[Roger A. Modjeski]

I read with some laughter, dismay and sadness the follow up on Stereophile May 22, 2012. page 109 concerning the latest hype of Tuning Fuses. Besides my opinion that these are a horrible waste of good money I want to let readers know that these fuses can damage your equipment.

I repaired a RM-9 MK II where the owner had installed 8 of the $49 tuning fuses in the individual fuse holders of the amplifier. Besides spending close to $400 the fuses they cost him another $400 in repairs and $320 for a new set of output tubes. When fuses cost more than tubes something is rotten in Denmark (actually they are made in Germany.) Not only had the fuses not protected the tubes but they had also blown a cathode resistor that I have yet to see fail in any other RM-9. Upon opening the fuse I found that it was not of a high-breaking construction. In fact the construction was such that a 10 cent RadioShack glass fuse offered more protection. Whoever designed this fuse evidently does not know about breaking ratings or how to achieve them. To my knowledge they publish none of the essential engineering graphs of time VS current. Furthermore, I can see nor can I find anywhere UL, CE or any of the standard safety approvals. Given their construction, I doubt they could get any.

I called the distributor to see if there was any technical data and he referred me to a white paper on the website which is down for maintenance for a week. Let's have a look at that when it's back up.

I know it's difficult to do, but if audiophiles would take the money they are tempted to spend on useless tweaks and start a savings account for that money, in some time they would have enough to buy something like a better pair of speakers, new amplifier or something that would really make a difference in their listening.

Now that I have had my say, here's something you can do if you want to experiment. Since we know these are made of silver wire you can get a enough silver wire for $40 to make hundreds of fuses that sound even better and will protect your equipment. Since these fuses are only good for the AC line lets look at what a line fuse does and what you have to do if it blows. An AC line fuse will protect your solid state and modern tube equipment (Not your 1960's tube amp or any tube amp where there are no tube or B+ fuses) from further damage if a rectifier, main filter cap or any short in the high current portions of the product. This is a good thing. We don't want a shorted rectifier to cause capacitors to explode or transformers to burn up. However if either of these occurs, it's going to have to go the the shop to replace the shorted rectifier which is a very simple matter.

I have more audio equipment and test equipment in daily use than most of you and I assure you, other than nuisance blowing, AC line fuse replacement is a very rare event in my experience. For those who are unfamiliar with the term "nuisance blowing" it is a commonly accepted term for a fuse just wearing out. It is caused by the simple fact that every time a piece of equipment is turned on, the inrush current, which is many times the run current, expands the fuse wire eventually causing it to break. Usually it takes years and when a fuse fails in this manner one simply replaces it and goes on for another similar period. It is more common with fast blow fuses which are not good choices for line fuses for reasons given below.

Fuses are of particular interest to me and every time I replace a fuse I give consideration to what fuse I would have used had I designed the product. Though cautioned "replace fuse with same type and value as original" I often wonder how carefully the "original" fuse was chosen. I have seen a lot of bad fuse choices and have replaced many a fast blow fuse with a much lower current slow blow which often ends the nuisance failures and improves the safety of the unit. I have found many products where the specified fuse would not protect against a shorted filter capacitor or shorted rectifier because the fuse would not blow under those conditions. Instead the power transformer would overheat and fail, then it would blow the fuse. Now there is a lot of stuff to replace instead of the simple diode.

In the original RM-4 I did many tests to determine that the 250 mA slow blow fuse would protect against every possible failure. I shorted a rectifier to see what happened. I shorted a filter cap. I shorted the main supply which never blows a fuse because, unlike many regulated power supplies it is short-circuit protected.

So, how do you make your own silver fuses. Simply wrap the right size silver wire from post to post of the fuse holder and solder.

[Devil Doc]

I read that article last night. I was shocked at what an a audiophile fuse costs. Even if they worked I wouldn't buy them. And let's not forget the brass gong. Hell I'll just mount my Paiste 22 in. China cymbal between my speakers. At least it has silver in it.

