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.
@jasonbourne71looks like you went ot Uconn with my brother. He got a PhD in English literature, not much more useful than your 2 years w/o a degree. But he is a professor now, teaching other people about 600 to 800 year old plays.
I have some experience with SCRs in superconducting magnet power supplies. They weren't terribly reliable but I have one cut in half for forensics around here somewhere. An SCR crowbar is an overvoltage protection circuit. we are looking for overcurrent protection. Good try....no, not really.
Using a breaker to replace a fuse is not patentable. I could develop my own flavor and go compete. (not a threat, I'm too busy with my day job and modding my system). It is pretty easy to understand how this works: jumper the fuse and insert a magneticly tripped circuit breaker. They say they adjust it to trip at your desired current although it would surprise me if a small breaker like this is adjustable so I'm guessing they use a bridge circuit or something similar.
The setting isn't that critical. Most manufacturers wet their finger and hold it up in the air to pick the size fuse they use. and here's a dirty little secret, one reason the expensive audiophile fuses sound better is because they pass more current and fail at a higher value. Note this is different than your home protection breakers which are sized for the wire in the circuit and should never be changed without an engineer's help. this type of sizing isn't possible for an exlectronic component.
@thyname: No, I was a math major in college. Though I have always been interested in Mechanical Engineering and Material Science. Plus I am an excellent draftsman!
@thyname: That's the fault of the Agon programming! It only allows one email per name. When I tried to use my other emails I always got stuck in a loop - "user name taken" and "email incorrect"! Back and forth! So now I sign in using Facebook.
If the SDFB is not patentable then it has been around awhile. Anybody here with an EE degree willing to discuss how it works? Or do I have to go over to the DIY forum?
@carlsbad2: Look up "scr crowbar circuit" on Google. I'm surprised you don't know about it! It does work instantaneously! I am curious what exactly is inside that $395 box? Micro processor Hall effect - yeah? If I had a peek I could copy it and go into business! Apparently the circuit is not patentable!
@jasonbourne71I usually ignore you since you are farther toward "nothing matters" than those you criticize are toward "confirmation bias". as with most things in life, the answer is in the middle and you’ll never find it locked into one side or the other.
Since you addressed me by name I’ll reply. You ignore how much a fuse degrades the sound. As I’ve posted earlier in most cases I evaluate the risk and replace the fuse with a slug achieving even more than the SDFB does.
I have worked 40+ years at a power plant where I’ve been responsible for thousands of very high end breakers as engineering manager. I’ve been looking for and even challenging my electrical engineers to find a magnetic breaker that I could apply like this. I was going to make mine slip into the fuse box...as you can see there is an emotional resistance to putting a slug in a fuse holder, even if there is a breaker 2" away.
But this guy beat me to it. and while I did criticize the price, and I would never have picked such an oozing-with-marketing sounding name, this is not expensive for high end audio equipment. I’d say his markup is less than the high end calbes you don’t believe in.
I’ve never heard the SDFB in service but if the magnetic breaker he has found provides a high current, resistance free circuit (unlike fuses or thermal operated breakers which use a high resistance bimetal strip in the circuit) then I think this will provide about as much bang for the buck as any upgrade you can do (short of my slug-without-breaker mod).
This device is only for the IEC/AC line fuse. It is NOT for the B+ DC rail fuse/fuses! Apparently some here don't know this! So even if the SDFB is installed your component will still have power supply fuses in place.
@thynamehis other moniker @jasonbourne52is still active, no conspiracy here. Could have a new device and forgot his password. You can look up servers and find out if they have been banished.
@recklesskellyI'm certainly not trying to argue. I'm sure you saw my post of fire above and I know not everyone will agree with me.
Here is my skeptical viewpoint on what the investigator blames a fire on: they sift through the ashes, and can find very little. they look for anything out of the ordinary, something that survived the fire. they often find something that looks like it wasn't to code and often blame the fire on that, without any more evidence. and that certainly wouldn't hold up in court. but insurance compaies love to settle.
They also ask the homeowner if they have modified any equipment or strung too many extension cords together, etc. Sometimes they blame the fire on circumstail evidence if the homeowner says, "well, I did have quite a big cluster of wires under my desk, I guess I shouldn't have done that."
Sometimes they can conclude the area of the home where the fire started--the kitchen, the laundry room, etc. If they determine it started in a stereo rack with 12 components in it, they won't be able to point the finger at a fuse. I really doubt buss has ever been sued.
But I don't think you want to get there. Perhaps you meant to ask, "Can you convince me my house won't burn down as a result of this breaker?"
Here is the situation I mentioned: I bought an amp that uses EL84 output tubes. I have another amp that uses 6P1T output tubes. In a moment of mental unclarity, I somehow thought thew were interchangeable. It turns out that the pinout is different and the 6P1T provided a direct short across the power supply to the heater. I put them in and no music came out. I smelled smoke and turned it off. Put the right tubes in and it made noise for a few seconds and then went quiet. I opened it up and found a smoked resistor. Cost me about $5 for a new resistor and 10 minutes to install it. I'll attach a photo of the 3 fuese that this amp uses to protect the output transformer. None of them blew. I'll also attach a photo of the current configuration of these fuse holders. I gurantee they sound as good as a digital fuse box.
And I hadn't seen the ones without the pigtail. I undertand why when you've put $5k into a power cable, you don't want to add a new cable between it and your amp. But the fuse is a tiny little resistor that limits current. If I could afford a $5k cable (well, I guess I can, haven't chosen to buy one) then I would probably just put a slug in the fuse box and replace the amp if it fails...but I don't know what amp is in play here. Truthfully, it is very seldom that an amp fails in a way that blows the fuse.
Finally, I really don't have a problem agreeing to disagree here. I fully expect to be in the minority. I've lived there my entire life.
@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.
@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.
@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 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.
@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.
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
@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.
@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.
@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.
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.
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!
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!
@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.
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.
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…
@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
“We are in process right now with developing new and more "advanced" Sluggos.
This includes materials - and "treatments" . Some pretty exotic variants are coming”
You must have a verified phone number and physical address in order to post in the Audiogon Forums. Please return to Audiogon.com and complete this step. If you have any questions please contact Support.
