What is the science behind audiophile fuses?

Not to be intimidated by costly errors, I pressed on with my inquiry into fuses. I made two copper (99.9% pure) slugs, 5x20mm for my mono bloc amps. The engineer in me, being all too well acquainted with Murphy’s Law, was a bit reticent but I pushed on. With the two copper slugs installed in place of the slow blo fuses I listened to several songs. I detected no difference in sound. I put the fuses back and listened again and everything still sounds the same to me. I have two new slo blow HiFi tuning fuses arriving tomorrow but now I’m not sure it will be worth the trouble to swap out the factory fuses.

Now the fuse swap in my DAC made a noticeable difference in the sound- for the better. But in the case with my amps, I’m not expecting to hear a difference since the copper slugs had no impact on the sound. We will see.

So I ground the cap off of one end of my blown hifi fuse and peaked inside. I see a ceramic tube with the two metal end caps. Inside the ceramic tube is a piece of white shrink tubing that fits snugly within the ceramic tube. Inside that shrink tubing are the remains of a filament. It looks like silver wire and has a small shiny ball on the end. I’m sure that’s due to the current draw melting the wire when I powered up my amp. I don’t see any foo foo dust- unless it vanished when I ground the end off.

Anyone willing to sacrifice one of their $400 fuses to peak inside?

So, anti-vibration damping? 2c for $49? 

Inside the ceramic tube is a piece of white shrink tubing that fits snugly within the ceramic tube

I'm guessing the shrink tubing is it.  And even that is necked down just at one end.

"And even that is necked down just at one end."

Maybe from the heat of the solder used to connect that end of the wire to the end cap?  The other end was probably connected prior to installing the heat shrink tubing.

I’m starting to think that the function of these fuses isn’t about conductance. It’s about mechanical dampening. I know someone else brought that up before. It has a silver filament and that’s it for electrical properties apparently. The ceramic tube and then the rubber tube inside that isolate and dampen the filament.

From that standpoint you are getting what you pay for. These are likely hand made and painstakingly assembled. Now, the real question is do they work? In the end you are paying for a product to provide a function. In the case of my DAC the hifi fuse helps. In the case of my amps, that is still to be determined. What I do know now is that the current factory fuse in my amp is not an electrical bottleneck or a restriction for power or sound. The copper slugs proved that- from a hearing standpoint. So will a damped and isolated fuse sound different in my amps? To be determined...