Doc

[medium jim]

Anybody who buys tuning fuses needs to be tuned!!!  What a joke and a waste of money...I'm glad that the OP posted his first hand accounts as a guy who repaired the damages caused by the snake oil called tuning fuses.

Jim

[Roger A. Modjeski]

Am I the OP? What does that stand for? I am horrible with abbreviations.

[rpf]

Original Poster.

[Roger A. Modjeski]

That's good to know...

[medium jim]

Roger:

I should have named you by name as opposed to reducing you to an acronym!  Nevertheless, I'm pleased that you started this thread as too many people are falling for the selling hype about these things that when you reduce it down to the facts cannot have any bearing whatsoever on the tone/sound.

Jim

[mark funk]

You know, there is a lot of money out there that people just want to give you. What about the pet rock! Only if I did not have to look in the mirror every day I could be rich  .



                                                                                       

[mtodde]

I tried one in a Modwright SWLP external tube power supply a few years ago and within 30 minutes the fuse blew.  I called The Cable Co and they sent a replacement quickly.  It blew when I turned the preamp on.  At that point I said shame on me and put the stock fuse back in...it didn't blow.  I ate the $30 and considered it a cheap lesson.

[Roger A. Modjeski]

I tried one in a Modwright SWLP external tube power supply a few years ago and within 30 minutes the fuse blew.  I called The Cable Co and they sent a replacement quickly.  It blew when I turned the preamp on.  At that point I said shame on me and put the stock fuse back in...it didn't blow.  I ate the $30 and considered it a cheap lesson.

Thanks for sharing your experience. Was it a slow blow?  The cause might have been hold up time (surge rating).

I called the distributor and there are no curves for hold up/blow time vs current. Furthermore the fuses have no UL/CE/CSA or any safety ratings. Their reply was "high-end equipment doesn't either". However I reminded him that competent engineers rely on the accuracy of fuse ratings to protect their designs and without that we can't recommend or employ their fuses. I use the highest quality parts from  Wickmann which was bought by Littlefuse, a company that understands fuses, publishes curves and has every approval known to man on their fuses.

[Clio09]

This thread is somewhat timely to this one and should be good for a few laughs:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1335381323&&&/Fuses-that-matter-

[medium jim]

I posted the term, Confirmation Bias, in another thread and got blasted, oh well....there is no doubt that tuning fuses are junk and physically cannot alter the sound on bit...if they could, don't you think that those who put their moniker on the pricey audio gear would be using them!

Jim

[JakeJ]

Thank you, Roger Modjeski, for that bit of sanity!

Question, does any specific wire metallurgy make a difference sonically, electrically or otherwise?

And for those members considering purchasing a pet rock, I recommend these: http://www.audiocircle.com/index.php?topic=22961.msg203890#msg203890

They work because they do work! 

[kevin360]

Roger,

Thanks for the excellent post. I consider a fuse without an I2t rating to be a piece of wire - apparently, that's what they are. This may imply that they can improve the sound of gear 'at the limit' (as the current through them approaches the melting point of a proper fuse (because these damn things aren't fuses, they don't get as non-linear as fuses)).

There was a discussion concerning these fuses a short while ago on the Planar Circle. You just satisfied my curiosity about what was inside these damn things*. I thought the company's write-up was funny in that they ask how much sense it makes to put a 10 cent fuse in a high-end piece of gear, but they don't seem to give a second thought to putting a $50 fuse in a 10 cent holder - puhleeze. 

PT Barnum was right.

*We wondered how any fuse avoided the non-linear behavior of being a fuse. Apparently, the answer is simple - just construct a 'fuse' with an element that doesn't melt.

[Roger A. Modjeski]

This thread is somewhat timely to this one and should be good for a few laughs:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1335381323&&&/Fuses-that-matter-

Thanks for the link. It is most amusing and thanks for linking audiogon back to this post.

