fuses in your NAD must have some predictive outcome. Put them in their correct orientation, and enjoy.  Emotional states, i.e., belief systems, can bear greatly on the listening/hearing experience.
Stevecham, that’s an excellent question.

After al this discussion, you’d think the OPs question would be answered at this point and guidelines for getting all his stuff oriented correctly clear and doable.

Has any of that happened? Assuming fuses are directional in the sense that the direction actually matters to a significant degree for the resulting sound (listener biases and expectations aside) is op or anyone else any closer now to doing things right than when they started?

All this talk and analysis from all these smart people and is anyone any closer to the answer now than when the thread first started?

That’s my question. Each can have their own answer and take that for what its worth to them.

Assuming a better outcome is posible (not a safe assumption) its still a blind mans task.

Good luck! This would be funny at this point if not so sad that people might be misguided to spend their valuable time on such a blind man’s task at best IMHO. Only hard core audiophiles that have to get that last good fix of better sound they might be missing no matter what thanks to those who help feed people’s insecurities about what good sound they might be missing from their already excellent gear.

Not that there is anything wrong with that. People can choose to do much worse things in their spare time. Nobody is harmed as long as one is happy with what one is doing. People waste money on things all the time. It help keep the economy going.

Count me out. To those up to the task, good luck! You will need it! Unless its all in your head to start with perhaps. That makes things a lot easier.

Oh wait! I forgot. Geoff mostly just talks but Bo claims to have this all figured out and doable for his customers. Quantum chips too! Just go to him. Easy answer! That’s what experts are for!
Great start here. Isn’t here another thread that’s circling the drain which would be more appropriate for the 1st three posts?

Oh sorry. This is a new fuse direction thread.


Determining current flow to install "audiophile" fuses.

My mistake. Only for believers this time.

Well hopefully I helped get things off to a good start, but I will butt out then I suppose.

I am interested in any practical answers that might come up to guide the OP other than try things both ways and see, but have my doubts, so will stay tuned given that. Beliefs can change over time, right? All it takes is the right facts.

For example, for the fuses that have an arrow on them indicating direction,  how to know which way to point the arrow correctly?
Mopman wrote,

"Oh wait! I forgot. Geoff mostly just talks but Bo claims to have this all figured out and doable for his customers. Quantum chips too! Just go to him. Easy answer! That’s what experts are for!"

I'll talk to anyone who will listen.  Heck, I'll even talk to someone who won't listen. Think of it as Tibet Book of the Dead for Audiophiles.

Geoff, there are very specific questions being asked by the OP looking for very specific answers to apply for his NAD.

I’m waiting for your expert advice to help him.

I’m not biting on any baiting here . Let’s stay on topic.
Again, so much internet space wasted ... the reason for starting a new thread is exactly what I try to avoid:
on the previous one onlookers and know-it-alls filled up 90% of the thread with their assumptions.
Reading through close to 300 posts yielded little valuable, practical info.

On most threads we get comments "sure, go ahead and try this and that, as long as your wallet is comfortable with it", YMMV, etc but no, on the previous thread too many needed to voice their doubts about the direction of a fuse. Ever tried to ask some of the questions here on a forums at, say, Best Buy, like "does cable matter?"
You promptly will feel exactly the way how I feel here, thanks "audiophiles"! Great help! 

For clarification, I solicit comments like"
"..with the Audio Magic BeeWax, the direction goes like the lettering on the fuse (like HiFi Tuning)..."

Post removed 
In the case of the Audio Magic Beeswax fuse (assuming he’s using the same stock fuse as he did for the Super Fuse (which I had) to drill out and squirt in the beeswax) the stock fuse manufacturer is either unaware of fuse directionality or chooses to ignore it. Don’t they all? Lol Audio Magic itself most likely doesn't have the time and inclination to test each fuse. Thus, no arrows on the Beeswax. Now if Audio Magic made his own fuses, things could be different since he would have control over the wire, and it's correct direction coming off spool.

