Swiss Digital Fuse Box - "What headroom sounds like"
Swiss Digital Fuse Box (SDFB) is non-sacrificial overcurrent protection device that serves as a replacement for fuses in audio equipment.
There are four devices in my sound system that I’ve replaced fuses with the SDFB, and its transformative capacity to upgrade sound quality beyond that of fuses has compelled me to write a review. I’m not associated with Verafi Audio, the company that sells them, nor did I receive anything from them as "review units". There’s another thread on Audiogon about them that an audiophile friend referred me to, which got me interested enough to buy them. I am now enamored with the sound of my system in its current state, so I wanted to share my take on one of the more significant steps in how I arrived here.
Before getting into details about its form and function, I want to share my impression of what the Swiss Digital Fuse Box (SDFB) does for sound quality. It makes my components sound like they are operating without any limitation of power. It sounds open and unrestricted across the audio frequency spectrum. The sound is dynamic, detailed, defined, and there a sense of harmony and completeness about it. It’s like my components can now output their full frequency and harmonic potential.
A few things about me... I’m more of an artist than anything. I’ve been a music lover for 35 years and an electric bass player for 15 of those years playing in two bands, with which I was the bass player on one full LP recording and one EP. I’ve recorded, mixed and mastered my own multi-layered solo bass recordings and their backing tracks from sampled percussion using digital audio workstation software. I’ve also fine-tuned two of my custom car audio systems using DSP software and built, tweaked, and tuned a high end home stereo system (yes I said *tuned*, without using DSP) . Given this experience and the resultant development of a keenly perceptive and informed "ear", yet having no formal electrical theory or engineering background, I feel comfortable suggesting that the results of using SDFB can be likened to how audio sounds when the device producing it is operating with ample headroom. What does headroom sound like? The term headroom has different meanings in its use within pro audio recording/engineering and electrical circuitry operation, but they are related in a way that the end result sounds uncompressed, undistorted, fully dynamic, and expresses the sense of the effortlessness of unrestricted flow.
Does this sound like embellishment? It probably does. And I haven’t even mentioned the typical audiophile terms like "inner detail", "layering", or "rock solid imaging", nor have I even mentioned soundstaging attributes yet -- even though all of these qualities have also gone through upgrades due to the SDFB’s being installed. Am I merely in an irrational, excited state because my whole system now sounds much more expensive than it is? I don’t think so. I’ve been using all four SDFB units for three weeks consistently, and the initial excitement phase I was experiencing settled at least a week ago. I also think that the more components a system has which have replaceable fuses, the greater the potential upgrade from replacing each of those fuses with SDFBs. Like I said, I replaced all fuses in four of my audio components (six fuses in total), and there were notable step-up improvements in sonics as I progressively installed each of them.
Now I’ll describe the physicality of the device and how to use it. Then, I’ll try to describe specifics about why my previous fuse setup, which was a combination of Synergistic Research Purple and Master fuses, was completely replaced by SDFBs. These SR fuses were already a major upgrade in sound relative to the stock, generic fuses, and the SDFBs transcended the SR fuses in every discernible way.
These things have two separate parts that work together: 1) a small box that is inserted as the middle of a chain created between an audio component and the electrical outlet from which it draws power, and 2) a solid, cylindrical metal slug (referred to as a "Sluggo") which is the same size as the typical fuse. To install a SDFB, first, with your component off, plug its power cable into the AC socket on one end of the box, and on the other end of the box there is a male IEC connector (C14) which you connect to an outlet using another power cable or an adapter. I’m using a combination of two short, homemade mini-cables, and two generic adapters with my four SDFBs for the best sound (details shared in my Audiogon virtual system). Once the box is connected to a live electrical line, it will go through a brief setup period, and after maybe 8-10 seconds, you’ll hear a clicking sound and the small green LED will stay lit, indicating that charge is now allowed to flow through the box. The second and final step, with the component still off, is to replace the fuse(s) with a Sluggo. The device comes with both copper and brass Sluggos. You can then turn the component on. Don’t replace a fuse with a Sluggo without the SDFB in place because you’ll have no overcurrent protection and you’ll incur the risk of severely damaging your component and/or having a catastrophic fire in the even of a short circuit or other overcurrent scenario.