Reading these posts in most amusing this writer really made me smile.

04-27-12: Kijanki
Naysayers don't realize importance of the fuse and its influence on the sound. Just to test it I removed fuse once from my amplifier and sound was gone. I mean gone completely. Fuses are absolutely necessary for good sound.

04-27-12: Kijanki
I've never tried better fuses but if it's only placebo effect that's OK too, as long as it works for you. Enjoy the improvement but don't do any double blind tests because you might loose all the effect.

04-28-12: Kijanki
Wolf_garcia, Forever? What about house wiring. You have no idea how long and painful it was to pull and reinsert wires in opposite direction. I'm working on power company to do the same but for some reason they are very resistant to this idea (definitely not audiophiles)

Does anyone care that Tuning Fuses have no agency approvals or time/current curves? How do we know if these fuses will protect our equipment? They have already proven to have no protection in DC circuits where myself and many designers are protecting tubes directly. Have a look at the data from Littlefuse, the brand I use. They are approved by 10 significant agencies. I doubt Tuning Fuses could get any of these agency approvals. If indeed they provide inadequate protection then we might as well short out our fuse holders.

http://www.littelfuse.com/data/en/Data_Sheets/Littelfuse_Fuse_215_Series.pdf

In all honesty it bothers me that some guy in Europe who knows nothing about designing fuses is making these and some guy in New Hope PA, who knows even less is distributing them and some respectable merchants are selling them and that magazines are giving credence to their effect rather that pointing out at a minimum that these fuses have unknown ability to do their job of protecting your valuable equipment.

[Roger A. Modjeski]

I just posted the following on Audiogon. Sorry, I just cant leave this alone.


Fuses that matter.
Has anyone considered what portion of the total resistance the fuse contributes to the whole of the circuit in which it is inserted?

From the Tuning Fuse data sheet their 2 amp slow blow 5x20 fuse has a resistance of 24.077 milliohms in one direction and 24.115 in the other direction and 26.257 in the holder. If a butterfly flew by while the measurements were taking place we might see a bigger difference than the 0.038 milliohm difference in direction. Of course it might depend on which direction the butterfly was flying. But nevermind, the direction measurements were made with DC and we are using these fuses in AC circuits. Perhaps if the butterfly flies clockwise vs counterclockwise there will be a difference.

Sorry I just had to put that in to keep up with all the humor that has been presented here.

Back to the numbers: A common fuse of the same rating from Littlefuse has 37 milliohms (note that they don't take the numbers to 5 places being real scientists). So lets look at the total resistance of the circuit. A device that uses a 2 amp fuse will typically have a transformer whose primary resistance is 5 ohms or so and it's wound with around 200 feet of ordinary copper magnet wire of about 24 gauge.

The wiring from your high grade hospital outlet back to Hoover Dam is about 0.5 ohms, which is really quite amazing. It could be as high as 1 ohm. And lets not even think of what that's made of.

So to add it up the tuning fuse has a total of 5.525 ohms in the primary circuit and the Littlefuse has 5.537 for a difference of 0.012 ohms or one part in 458. In decibles that difference is 53 dB down. Now a power supply takes in 120 volts and when by the time it gets rectified and filtered the hum at the main filter is about a volt so now we have reduced the AC to 1 part in 120 thats another 41 db.

Your unit likely has a 50 cent three terminal regulator that reduces the hum by another 60 db or the amplifier itself does that. So now we are down 53+41+60 dB for a grand total of 154 dB. I am really impressed with listeners who can hear a difference that's 154 dB down.

Shall we do the numbers on the microphonics next?
by Rogermod

[Clio09]

Nice job Roger. I wish you would post on Audiogon more often but I realize how busy you are and I myself would prefer you spent your time on new designs and educating us here.

[Scott Novak]

Does anyone care that Tuning Fuses have no agency approvals or time/current curves? How do we know if these fuses will protect our equipment?

