What is the science behind audiophile fuses?

@mitch2 nice clean job. Looks great

@mitch2 beautiful clean install.  When i do something like that, the more work it is, the more rewarding it is afterward.  If those breakers really are purely magnetic, they are better than any fuse.

Great job.

Jerry

@carlsbad2 - I finally finished installing the two magnetic breakers/switches that SMc Audio sent me to replace the fuses in my SMc amplifiers.  Each switch powers one of the two outlets on the duplex that the monoblocks are plugged into.  See pics right after the first picture on my system page.

Had I known how much work that was going to be, I might have simply purchased two SDFBs.  My 1/4-inch copper rod arrived yesterday so just in time to make two slugs to replace the fancy SR fuses that SMc Audio had in those amps - 2@ T10A.  I am giving it a run in right now and it sounds pretty good, but it did before too.  Certainly didn't make anything sound worse.  

@mitch2 Actually the Grimm MU2 does come supplied with an IR sensor.  You might be interested in downloading the software and hardware manual from Grimm's web site under the "downloads" tab which gives detailed explanations for volume control via Roon.  I also agree that Grimm should have provided a remote control, but I believe their intent was to operate from a phone or tablet via Roon.  I use both a tablet and a remote.  The software manual has instructions on how to program a compatible remote and the functions that can be programmed.  I went with a programmable remote provided by LTA (Linear Tube Audio) that they provide with their preamp for $50 which can be seen at LTA's web site in their upgrades category.  I've also programmed an old TV remote that I wasn't using but prefer the simplicity of the LTA.

@devinplombier - Thanks.  I believe the Grimm MU2 offers a jack for an IR sensor but not the actual sensor.  It just seems like a clunky solution for an $18K piece of electronics, in this era.  I will have to check out the Roon app volume control as I have never used it.  Still wish there was a regular remote control.  I wouldn't need one if it were just a streamer/DAC but since there is a preamp, it seems like a stupid omission.

@mitch2 

I think the Grimm has an IR sensor so one could use a programmable remote. Alternatively you could control volume via roon if you use that.

I hear you on trying to figure out what works. I am wiring them to the hot wire of the incoming 20A line with the two separate load side wires going one to each half of a duplex, that I will separate by cutting the tab between the two hot sides. The neutral and ground should be fine as-is since this is basically the same as wiring a switch.

If I decide to do something for the remainder of my gear, I will likely try the SDFB, and especially if I end up going the Grimm MU2 route since that will take the place of three different components for me and only require one SDFB. However, I am struggling to get around Grimm’s omission of a remote volume control and the inability of at least one reviewer to read the numerical volume level from their listening chair. I am far from lazy but not making it easy to change volume and read it while seated seems a huge oversight on an $18K component that is expected to serve as a preamp, unless there is an easy app intended for that purpose. I need to dig deeper.

@mitch2 I totally respect the value of intellectual property. that is why I asked it how I did. I didn’t realize you are working with SMc.

It is tempting to buy one of the amazon breakers and take it apart. but if inside I find a thermal overload (which I have found in most of the breakers I’ve disassembled), we won’t really know if it is the same breaker you have.

I toyed with installation of that style breaker designed to fit into a rack designed to accomodat it and it isn't easy to do it without quite a bit of construction.  Easy to hook up but you need to cover all conductors for safety.  

Best of luck,

Jerry

@carlsbad2 - I can’t for two reasons.

First, the manufacturer and model are being held close to the vest by SMc. They apparently tried more than a few before finding the one they believed sounded best with their equipment.

Second, in addition to their request for confidentiality, there are no manufacturer’s markings of any kind on the two breakers they sent to me. There is a T10A sticker that appears to be something the SMc folks use to label their stock and a "QC passed" sticker and that is it.

What I can show you is that the breakers look very similar to this, but they were much more expensive to me than the Amazon price indicated in the link. I had to give the installation some thought before deciding how to configure them, and I am now very close to doing the work (hopefully this weekend).

Of course, an audiophile fuse is not just a "straight wire." It's a straight wire within a sheath. I have to wonder if it is that interaction - wire in a very unusual sheath - that is involved in the sound results. Just for starters the fuse wire, which is very close to the component power plug junction, is probably being shielded from EMR effects.

@mitch2  can you share what make and model magnetic breaker you are using?  thanks.

Instead of using slugs and existing holders, why nor simply bypass the fuse altogether using a soldered link etc?

I would have used the 30A fuse in conjunction with the 10A magnetic breakers I just received and am working on installing.  Instead, I ordered 1/4 inch solid copper rod today, that I will cut in 7/8 inch lengths to replace my fuses for when I get the breakers installed.