Ergo, unless I miss my guess, you won’t be able to go by the writing on the fuse for clues on directionality. Even if someone reported his Audio Magic Beeswax fuse sounded best with number and letters written in the direction of the current flow I would be a little suspicious that that is always the case or just random. I hate to judge prematurely or be overly skeptical in this matter, especially considering the rather large number of fuses involved in your case (OMG) but it appears you will have to follow the sage advice which has been given on these fuse threads many times: try the fuse both ways and see which is better. Looks like you will have to determine directionality the old fashioned way.


Geoff Kait
Machina Dynamica

Although like several of the others I have nothing constructive to say in response to the specific question that was asked, I can't help but question the wisdom of spending what figures to be $1000 to $2000, or possibly even more, on fuse upgrades for a 7-channel amplifier that sold for $2500 to $3000 ten years ago.

Many of those who have extolled the virtues of the fuse upgrades that have been discussed in the other recent threads have expressed the opinion that the higher the resolution and the quality of the components that are involved, the greater the benefits fuse upgrades are likely to provide.

My suggestion is that you initially just replace the mains fuse, which of course you can easily try in both directions, and assess that result before embarking on anything more ambitious (and expensive) internal to the unit.

-- Al

Great post almarg.
Though I did not think it would do much, changing the amps mains fuse to a HifiTuning fuse did result in a change in the sound of my stereo. (note: I bought the last of the previous version HifiTuning fuses at a discount-$80 bucks for a fuse is kinda silly, to me).
As far as directionality, I thought I noticed a difference, but I haven't had time to do a more 'controlled' test to confirm my suspicions. Contact me directly if you want more details.
Since I am always looking for the best bang for the buck (My system is Vandersteen/Zu, McCormack and Schiit), I would suggest looking at Acme Fuses. SMc thinks highly of this brand and they are more reasonably priced.
Hey, whaddya know? Al and I finally agreed on something. Try the fuse both ways. Halleluja! I have a feeling Mapman is probably biting his lip about now.

Geoff Kait
machina dynamica
we do artificial atoms rite
Almarg, as always, I very much appreciate your comments and knowledge. FYI I have been using aftermarket fuses since 2009, thank god I haven’t come out with it then as some on this and certainly on the other thread would have mentally burnt me on a stick.

My answer is less geared to you but more for those who landed here: first of all, the $ ratio between devices and "infrastructure" (*) is a function of the eye (ear) of the beholder. As an owner of HFC cables, I know that many have "overinvested" in magnetic cables, following their addiction. The question begs: if a $1k device, be it in the form of magnets with cables or "just fuses", can elevate the sound into a system that is $10k more (I know it gets fuzzy here), it may constitute a good ROI. In my case, I buy AMR fuses under $3 (no trailing zeros!) each. Rest assured, the main fuse is and will/should remain the most expensive one, then comes the four fuses for both channels. My total investment is est. around $400, a price of a power cord upgrade. Now if I would post a new thread asking advice for a power cord upgrade, I wouldn’t be chastized as much as here on this very thread.
Lastly, if one followed my threads, I have asked for a worthy successor of my NAD M25 months ago, no replies (maybe my thread on the NAD M25 wasn’t controversial enough) so either no interest or no valid alternative.

As mentioned on my systems page, regular visits to music events and sanity checks in the mirror (aka wallet) helps to mitigate straying too much from the path.

Now, again, besides the regulars here, would anyone share his/her experience on the direction of fuses?

(*) I have denominated infrastructure devices like isolation tweaks, cables, power conditioning, etc that enables/empowers the system. Some here on the Gon go as far (read crazy for the non-believers) as 70% invested in infrastructure.

