@ozzy What makes you think I'm "getting carried away"?
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.
https://verafiaudiollc.com
Showing 37 responses by gladmo
@wig Thank you sir! I do feel that my closing comments are true. Looking forward to hearing from other who are using them. |
@thyname Always nice to hear about people enjoying my writings. I’m a financial markets trader and investor, so identifying risk/reward, knowing one’s own tolerance for risk, and making moves is the one thing I do all the time. I've done well being an early adopter. Seeing some detailed descriptions about what testing went on during the R&D phase would certainly add to credence regarding reliability. In lieu of this, so far anyway, my decision was therefore based on general evaluation of the likelihood that everything that’s been claimed is actually true, including thoroughness of testing. In other words, going with my gut. Time will tell. |
Although my use of "headroom" to describe the sound quality still seems apt to me, I also think it might be something closer to "legroom" that needs a mention here as a way of looking at the mechanics behind this. Haha! Legroom 🙂. I mean like all of the inner electronic parts being lifted up off the floor from an operational energy deficiency vs having been relieved from pressing up against a metaphorical ceiling in a state of energy excess, where clipping and distortion occur. In either extreme state, there's distortion. I can't say with any technical certainty about any of this because I'm not an electricity expert, and that's fine with me. It's just the audiophile buzzwords that count, right? 😁 |
@tksteingraber Generally, I would say amp first. A little hard to say what order would come next, but I’d guess DAC, then streamer, then preamp. But my preamp has a patented power supply technology that runs on only a tiny fraction of the power that typically preamps do, so I think it’s performance was less restricted by fuses to begin with. So maybe preamp before streamer if it has a higher rated fuse amperage? @gnu I only posted the review here. If I were running that website, I would place the product description above a long review like this on the product webpage. Just my opinion though. @audioman58 I can only share that the user manual has a warning not to use the slugs+device in place of an amplifier’s DC rail fuse if there is one. Regarding oxidation, after polishing my copper Sluggos with a gold jewelry polishing cloth they sound different, more neutral and less warm, and at the time it seemed like an little increase in detail retrieval too, but you can’t go back to A/B. I wouldn’t mind having backups of each slug which haven’t been polished because I’m a tonehead. The sound will probably very slowly shift to warmth as oxidation occurs. @verafiaudio Good morning, you’ve got my attention with those new Sluggos 👀
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@verafiaudio Mark, I’ve got a question. It’s been awhile since I’ve read all of your comments on other forums, so I’d like to clear something up about what I recall less than perfectly. If, for some unexpected reason, the active parts on the circuit board fail (microcomputer, whatever else could potentially fail due to defect or something) while it’s in use, can charge still flow through it? Or is the relay method one that is passively closed and blocking charge from flowing if the active electronics were to malfunction? |
@verafiaudio I really appreciate all three of those responses. Your answer to my question is brief, but that statement is what I was looking for. I admit that I don’t understand much about relays and the related terms. I just found that I actually have a spare pair of unpolished large copper Sluggos for my amp, so I’m going to see how the system sounds with those in place of the polished ones that are in the amp now. A normal type of daily activity for me 🙂 |
I didn’t have any communication with Walter at Underwood HiFi, but nothing about him copy/pasting my review bothers me. I don’t feel cheated, stolen from, or anything like that. He’s selling this device as a type of partner with Mark of Vera-Fi Audio. I’ll allow it, no worries. Linking here was a good move. I did speak with Mark on the phone a couple times while I was trying to form a buying decision because I had questions about the two different fuse rating in my DAC, etc. He was super helpful and I got an honest and cordial vibe. |
Switching to unpolished copper slugs in the amp and keeping polished copper slugs in the other three components is really nice. Gonna keep it this way. A little more body, warmth, and low end, and slightly less relative energy in the top end, as expected. There's still the same presence of subtle ambient cues and reverb that I was checking for. Very cool. |
@vandy357 That all sounds right, but I can't be totally sure about your amp fuses. You can call Mark at the phone number on the website URL I gave at the bottom of the review and he'll get you sorted out. |
You can just use stubby little Nema 5-15p to IEC C13 adapters to connect the fuse box to an outlet. They sound good in my application. You may or may not need some extra support at the outlet with this method because of the leverage the weight of the device will put on the adapter’s connecting spades. Vera-Fi Audio also makes 1-ft mini-cables you can try using. It’s a $395 upgrade for each component. You’ll get enough Sluggos included for the fuses that are replaced. My DAC and amp both use two Sluggos. I wasn’t charged extra for those. @vandy357 given Wig’s post just above yours, I’m not sure what your concern about the amp is. Just leave the DC rail fuses where they are. |
My pleasure to help, guys. For anyone that is using SDFBs, I ended up switching back to the polished copper Sluggos in my amp after a brief time with the unpolished ones. It became apparent to me that, actually there is some small loss of fidelity due to the oxidation-based corrosion on the unpolished Sluggos. My recommendation is to go for polished Sluggos with any SDFB you have installed.
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@lalitk They are basically the same adapters that I mentioned briefly in the review. I'm currently using one on all four of my SDFBs. |
@tweak1 It 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! You'll get it resolved. There's always a way! |
@tweak1 You’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. |
Well, it's an extremely simple test that anyone can do themselves. Unempirical speculation isn't really necessary. |
@thyname, @wig and 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. |
@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. |
@recklesskelly I totally respect your position on fire safety. Everyone should have a capable and charged fire extinguisher. @thyname Looking 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.
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@verafiaudio Generous policy! Love it. I have a new preamp in the works, so this is good to know. |
@lalitk I 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. |
@lalitk Actually, 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. |
None of this undergrad academic credential jockeying has anything to do with the actual sonics of replacing fuses with slugs by using SDFB. Purely based on the same stubborn pattern repeating without end, it appears Jason was Bourne to be an internet troll feeling desperate to be perceived as the superior intellect, regardless of experience. Basic business reality and profit margin doesn't seem to click either. |
I've used 4N silver slugs and the sound just wasn't for me. Pretty much what I expected though, as I've never found all silver conductors in power cables or in signal cables with the analog section of my chain to have a desirable tonality. I do use all UPOCC silver conductors in my two Ethernet cables, though, and absolutely love them. |
I think you'd be very surprised how transparent the extra short AC adapters we are using are. To me, they are sonically undetectable. And any remaining tiny bit of coloration or electrical resistance coming from the wiring in the Fuse Boxes is overwhelmingly outdone by the sonic improvements from swapping fuses for slugs. |
@kennyc Thanks for the comment. I’ve added two more and now have six units. Rythmik subwoofers adore these things. I’ve never seen any reports of users saying something like "no thanks, didn’t hear a difference". In my system, every one of the six was an eye popping improvement. |
@johnnycopy I have two Rythmik subs, both with SDFBs and the power cables that connects them to the subs are Vogue Audio 11ga UPOCC silver, which I changed out the connectors on. The SDFB’s have the largest impact on power and speed, but I think this particular power cable is the best you can get for a subwoofer. The large guage UPOCC silver has the deepest sub-bass and most linear bass response for these subs of anything I’ve tried. I’m not a fan of them in most applications, but for subs they are the cherry on top. |
@bsavage Thanks for sharing. Your SDFB journey was very similar to mine, and I think you are describing very similar qualitative changes as I tried to articulate in the original post, just with a few different words. I hope my post inspired your journey that turned out so well in the end.
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