These units monitor current magnetically, and are calibrated to whatever fuse rating is needed when you order them. They are also calibrated to operate as either slow blow, or fast blow, like a normal fuse. When the set parameters are exceeded (too much current), a relay is switched to the closed position and charge is halted from flowing. Being non-sacrificial, you don’t need to buy a new one, you just unplug it from the outlet for about 30 seconds and it will reset the state. Then it can be plugged back in and reused. There’s no damage done to the device due to the overcurrent condition, unlike a fuse which melts due to high heat. Currently, devices being produced are to be calibrated at 10 amps max, so if there is some crazy high current event, perhaps then it could be damaged. I don’t know. I believe that’s pretty unlikely though. I think I remember reading that there’s a 15 amp version in the works.
There is some inconvenience involved with transitioning to SDFB due to the extra weight of the box (not that heavy, really) and extra length added to the power chain, as well as potentially requiring additional investment in more power cables. I feel that I achieved an optimal result for only about $200 of additional investment by using some DYI cable materials I had available, some high quality plugs to terminate the cable with, and some cheapo adapters from Amazon. For me, dealing with the extra weight and length to the cabling and putting in the work to create the best solution for connecting the SDFBs to my power conditioners has not been a big deal compared to the profound jump in sound quality. Totally worth it.
Before I went all SDFBs, the best configuration I found with SR fuses in my system was one small Master fuse in the LPS that powers the modem and router (I have an all-digital streaming system), two small Master fuses in the DAC, one small Purple fuse in the preamplifier, and two large Purple fuses in the amplifier. It’s worth mentioning that total retail cost of this setup is about 33% more expensive than the retail cost of my final SDFB setup. However, if you choose to buy a bunch of new, expensive power cables to connect your SDFBs, that would quickly become more the more expensive option.
I thought the SR setup sounded great at the time. I was impressed with the top end detail that a few of the Master fuses added to the fuller midrange and mid-bass sound of the Purple fuses which I already had. I’ve seen comments from others on this site in agreement about this. This combination is getting some praise. However, when comparing that sound to the SDFB sound, it was like the SR fuses are stuck at a level of trying to boost certain frequency ranges to make up for how restrictive a fuse really essentially sounds.
How do you improve on a small, low resolution, blurry, drab looking photo? Well, you manipulate it in Photoshop, of course! You try to crank up values of various visual (light-based) metrics to make it more attractive. However, that process will never produce something as close to the original subject as when you start with an ultra-high resolution, high-dynamic range photograph. You can’t "add resolution" to something that is intrinsically underpinned to a state of reduced resolution. To me, this is analogous to the task of starting with the tiny, resistive piece of wire in a fuse and trying to add crystals and various substances of specific resonant frequencies inside and around it to end up with something representative of the innate completeness of the source material.
Comparatively speaking, I was surprised to switch back to the SR setup and find that the soundstage was compressed towards the center. It was like there was a somewhat spherical haziness in center stage from which the sound was straining to emanate from, even with the Master fuses in play. I attribute this sense of "haziness" to a combination of reduced dynamic range, and a distortion of the frequency response coming from the system’s components. If the hypothetical ideal response for a natural sound (assuming the important aspects of room acoustics and one’s hearing quality are held constant) is essentially a linear response from top to bottom in both amplitude and purity, then the sound of the SR setup was now perceived as distorted and a deviation from linearity.
The sound of the SDFB setup is far more natural, far more detailed, and imparts a sense of ease while listening. I’m using all copper Sluggos, as their tonality is more natural to me than the brass versions. The soundstage has opened up with more dimensionality and all of that perceived haziness and limitation of full expression is (seemingly) completely gone. Images became more defined and image positioning is on a more advanced level. I can now perceive the two singers positioned near center and side-by-side in the mix, with a gap of about about a head’s-width between their mouths. This wasn’t perceivable with the SR fuses. The positioning of cymbals on a well recorded drumset are precisely locateable in space. Listening to Russion choral music, I can now hear individual tenor and bass voices and their unique tonal qualities. On one excellent recording of a solo harp, there’s beautiful overtones resonating that I’ve never been able to hear before. The sound is descriptively harmonious.