How does one know if the markings are placed in the proper orientation by the seller? If the seller manufactures the fuses and determines the correct orientation or if he buys them OEM and places them a certain way during the treatment process, then all you have to do is ask him. Otherwise, whatever comments are offered are meaningless since the fuses are randomly oriented when marked.
I'm can appreciate your efforts for specific information about fuse direction. My experience with the SR Red  and Black fuses is they generally go in the direction of the writing. I would still suggest reversing direction as there always seems to be individual component exceptions. Without exception so far I hear noticeable differences in sound based on direction. I trust what I hear and leave the bickering for those so inclined. 
Jazz I'm glad you recognize that Al isn't an agitator who just wants to stir things up. 
Many have mentioned that the manufacturer may put on markings on a whim or can change the process so that the markings are done on the other end. Sure, it can and probably has happened for smaller batches. I am just trying to get a consensus so that I am best prepared for the starting position, which may be the best guess.

thanks for your feedback on SR fuses and happy to learn that SR has the same process for both red and black.
You’re absolutely right and, as mentioned before, I really appreciate the vast knowledge and the logical approach Al adopts in his comments. I quoted him exactly because he is an authority in his field and wanted to counter others who may use his words to put more fire on the wood. Also because I know he won’t be easily offended/stirred and am sure before he posts, he will read mine so he knows I have no intention to undermine his authority.
Now if I had quoted mapman or GK,...

Any best experience from NAD M25/M27 owners (which fuse worked best)?

I have no authority really to undermine.   Just another Shlub trying to figure things out. 🤔

Charles when you say they go in the direction of the writing. Which way is that?  

For or example batteries are marked positive and negative ends making them directional. With out doubt.    But if the battery compartment does not have similar indicators. You don't know which way to oeient them properly.  

Donthe he devices the directional fuses go into have some similar indicator or other way of telling?
Post removed 
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.
Somewhere else on another thread about fuses someone asked the manufacturer as to the direction of the signal as it goes its way and he was told "from the inside out". I'm assuming it's from the center (somewhat) to an outer edge.

Good luck and all the best,

"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

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.
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."
" 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.
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.
IMHO Ted at SR puts out a disclaimer and I think it is more likely that a manufacturer keeps the same process (why change?). AMR produced fuses en masse as did Isoclean and for the aforementioned brand, they are, so far, consistent IME (same as HiFi). Another indicator is that HiFiTuning users have consistently reported the direction in the same way as some SR users. Thanks Charles1dad and others for sharing this. It is people like you that has made this hobby more fun and trustworthy for me as I have made most of my purchases based on comments on the Gon. People like GK, though a bit overzealous in postings for my liking, seems to be genuinely interested to find out/help out. He may know that nerdy people can at times put off people (polarizing is only good for electric components) and sympathy counts when buying gear, hel-loo :-). May I also suggest using PMs (e.g. to mapman) instead of a public shout out? Thank you!

As for the circuitry, I know what upstream is as I have the schematics of the amp. Before submitting this dreaded thread, I have the following strategy: try first the fuses on L+R channels with open cover, assuming the fuses are labeled in the same way and proceed from there. Now I will resort to making sure that the 3 main channels (L, R, C) sound coherent. I simply don’t have time for the other channels and will assume that the labeling process is less random that I hoped for. This should be a 1-month project, included bypassing some caps, not a lifetime trial and error. I dread of the amp surviving me.

Again I would like to stump on the example of coupling caps (in tube amps, etc) where most manufacturers don’t care to implement it the correct way (aka polarity/direction), leaving improvements to modding shops and aware DIYphiles (wait, do I smell a conspiracy?).

Lesson learned, early adopters (we should have been over that for fuses but obviously we’re not) pay the price/scrutiny.

I sensed that the fire on my stake seems to fizzle out, you all have my gratitude for that!

Jazz, sorry for intruding on your soapbox.   Good luck with your endeavors.
I didn't intend to imply that the SR fuse lettering suggested current flow,  rather that this is the orientation providing the best sound quality consistently in my components. 
Charlesdad wrote,

I didn’t intend to imply that the SR fuse lettering suggested current flow, rather that this is the orientation providing the best sound quality consistently in my components.