It will surely be more conductive than your 10A fuse, as long as you don't end up regretting it. 

I wonder if this ABC-30-R fuse would be just as effective as a slug operationally and sonically?  This ceramic case fuse is 3x the capacity of the big 10A fuses in my amps and I suspect would be no more restrictive than the wiring connected to the IEC inside of the amp.

@carlsbad2 

Perhaps @lalitk meant a SDFB dongle that would plug directly into the equipment's receptacle, eliminating the extra power cable the regular SDFB requires.

@mitch2   Krell was using magnetic breakers over 30 years ago. I have a 20a breaker in my Krell ksa 300s, seems to work fine.

If you have a dedicated line to your amp, and your amp has say 6.3 amp fast blow fuses in it, would putting a low current 6 amp breaker in your panel do the same thing?

Panel mount: The issue is that a magnetic breaker replacing a fuse needs to be dedicated to a single the component, just like a fuse protects the component. OTOH, the breakers in your panel protect the line - i.e., a 20A breaker breaks when current on the line exceeds 20A at which point a single component might already be fried.

Fuse holder mount: The magnetic breaker is quite a bit larger than a fuse holder. If you are asking about retrofitting existing equipment the easiest method would be to use something like the SDFB. In looking at retrofitting my SMc amps, it would have required cutting a hole in the back plate of the metal case and then rewiring the fuse holder and IEC, all of which I was comfortable doing myself. The problem was having to move the main board and disconnect several parts to make room to perform the work and at that point it became easier, less invasive, and less risky to incorporate a solution that was exterior to the amp. SMc uses the breaker to replace a fuse in their new equipment, and in their upgrade work. However, the breaker requires a larger hole in the case than a fuse holder. The breaker can also take the place of an on/off switch as it does in my SMc DAC-2.

Exterior box mount: I believe the easiest DIY opportunities for existing equipment are either a separate external box (like SDFB) or perhaps mounting the magnetic breaker in a gang box or separate small breaker box wired directly to the power line feeding the duplex where the equipment is connected, which is what I plan to do. The key is providing one breaker for each piece of gear so every outlet would need to have its own breaker. My two amps are fed from a single dedicated 30A line and each have a 10A fuse. I plan to mount the two 10A breakers just in front of the duplex, with each breaker feeding one of the two outlets in the duplex. Each outlet will have its own dedicated breaker. The outlets in my Furutech duplex will need to be separated from each other by cutting the tabs on the outlet and then each outlet will need to be individually wired. The breakers are basically an in-line switch wired on the hot side.

@lalitk I don't think anyone is now working on a version that fits into the fuse holder.  I was the most interested in that and I've moved on.  Like I pointed out, every IEC fuse holder is different so very hard to make one that works on every amp.

@thecarpathian I don't think so.  but I'll give it more thought.

The breakers in your panel are a combination of thermal and magnetic.  The thermal component doesn't cause much problem because it is rated much higher so it doesn't act as a current limiter at low currents.  Lowering it to the level of your fuse would make it cause the same negative effects of limiting bass and dynamics. 

6.3A is a pretty big fuse.  You must have a big amp. If you have a big amp, with big copper coils and lots of stored energy, you may not benefit much from fuse changes or elimination.

Jerry

@tksteingraber

Thanks for posting the picture of SDFB.

@carlsbad2

It sounds like you’ve put a lot of thought and effort into addressing a concern from some of us. I am ok with slugs but don’t want a pigtail in the signal path so let’s see if SDFB would make a version that can be plugged directly into a component IEC.

@carlsbad2 ,    @mitch2 ,

You guys are light years ahead of me with this stuff and I have a question for you:

If you have a dedicated line to your amp, and your amp has say 6.3 amp fast blow fuses in it, would putting a low current 6 amp breaker in your panel do the same thing? 

Thanks @tksteingraber - the SDFB looks well made with heavy wire where necessary (except to the LED).  It appears to be a breaker with a small control board, likely for the automatic reset.

If I were to use one, I might hard wire a pig tail power cord to get rid of one IEC, but I make PCs so one more short cord is really no problem. 

@devinplombier I worked to develop a way to adapt the SDFB without an extra power cord and it isn't hard to do for a specific amp.  but every amp uses a different IEC receptacle on the back and every receptacle has a slightly different fuse configuration.  

So if you adapt the SDFB to plug into the fuse compartment on one amp, it likely won't fit onto another amp.  Just too much work to make it custom for every amp. 