Over the course of a couple weeks, the sound of these units opened up. To begin, there was some minor coloration of the sound, but I’m not sure I can hear it any more. I think most of it has gone away as the units have burned in. Even with the minor coloration in the beginning, the immediate leap above the SR fuses in sound quality was obvious and highly desirable.
One last thing, I did a rough test of the overcurrent protection functionality, as this is obviously a major thing to get right and have working properly. I’ve been told that most refrigerators pull about 1 amp of current, so I used that as a basis for testing since I don’t have any more sophisticated method (I could use my desktop computer PSU which has a wattage display to achieve more accurate testing, but I’d rather not have its power suddenly cut and risk problems). I have two SDFBs calibrated to trip at levels below 1 amp, and two units calibrated at significantly above 1 amp. With each of the two sub-1A units inline with the fridge’s power cable (doing two test rounds for each unit), they immediately tripped and the fridge’s power was disconnected when I plugged in the power chain into the outlet. For the above-1A units (also did two test rounds each), the units did not cut power, and the fridge turned on and operated normally. I feel like this testing demonstrates enough for me to have a boost in confidence in the overcurrent protection operational integrity.
Being able to safely use solid metal slugs in place of fuses is wholly a paradigm shift in a high end audio system’s sound quality potential. These things deserve attention and I’m grateful to have been pointed to them.
@tweak1It could actually be a good thing, meaning a more capable top end from upgrading, but elusive room acoustical properties can give the extra high frequency energy an unnatural or unpleasant ring. When I went through several sound system improvements back to back, I ended up with a hot top end, but there was an easy way to balance it. I had three SR wide angle HFT units sitting in my tubes and accessories storage area, and I put them on the front wall high up, about 9 feet from the floor. One is in the center and the two nearer the side walls are about 9 feet from each other, and at the same height as the center one.
Just this one thing smoothed out my top end by effectively neutralizing high frequency reflections in the top half of the room. The product is sold with a 30-day return policy, so worth a try.
At this point I'm like an self taught expert on how to use them and another acoustic treatment product called Holostages 😁 Maybe that sounds pretentious, but I do have a desire to teach others about what I've learned and discovered.
Even though I choose to have a 77" TV on top of my audio rack, which is centered in front of the listening position, I have been able to achieve a nicely holographic three dimensionality using these techniques in a specific arrangement around the room. The soundstage depth is now only suffering a little bit, whereas without them, the depth is pretty squashed, even though height and width are fine. I'm thinking of writing a whole, long piece on what I've learned about these methods... but the work involved and the inevitable counterforce from skeptics of non-axiomatic methodologies are a little off-putting to think of!
@tweak1You’re welcome, and if you end up going this route I’m open to help with getting it right. I don’t want to go into details here, but there’s certainly technique involved in tuning it, taking into account room size and shape, etc. The wide angle HFTs can pretty easily be overdone, so for a small room the regular HFTs could work better.
Of course, there’s traditional acoustic treatments for the upper part of the room, but they are typically more expensive, much more difficult to install, and not something you can move a few inches this way or that way, again and again, to get it to sound just right.
@thyname, @wigand other SDFB users: I found out today that, whether or not you’ve polished your Sluggos, wiping them and handling them only with a clean, fine fiber cotton cloth when inserting them into your fuse holder is very important for high frequency response. Touch them with your oily fingers after cleaning or polishing and your finer detail resolution and HF response will degrade. Handle only with your cloth and listen for better resolution! Cool, huh?
The best is full polishing with both sides of a Connoisseurs gold jewelry polishing cloth, then clean with 99% isopropyl alcohol using a microfiber cloth, then insert into fuse holder, all without skin touching it. Maybe wear nitrile gloves, or just handle with the cloth. Crazy good details. I can hear sounds of the wiping of fingers along guitar strings. Incredible.