After having spent 6 years performing safety testing on switching power supplies I would be very concerned about using any protective device, fuse or circuit breaker, that did not have safety agency approvals.

In order to obtain approval by a safety agency, such as UL, CSA, TUV, etc., you must prove that your product will not catch fire or present an electrocution hazard if any component in your equipment fails.  This is all that most manufacturers care about.  But manufacturers are also often cheap and greedy and often avoid installing fuses that cost them extra money and could possibly cause nuisance tripping.  They don't care if every component inside the equipment fails, as long as the equipment does not catch fire or present an electrocution hazard.  Quite often the equipment is dependent upon the branch circuit breaker in the building tripping to protect the equipment from catching fire.  Most electronic equipment would benefit from the addition of a few extra well placed fuses.

The equipment may have also been designed dependent upon a safety agency approved fuse opening to protect the equipment from catching fire or presenting an electrocution hazard.  If you substitute an improper fuse you could be jeopardizing your own safety.  As an electronic technician I would never considering installing a non-safety agency approved fuse in customers equipment as I would incur a serious liability if some non-approved fuse did not work properly and the equipment set the house on fire or electrocuted someone.  I also prefer to use a well known brand of fuse such as Littlefuse of Bussman.  I just don't trust the generic brands.

I won't dismiss the possibility that a fuse can affect the sound.  However, the degree to which a fuse could affect the sound is likely dependent upon where the fuse is located.  An output fuse or a speaker fuse would likely have the most effect on the sound as the signal travels directly through the fuse with a substantial current.  However, the contact pressure of the fuseholder on the fuse is likely to have a more significant effect upon resistance and sound than the fuse itself.

A fuse inside a speaker cabinet is one location where even the elimination of a fuse will not likely cause a safety hazard.  It may just be very expensive if a fuse does not blow to protect your speakers.  However, an output fuse on an amplifier might be necessary to keep the amplifier safe in the event of a component failure.

I have serious doubts that a fuse on the line side of the amplifier will have any noticeable effect on the sound, unless the fuse is seriously defective.  Roger has already outlined how isolated the line side is from the power supply output.

The talk about the directionality of the fuse also seems ridiculous. If there is more resistance in one direction than another that indicates the likelihood of a diode effect.  Now consider that your amplifiers are not capable of using the AC power until they rectify it with diodes in series with the transformer secondary winding.  The diodic effect of the rectifiers is many orders of magnitude higher than any piece of wire inside a fuse and the diodic effect of the rectifiers would swamp out the diodic effect of the tiny bit of wire used inside a fuse.  If there is any measurable diodic effect it is more likely to be caused by the junctions and intermetallic interfaces between the wire inside the fuse and the end caps.  It's also very possible that some of these effects are actually thermoelectric effects of dissimilar metals contacting each other.

Fuses also have a DC and an AC voltage rating.  When the fuse element opens an arc is formed and current continues to flow, just like an arc welder.  When the fuse in installed in an AC line, as soon as the voltage crosses the zero point current ceases to flow and the arc usually stops and no more current can flow and the circuit is protected.

However, it is far more difficult to make a fuse work properly with DC current, because the DC is not switched off to the fuse as it effectively happens 120 times a second for 60HZ AC lines.  Instead, the arc that was formed when the fuse was opened can often continue until something physically gets in the way of the arc, such as sand inside a fuse body.

So until Tuning fuses proves to the world that their product meets the various safety agency approvals, and they publish their AC and DC voltage ratings there is no way that I'll use them.

Scott Novak

[JakeJ]

I second Clio09's post.  One cannot refute true science and engineering.  We, as consumers, must educate ourselves or we finance a world of BS.

[Clio09]

Roger, I don't think your post got past the Audiogon censors. At least I haven't seen it yet. Maybe I will try to point that thread back over here one more time or copy your post here and see if I can get it through.