Add to that the fact that there there is no performance improvement.  I was attempting it solely becasue there are a very large number of audiophiles with zero electrical knowledge and they can't get it through their head that the way SDFB is delivered provides the same, or better, protection.  They think putting the slug in the fuse location is heresy.

Jerry

@tksteingraber I have taken mine apart many times. I know the design inside and out.

@mitch2  I don’t know if you have seen the inside of a SDFB but I added a photo of one on my systems page to view. Thought it might be of interest to folks.  I have trouble posting pics on forum threads…😩

@devinplombier 

I for one am curious to find out how his experiment turns out

I will be happy to share how my installation of the breakers turns out, but I probably wouldn't categorize this as an "experiment" since SMc Audio are currently and successfully using these breakers in the amplifiers they construct and also in the amps that they upgrade.  In fact, I have the same type of breaker (in a lower 1A rating) in my SMc DAC-2, that I received from them last year.  Pics posted on my system page.

The only difference with the install for my amplifiers is that we decided it would be a cleaner and equally beneficial application for me to use the breakers outside of the amplifiers while replacing the fuses with slugs.  Even though I am fairly comfortable self-performing such things, installing the breaker internally is much better accomplished as part of a new amp build, or an upgrade (a process that involves SMc removing all the inside components anyway) than as a customer-installed retrofit.  After discussing what was involved with SMc, I decided not to fiddle around inside of the amp and especially if I can achieve pretty much the same result with an outside installation mounted in a box adjacent to my wall duplex. 

I will share here in advance that, unfortunately, the breakers used are proprietary as SMc Audio spent quite a bit of time figuring out which breakers worked well and sounded best with their equipment.  Therefore, I will not be sharing the manufacturer or model, although it is a 10A magnetic breaker.  I suspect a similar type of breaker is used inside of the SDFB, and it is probably not that much different from breakers that other manufacturers may use currently.  I remember my first experience with a breaker on/off switch was the thermal circuit breaker in the BPT 2.5 power conditioner I formerly owned.

Let's assume for a moment that we know what the "filler" is in an Audiomagic M2 fuse. Some rumor that it is graphene loaded beeswax.

Can anyone here scientifically speculate about the effects thereof? I know how the fuse sounds, but how would it be achieving that sound and why would that sound be different from a bare fuse wire?

@carlsbad2 

We are on the same page. Electrically, a closed relay is definitely equivalent to a straight wire.

So are power cords, but folks still heatedly argue about them.

If we accept that power cords - the essence of a straight wire - can have a sound signature, whether based on brand or copper purity or braiding style, it seems fair to assume that a more complex device inline with a power cord might also introduce its own sound signature.

Re magnetic breakers, I was just following along with @mitch2 's comment:

I am going to receive two of them (10A) that I plan to use for a solution external to the amp chassis, but that will not require an extra power cord like the SDFB.

I for one am curious to find out how his experiment turns out

@devinplombier I agree with most of your thoughts above. I assume by "variable" resistor, you mean that it changes depending on what current rating it is.  

I will explain that the SDFB is basicly a relay with a magnetic current switch to open it (thus, the same as a magnaetic breaker).  So when closed, it is just a pair of contacts in line with the power. So if a good relay, with high power handling and good contacts with essentially zero resistance is chosen, it should be just about like a straight wire.

If you can find a magnetic breaker to put in the line I'd like to see it.  I couldn't find one that would work.

Jerry

I like on many components that I don’t expect to fail, to just raw dog it with no protection and replace the fuse with a slug (some think this is crazy, they are entitled to their opinion).

Reading through this thread leaves me open to the possibility that line fuses, being essentially variable resistors, may have a discernable effect on sound quality. If so, the difference is likely to be confined to fuse vs. no fuse, such that replacing a Bussmann fuse with an "audiophile" fuse is likely to be of no import since the latter is still a variable resistor. So I would have to agree with @carlsbad2 's quote above.

The best way to achieve this, though, is not to install slugs of various metals that can’t possibly make any audible difference, insofar as they are cradled in uber-cheap fuse holders made of common steel. Desoldering and tossing that 10 cent fuse holder and jumpering a length of appropriate gauge wire in its place, thus essentially hardwiring your power cord to your equipment's PCB as @mitch2 suggested, seems the sensible way to go.

As far as the Swiss Digital Fuse Box, it answers the safety question, but it seems highly unlikely that any device sitting inline with your power cord AND needing a 2nd power cord in order to function would not impart its own sound signature onto your system, just like power cords themselves have their own sound signatures.

Can the Swiss Digital Fuse Box be truly neutral sounding, or is swapping it for a fuse a case of robbing Peter to pay Paul, so to speak?