You may be into something here @gladmo, thanks for sharing. I have not had any chance to experiment with polishing, or even trying the brass sluggo, as I have been very busy at work, but I continue to be amazed by the impact that the Swiss Fuse Box has in my system, even if used on only one component of my simple system.
@thyname I got the polishing cloth idea from someone else's comment on a different internet discussion forum. But once people start trying the whole process I just described, I'm sure it will become the standard. Order the cloth and find the alcohol; I'd love to hear your report. Yes, I'm using Sluggos in a number of different components, but I'm certain you'll like the change just in your single component.
I finally got around to trying the brass sluggo today. Before I inserted it replacing the “untreated” copper sluggos to my Innuos ZENith, I polished the brass one, the whole procedure @gladmoshared, jewelry clothe, isopropyl alcohol 99%, handled with surgical gloves. Been playing for a few hours now. Hmmmm… I think I prefer the untreated copper, although still sounds fantastic, not much difference. Next weekend I will polish the copper sluggo, same procedure, before reinserting it.
Also, I look forward to the new sluggos Mark @verafiaudiowill have available soon!
Take it with a grain of salt @thyname as I am an Electrical Engineer that also worked at UL in Northbrook Illinois (UL Lab) and I am on the NFPA board, call your (write federal fire codes) insurance and have a B:C rated fire extinguisher near by. Fuses are in your system for a reason slick, even the purple and orange fuse blow with a circuit overload.
@recklesskelly I totally respect your position on fire safety. Everyone should have a capable and charged fire extinguisher.
@thynameLooking forward to your untreated copper to treated copper comparison. Personally, I never ended up sticking with any of the brass slugs, whether treated or not.
So, I just purchased some .9999 7-gauge solid silver rods. I may need to solder 2 of them together, but my intention is to use it in place of the copper slug.
I had chance to swap in the freshly polished copper sluggo just a few hours ago. I can say with certainty that I prefer the copper sluggo when compared to the brass one. The difference is audible. I can see some may like the brass one more though, and I can understand why. Of course, this is a matter of personal preference. They are both similar, and the respective use of each does NOT diminish the surprisingly good impact of the amazing Swiss Fuse Box.
In terms of polished vs. not polished, I cannot really tell much. Maybe my ears are not sophisticated enough, or maybe because there is only one of the three components in my chain that has the Swiss Fuse Box.
@ozzy: outstanding! Please let us know your impressions. I did think of the possibility of a solid silver sluggo as an option, and I was guessing (in my mind) that was probably what @verafiaudiohad under his sleeves as the new sluggo yet to be distributed. Thanks!
@gladmo@verafiaudioI'm confused about how the Swiss Fuse Box gets set for the amperage and slow vs fast blow? On their website there aren't any options during the ordering process. Is this user settable or do they contact you after ordering?
We require direct feedback with this end user at this time. We make absolutely sure that we are programming your SDFB to precisely what is required. In many cases, we even double check with the manufacturer.
Once we have the data... we program, burn in and then ship.
Everyone associates fuses with fire. that can be the case but not usually. Fuses can be implemented for 3 things:
1. Fire protection. they are required by codes for that reason.
2. Equipment protection.
3. Financial protection.
Most fuses in stereo equipment are for the 2nd and 3rd reasons. Fire protection is the primary function of the breaker panel at your house, protecting wires from overheating in the event of an overload. These wires run through the walls where there is lots of fuel for a fire.
Stereo equipment fuses are almost always put there to protect the equipment. There is no fire loading (fuel) in an amplifier. In the event of an overcurrent situation a component will fail, there will be puff of smoke, and the fuse may, or more likely may not, blow.
Now why are fuses bad? Fuses by their nature limit power. We buy 100 lb power supplies and 10 awg power cables, then we strain all the power going into our amplifier through a filament the size of a human hair. would you put a tiny resistor in series with your power in to your amp? Well that is what a fuse is.
I am an Engineering Manager at a very large facility and have discussed this at length with my fire protection engineer who is highly respected in the industry. He agrees there is no fire danger inside an amp. If there is any fire danger is is likely the unexpected failure of large caps and fuses do nothing to protect against this.