Hi, Charles, can I respectfully suggest you re-read what I wrote? Also re-read what Ted from SR wrote. There appears to be no consistency from fuse to fuse regarding lettering or indication of direction. So you can't go by the lettering without trying both ways.

geoff at MD

JazzontheHudson, while you're probably already aware of this you can download a pdf of the service manual for the M25 via the following link, if you first complete a simple registration process at

In addition to the schematic you mentioned having, the manual includes printed circuit board layout diagrams and other information that might be helpful.

Thanks very much, btw, to you and Charles for the nice words.

Good luck as you proceed.  Best regards,
-- Al
Geoff, as I read it the Op would appreciate your help if not mine which is fine. Don’t just check out because of me. :^)
Thanks mapman and GK!

Al, thanks for the info, I got most of the manuals there at hifiengine and in this case, got the service manual directly from a good source at NAD. I try to have service manuals / schematics of most of my gear, primarily to understand where they come from design wise. Most tech departments understand why I wanted it and provide the info easily. If the manufacturer remains stubborn, sites like DIYaudio and others may shed a light. 

A side question: I enjoy the zapped products from SR: fuses, wall sockets (though Furutech GTX- D(r) remain my reference, havent tried the new NCF version) , etc. Have you experimented with superhigh voltage to create that tunneling effect in cables?

For others that feel "attracted": I have been using HFC cables for many years with pretty good results. I have stalled in my quest to create my own magnet cable (just for fun) as I can't find a suitable ready-made conductor cable, would be helpful for any practical hints.

*also a* Charles

You are welcome. Good luck.

" Lesson learned, early adopters (we should have been over that for fuses but obviously we’re not) pay the price/scrutiny. "

That is very true. They don’t call it the "bleeding edge" for nothing. :^)  Not for the faint of heart.....
As an IEEE engineer
Google failed to answer me on this- what's an IEEE engineer?
Post removed 
This was the first thing that came up when I googled it:
I saw that too. That's an organization, not a field of endeavor like mechanical or electrical engineering
I'm also an AIAA engineer.
Given your posts here, highly unlikely.  

Atmasphere wrote,

"This was the first thing that came up when I googled it:
I saw that too. That's an organization, not a field of endeavor like mechanical or electrical engineering"

Gosh, really?

Geoffkait: "I'm also an AIAA engineer."

to which Atmasphere retorted,

"Given your posts here, highly unlikely."

Good one!  I also know how to use Google.  


Jazzonthehudson 4-29-2016
Have you experimented with superhigh voltage to create that tunneling effect in cables?
No, I haven't.  My background is in analog and digital circuit design involving conventional voltages.

BTW, as I mentioned a while back in one of the other fuse threads, Wikipedia writeups dealing with quantum tunnelling make no mention of ultra-high voltages:

Best regards,
-- Al
(IEEE Life Member)

Al, have I fallen for a SR marketing trick? Their website states repetitively "... By applying a two million volt signal to a cable at a specific pulse modulation, and ultra high frequency for an exact duration of time, we transform the entire cable at a molecular level through a process we call Quantum Tunneling...."

FYI I was part of the AP/MTT chapter and worked for a large telecom equipment manufacturer so no high voltage experience. I did had fun with Microwave oven trafo powered arcing in labs though...

Ok, I've had a lot of experience with different fuses here.  I will agree that the direction of the print on Synergistic fuses does indicate the direction (at least it sounds better to me).  The same goes for Furutech fuses.  Of course, Hi-Fi Tuning and Isoclean already have a directional arrow printed on the fuse.  I have found that when the fuse is placed in the opposite of the preferred direction, the midrange has a weak / hollow sound to it and the overall sound does not have as much impact.

