What is the science behind audiophile fuses?

Fuses have to heat up and blow to protect the downstream equipment.  So they have to have a significant resistance (to heat up) and as current goes up, they heat up, resistance goes up (a property of all metals) and they heat more and blow.  This isn't a problem for electric motors or household equipment.  but a high end amplifier can have dynamic changes in power requirements over a very short time which can be limited by the fuse.  If this happens to your air conditioner, it will still cool.  If it happens to your amp, it will still make music, it just won't be as dynamic. Bass will suffer as well.  

An audiophile fuse supposedly has less resistance and limits current less.  I have never bought one and don't plan to.

I replace fuses with slugs.  an overcurrent situation in an amp is very unlikely and when it does happen it is usually caused by user error.  There is a very audible difference in most amps replacing the mains fuse.  This is especially true of tube amps.   Also if your amp has fuses on the rectifiers they should be replaced.  

No your amp won't burst into glorious flames but if you can't get this image out of your head, keep your fuses.

I have tested the Swiss Digital Fuse Box that replaces the fuse with a magnetic current sensor and a relay, thus there are no heated components in the power circuit.  My opinion of this piece was that it was better than any fuse but not quite as good as a slug.  It is also cheaper than an audiophile fuse.

Jerry

@tksteingraber Slugs are solid copper jumpers that replace the fuses.  No protection.  --Jerry

@tksteingraber realize that the fuse replacement is just a short piece of conductor adjacent to the power cable.  I don't think you'll ever hear a significant effect fro different coppers on such a short piece of conductor, just so it is heavy (not thinwalled tube).  Now often the fuse holder is not great--it can't be soft copper or it will relax and not clamp the fuse.  Often they are .....clears throat....whispers....steel.  so a good fuse holder would be where to focus your interest. 

That said, I'm as audiophile geek as anybody so I buy high conductivity copper 5mm bar from McMaster car, cut it into fuse lengths on my lathe, and polish with scotchbrite.  I'll be glad to send you one if you want one.

Jerry

@thyname thanks for the shout out as the original "we don't need no stinking fuses" guy.

I have tested the Swiss Digital Fuse Box and recommend it over any fuse.

My impression was that it wasn't as good as the "large gauge piece of metal" (high conductivity copper) but not a lot of difference.  If you feel you need/want electrical protection, I recommend the SDFB.

I think some people are confused about the configuration of the SDFB.  It provides better protection than a fuse.  Generally a magnetic current monitoring circuit will trip much faster than a slow blo fuse.

Of course we've all had experience where a compoent failed and the fuse didn't protect it.  that's just the nature of electronics  the fuse protects against upstream disturbances more than downstream failures.

Jerry