So I know I’m not going to change many minds with this post and indeed, everyone has their own risk tolerance. Most people were told from age 3 by their mother that if you put the wrong fuse in a holder the house will spontaneously combust and that mentailty isn’t going to change reading an internet post. So if fuses make you sleep better at night, indeed keep them on their pedestal. But fuses always degrade sound. Most people just accept that and that is ok.
I have been following this thread with a lot of interest, you see I am one of the people who bought into the Swiss Digital Fuse Box, some of you may think I am one of the fools that bought into it but that’s OK. When I installed this device into my system, I hooked it up to my amp, on the first listen I could immediately tell a difference, I didn’t have to guess at the difference because I could hear it. It seems to me that one important thing about the SDFB in recent posts has been missing, that is the fact that you are not removing the protection that the fuse being replaced with a sluggo provides, you are just shifting that responsibility to the fuse box itself which contains a circuit breaker or relay that is set up to the specs of the component you want to install it in when you order it, as in fuse capacity and whether it is fast blow or slow blow. I think the whole premise of using such a device is the fact that current from the wall will flow easier through a circuit breaker or relay than it will through a thin wire inside a fuse. If there is a fault in the electrical circuit the relay should open providing the same protection that the fuse offers, once the fault is corrected the circuit breaker/relay should stay closed once again letting the current flow without having to replace an expensive fuse if that is what you have in your component.
This fool is so sold on this thing, I will eventually end up installing these in all my components. Next up will be my PS Audio Direct Stream DAC MK2. Thanks Mark and @gladmo for all your help!
“We are in process right now with developing new and more "advanced" Sluggos.
This includes materials - and "treatments" . Some pretty exotic variants are coming”
@lalitk: the type of the sluggo has no impact whatsoever on the settings of the main unit, the fuse box. The sluggo is simply a piece of metal that replaces the actual fuse inside the unit. The fuse box is the actual “fuse” so to speak, programmable for either 1) slow or fast burn, and 2) Amperage. The sluggo is simply the size, small (20mm by 5mm) or large. That’s all.
I have no idea in the price of the new and improved sluggos, but I would assume not much. The fuse box itself would remain unchanged, and that’s where the majority of the cost is IMO
Your post was a welcome birthday present – thank you for that.
This is just Audio and it should be fun – it’s that here, and I’m still enjoying myself.
Appreciated your perspective…
@ozzy
Well spoken and well said. We are all just trying to eek out all we can from our systems.
I learned long ago that everything in the chain matters. EVERYTHING.
Those that want to be exposed visit and enjoy the space here. Glad for people like you…
@vandy357
Enjoying right along with you. I think that too often the point is missed – lets get all we can from our huge investments here. I’m doing that – and I’m really pleased with the results.
@lalitk
To be candid – I’m not sure yet. Won’t be a fortune as that goes against my personal goals for this product and just in general how I view the INSANITY that’s going on with prices
I am aware of several people developing Sluggos that are REALLY Cutting Edge – can’t say what how much these might be – but again, not silly sauce money. M
@thyname
You have it exactly correct in both areas. Thanks…
Last night, I found that the SR blue fuse in my EAR 864 pre-amp sounded more closed in that an SR purple fuse (both having 100s of hours on them) but the purple fuse, despite being more open, slowed the pace/dulled the rhythm-less interesting (yes I also flipped their position). I installed my back-up new Acme fuse (with special coating). Immediately, it sounded faster, much more open than the purple. I tried the same with my EAR 890 amp Same result. It took two hours to calm the Acme fuses down (increase body, decrease thinner sound).
However, in my DAC, only the purple fuse sounds great (don’t have a blue or orange to compare). The Acme is just as terrible as the stock glass fuse, bright/thin and annoying. My friend uses a Hi-Fi tuning fuse in his DAC and it also sounded excellent.
I am very reluctant to try an SR master fuse except in the DAC at this point. The Acme put more string sound on stringed instruments, more air/open sound, faster pace while delivering just the same full body and dynamics of the SR fuses EXCEPT in the DAC.
@fleschler: it sounds like you affluent with swapping fuses in your equipment. You should give the Swiss Fuse Box a shot! You may be surprised what it brings to the table.