How about magnetic breakers, can they be free of effects on sound quality?

It is of course easy to take the fuse thing to absurd extremes that attract scorn and ridicule, but there is a sound case to be made for eliminating them - in a way that ensures safeguards remain intact of course, or are even improved. Fuses are not that good at doing their jobs anyway, so it is interesting to read about what can be done to improve upon the current situation.

My experience using Sluggo’s is that they are similar to tubes or cables. Each metal has it’s own sound signature. Copper warmer, silver more detailed and revealing, silver/rhodium hollow in between. But the graphene/copper slug was another “Oh My” moment and made the biggest improvement in SQ. Sluggos take many hours to break in and as crazy as this sounds some sound different if you switch their direction after break in. I am somewhat in Carlsbad2 camp where I only use the SDFB for my tube components with rectifiers. All other components with power input fuses I use sluggs without protection. I feel the very low risk of failure and the cost to repair the component is cheaper than buying more SDFB’s. I have never had a power input fuse blow just internal fuses protecting rectifier failures. Some are connecting a single SDFB to a splitter or outlet box and plug in multiple components with the same amp rating to avoid buying a SDFB’s for each component. Not sure of the science to it all but Sluggos do make a noticeable difference in SQ.

When my amps were finished in 2020, SMc Audio had begun doing away with power switches (mine have none) but it wasn’t until a year or two later that they found magnetic breakers that they were comfortable with using to replace fuses.  Apparently they ruled out more than a few manufacturers/models that didn’t sound so good, until they found one they liked.  The magnetic switches they use, like in my SMc DAC-2, serve three roles:

1. Over-current protection for the equipment
2. On/off switch (although less conveniently located on the back)
3. Delay to resist blowing due to in-rush current upon power-up

Their source is proprietary but I am going to receive two of them (10A) that I plan to use for a solution external to the amp chassis, but that will not require an extra power cord like the SDFB.

@pproctor You are correct.  the fuse is indeed the biggest resistor in the entire line.  (there is some voltage drop over the long lines).  so that is why we want to repace or eliminate it.  

The best option is to find something that provides protection but isn't a resistor--thus the SDFB.  

I like on many components that I don't expect to fail, to just raw dog it with no protection and replace the fuse with a slug (some think this is crazy, they are entitled to their opinion). 

and finally, there are expensive boutiques fuses that try to protect your gear with less negative effects, with limited results.  

Jerry

@mitch2 I've trusted copper.  I make my own slugs from high conductivity copper I buy from Mcmaster.  It isn't very expensive.  I haven't bothered with silver or graphene slugs.  I know people trying slugs made of worse conductors like brass or even steel alloys.  these are much worse conductors than copper but much better than a fuse (becasue of the cross sectional area).  So I know there are lots of opinions here but I stick with copper.

Jerry

In the entire power chain, from nuclear reactor through to your component, the piece with the greatest resistance to flow is the fuse, at least among the pieces you have any control over. It would logically follow that assuming input power had any effect (a whole other topic!) it would be the fuse that has the greatest effect.

@carlsbad2 - Have you experimented with whether different fuse replacement slugs make a sonic difference? I ask because I have a solution coming that will allow me to replace the 10A fuses in my monoblocks, so I was looking at options to replace the fuses. I have a hard time believing the $200-300 Graphene Sluggo offered by Underwood should make any difference at all compared to copper. In fact, I have 6.5 mm (~1/4 inch) OD copper tubing with 0.5 wall thickness here and I suspect that would work just fine. The resulting area would be equivalent to greater than 5 awg, which is far larger than the connecting AC wires inside of the amp. Any experience?

Re: blowing audiophile fuses. One of my tube preamps will blow a touchy audiophile fuse if the amp's feeding component (dac in this case) is turned on while turning on on the tube amp. In this situation the dac is first turned off before turning on the preamp. This has ended blown audiophile fuses.

That is certainly possible. eliminate the fuse holder is always a gain.  the fuse holders have to be a metal that has spring so they are often a poor conductor. 

Jerry

@carlsbad2

"So SDFB, designed and built one and did a very nice job."

In our world, $400 for "a very nice job" on something that is actually useful should probably be considered a bargain.

Even if I find the right breaker, finding/buying a suitable box and putting it all together would take hours and even more money. In the end, it still would not have the self-resetting capability of the SDFB. I will probably break down and buy a couple of them for my monoblocks. I would like to consider removing the IEC from one end and hard-wiring a decent power cord pigtail, if that is possible.