The Audio Magic fuses are just the stock "Little Fuse" brand.  They are decent industry stock fuses, but nothing special (like $4 a fuse).  Audio Magic drills and fills the fuse with an anti-vibration solution, which acts to reduce electrical resonances.  Resonance definitely plays a part in sound quality, but I have never tried an Audio Magic.  Also the Little Fuse wire element is nothing special (just tinned copper at best).  These were just too expensive for me to audition.

In my opinion, the choice of fuse really has to do with what direction you want to take your NAD.  From what I have read, NAD equipment can be very warm sounding.  This can come across as somewhat muddy or slow (similar to tube).  If you want to make the NAD more clear sounding and quicker/tighter, then I would look at the Synergistic SR20 or the Furutech.  The Furutech is the "fastest" sounding fuse I have tried.  It will really increase the punch, authority, clarity, and cleanliness of the sound.  The SR20 is the second most fastest fuse.

SR RED is probably the most non-intrusive fuse I have found.  It will make every piece of equipment sound "ok", but it doesn't make it "sing" (I think you actually lose some resolution with SR RED).  My experience with Hi-Fi Tuning Gold put a metallic etch on the sound.  I have not tried other Hi-Fi Tuning fuses or SR BLACK.

My favorite fuse is the Isoclean, which is also the cheapest.  It is great for solving problems with very bright "solid state" type equipment.  It adds a fullness and level of warmth to the sound and takes away a lot of the brightness problems.  The Isoclean works wonders in my equipment, but I use very strong and bright "solid state" style equipment (such as Krell, Bryston, Emotiva).  I have found the Furutech and SR20 fuses do not actually work out as well in this type of equipment because they make the equipment too "solid state".

Depends on where you want to go.  You can get Isoclean on ebay for $30 direct from China, and I'm sure it will improve things, but the Isoclean may not be fast enough for your tastes and equipment.

"The Audio Magic fuses are just the stock "Little Fuse" brand. They are decent industry stock fuses, but nothing special (like $4 a fuse). Audio Magic drills and fills the fuse with an anti-vibration solution, which acts to reduce electrical resonances. Resonance definitely plays a part in sound quality, but I have never tried an Audio Magic. Also the Little Fuse wire element is nothing special (just tinned copper at best). These were just too expensive for me to audition."

I had both the Isoclean and the Audio Magic Super Fuse (the model just prior to the Beeswax Fuse) and the Audio Magic Super Fuse was better. I used them both in a Woo Audio all tube Headphone amp with super modded Oppo 103 and naked Sennheisers 600s. The Woo Audio amp used 1942 Tung Sol rectifier and ’52 Sylvania Badboy output tubes. With the high cost of fuses these days, e.g., Audio Horizon, HiFi Tuning, SR Black Fuse, nothing should be off the table especially if you only have one fuse; the fuse on my Oppo was bypassed. ;-)

Here's the blurb for the new Beeswax Premier Super Fuse. Note the anti RFI/EMI blackout powder in the Premier Super and it's probably in the Beeswax too.

Audio Magic latest fuse in the Premiere line - The "Beeswax" Premiere Super Fuse. The Beeswax version is identical to the Premiere version the only difference is Audio Magic uses Beeswax instead of the normal anti vibration fluid, this gives the fuse a very organic flavor but maintains the detail, dynamics and everything the Premier does. The production of this fuse is very difficult, very hard to get the Beeswax into the fuse but the organic sound is too good to ignore.

Audio Magic Premiere SUPER fuse:
The Audio Magic Premiere SUPER fuse incorporates Audio Magic's anti vibration fluid to stop the element from vibrating at 50/60 hz and then the blackout powder super mix to absorb all EMI and RFI riding the element as well as ambient sources and insert a new HRC core which allows the signal to travel through the fuse in a more cohesive and linear manner. The Premier SUPER fuse is 30% better than the Audio Magic's original SUPER fuse in every way!