This thing is just an SCR crowbar! It is made of four parts: a silicon controlled rectifier (thyristor), a zener diode, a resistor and a capacitor. Cheap and easy to build! Put it in a fancy case and charge hundreds to unsuspecting audiofools!
Even considering the part count I doubt it sounds any different than a fuse. Spending money for a nicely encased circuit board with a catchy name sure stimulates confirmation bias!
Thank you both for the clarification. I’ve yet to figure out how I am going to implement a SDFB as the receptacles in my Mr. T are in very close proximity with one another. Implementing SDFB means sacrificing the use of next outlet. And I don’t want to use another pigtail PC in the signal path of my $5K HIJRI PC.
@recklesskellyHow much product liabiity do you think Buss assumes for the 99c fuse that this breaker replaced? Breakers are not new or different. Not sure why this one is attacked other than fear of the unknown. I guess people don't understand that you can jumper your fuse if you move the breaker 2" upstream in the circuit.
Now I think it is way overpriced. It is a $30 breaker in a $50 box selling for $400.
@vandy357Don't expect nearly so much improvement or maybe none at all from low power equipment such as DAC, streamer etc. Fuses have much less detremental effect when the current is very low.
@carlsbad2as Bussman Fuse is owned by Eaton a multi BILLION dollar company that is in multiple business segments I will bet $1 million per incident. I get that it was a snarky question dripping with cynicism . I have no fear of this product as it would never enter my home, as I value my families lives and our property, more than well this nonsense of limitless headroom. I only fear for the folks that have not given this one thought. If Eaton made this there would be NEC, UL and TUV certifications as well as ASE validations.
I’ve yet to figure out how I am going to implement a SDFB as the receptacles in my Mr. T are in very close proximity with one another. Implementing SDFB means sacrificing the use of next outlet. And I don’t want to use another pigtail PC in the signal path of my $5K HIJRI PC.
Ah…If no spare outlets in your power distributor, maybe you should reconsider the use of a pigtail power cord, or even a short length power cord you may have laying around. Your Hijiri power cord would be connected at the leg going to your equipment, so I think it should still provide the goods to that component. Needless to say, there is so much we are willing to put up with little conveniences in our implementations. Sometimes something is too much to deal with, and we stop. I have been there, many times, so I certainly relate
@recklesskellyYes they are a big company but next tie you have a component fail and the fuse didn't blow (I just had this happen last month) call buss up and tell them you'd like them to pay to fix it.
@lalitkI don't understand your problem. the box has a short pigtail and will plug in where your current cable plugs in. then your current cable plugs into the box. Now putting this box in series with your $5000 cable strikes me as a head scratcher but don't know what to do about that.
@carlsbad2I understand your position, but if my house burns down because a buss fuse fails and the investigators determine that it due the fuse, I stand a better chance or my Insurance stands a better chance of recovering losses than any one with this device.
What was the root cause of the voltage/amperage spike that the fuse did not protect your equipment from? What did it cost to fix? Not that this has any bearing on the conversation.
And not all these devices come with a ’Piggy" tail, you order with or without. His point is not adding a link in the chain of his $5k power cable. Just like I would not plug one of these things into my $10K Integrated Amplifier and my $650.00 power cable.
@lalitkI do understand your issue. I might be able to help figure it out. Of the six outlets in your Mr. T power conditioner, are there any which are unused? Which locations?
Also, if you can tell me the distance horizontally between the centers of the three duplexes, that would help.
@lalitkActually, on second thought, I don’t think any of that matters. Regardless of which outlets are used, I think that you can use short NEMA 5-15p to IEC C13 adapters and expect to fit at least three SDFBs in a "V" shaped orientation, where there are two at the same height on the outer duplexes and one on the opposite vertical position in the middle duplex. Potentially, you could use four with all of them being on the outer duplexes, but they would be pressing against each other angled a little unnaturally.
The reason why the V shaped pattern will work is because the adapters' length will position the SDFBs just past the AC plug bodies of your other cables.
Either way, you’ll still have the joy of your Takumi PCs.
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