Hey, hey, but they can prevent NOISE from LEAKING into your GEAR! ;-)

Dude, there are $1500 Ethernet cables that are apparently "reduce jitter"... Right in the new Music Direct catalog.

@mitch2 I have disassebled and inspected the SDFB.  It is the equivalent of a magnetic breaker.   It sounds like you understand the difference between a magnetic and a thermal breaker.  a thermal breaker has a resistive heater that may be worse than a fuse for sound quality.  

So before the SWFB, I tried very hard to find a suitable magnetic breaker that I could adapt to replace the fuse and I couldn't find one.  So SDFB, designed and built one and did a very nice job. 

Jerry

"What is the science behind audiophile fuses?"

Going back over this entire year and a half old thread, I cannot find where the OP’s original question has been answered.

Since, I do not plan on going sluggo commando, or paying hundreds of dollars for colored fuses, it seems I either live with the normal ceramic fuses I currently have in my equipment, add some Swiss Digital Fuse Boxes, or figure out how to install magnetic breakers.

Assuming the SDFB performs as well as described by @carlsbad2, it doesn’t seem too bad a deal, at least in the audiophile world. One for each monoblock would be $800 for two, which is about par for the course for audiophile tweaks. However, I can’t help but think they may be nothing more than self-resetting magnetic breakers, which is not surprising since many audiophile tweaks seem to be relatively normal stuff dressed up. This magnetic breaker appears similar to what SMc Audio put in my DAC-2. Maybe I will try making my own electrical box with a magnetic breaker and a captive short power cord pigtail.

Jerry’s accounting is sound thinking from an audiophile standpoint, but if you put a slug in your amp and the amp fails massively and somehow starts a fire, you might be out more than the cost of the amp. It is unlikely of course, but it is the reason those fuses are there. 

An accountant can calculate the net present value (cost) of replacing your fuse with a slug.

Lets do an example:

Your amp costs $10,000.

the catastrophic failure rate on your amp is 1/100 years (I think it is really much lower than that, although in lightning areas it may be higher).

Lets say the likelihood that the fuse will save your amp is 50/50. I think it is less.

So the cost per year to put in a slug is $10,000 x 1/100 x .5 = $50.

Now that is statistically what the cost is per year. However, if you happen to have a bad roll of the die, then you’ll have to pay the full $10,000. For many of us that would not be a problem. For many of us that would be a hardship. And even for many of those would could spend $10,000 without any hardship, the worry would not let them sleep.

So some people can replace their fuses with a slug, and some can’t even consider it.

Jerry

PS  Notice I assumed the fuse will save your amp 50% of the time.  The other 50% of the time you amp will fry, even though you have a fuse in it.  so it cost $50/yr to operate your amp with  a fuse and $100/yr with a slug.

@thecarpathian - No worries at all, it is a legitimate question. Aside from code issues, one reason is that a line from the panel is in most cases powering multiple components/devices all of which are probably rated for less than the 20 or 15 amps that trip the breaker, where the magnetic switch/breaker would be rated for the individual piece of equipment.

What I didn’t say is that my amps do not have on/off switches so I actually operate as you suggest, when I want to power down the amps, I walk over two rooms to the panel and throw the breaker or, I can simply unplug them. They probably get powered down about once/month, on average for storms, vacation, etc. They do however have 8 amp (I believe) fuses.

The reasons to consider a magnetic switch/breaker instead of a fuse are reliability, longevity, and supposedly improved sound quality. In the case of my amps, I would need a triple box with spots for two separate magnetic switches, one for each amp, and the duplex that I plug them into. Of course, I would need to split the dedicated 20A line in and then each of the two outlets in the duplex would have to be fed separately from one of the magnetic switches so the amps could individually trip their dedicated switch.

BTW, SMc audio has started using magnetic switches instead of fuses, and they did so on the DAC-2 I received from them last year.

@mitch2 ,

Sorry man, rereading how I wrote that sounds like I’m getting onto you about what you’re considering. That’s in no way the case. It's actually a general question to anyone who has a plausible explanation.

@mapman ,

That’s the most plausible answer I can come with, too.

If something is going to fry inside your amp for whatever reason, how is any safety device placed outside your amp going to prevent that?

I’m totally open minded here, I’d just like someone to explain it to me.

The science is based on $$$s as best I can tell.  

@mitch2 ,

What is an in wall magnetic breaker going to do that the breaker in your panel isn’t?

For that matter, what is one of those Swiss Digital Fuse Boxes doing that the breaker in your panel can’t? Also, what makes it Swiss, does it yodel when it goes off or something??!

Aren’t they all doing the exact same thing, whether they’re attached to the power cord, at the outlet, or in the breaker box?