We Need A Separate Forum for Fuses

geoffkait - last time I tested a fuse for resistance, I think the value on my meter was 0.000 ohms.

Seriously though, if there was a resistance in your fuse, there would be a voltage drop accross it, which would adversly affect your equipment and comprimise it’s design.

Fuses are designed to only dissipate heat (and therefore present a resistance) very close to the point of failure. If your fuse is presenting a resistance it must be dissipating heat to some extent, which will lower the voltage accross it, which will be measurable with a meter (however good). If this was the case, then I would suggest using a slightly higher rate fuse e.g. swapping a 2.5amp for a 3amp

Either way, any fuse operating that close to it’s limit would blow with the least provocation; i.e. powering up the amplifier would blow it.

Last weekend, a guy who had a pair of Frieds came to my house for help getting them to work. One of his loudspeakers had the fuse holder break, and he found himself stuck.

Most loudspeakers Bud produced came with "tweeter protection", consisting of either a fuse or light bulb, as in his own words, he hated doing warranty work at his cost. I’ve learned over the years the conventional wisdom of protecting tweeters via a fuse doesn’t work the way folks think. They still fry over time. Except in moments of huge power coming into the loudspeaker, the fuse proves worthless.

Anyway, I simply bypassed the fuse, and made the connection on the crossover to allow his speaker to come back to life. We tested them out by playing them, and even at his advanced age, he instantly noticed this speaker sounding very different (better!) than the other. I soon bypassed the fuse on the other speaker to balance them out. He couldn’t believe how much the fuse degraded the sound

trelja - the fuses in a speaker are going to be operating with a valiable voltage depending on the volume, so they will, as I suggested in my post above, be skirting very close to their blow point at times and will therefore be prone to dissipating some heat, so I would expect some voltage drop and a notable difference in the sound - the increased heat and resistance will throttle the current available to the speaker and this is likely what you can hear.

However, the fuse in a power supply or on the supply rail of an amplifier is not exposed to such variation - it’s handling a DC supply, rather than an AC signal. Let's leave fuses in your AC 120v / 220v supply aside for now.

There is a big difference between the behavior of supply current and signal current and fuses will behave differently with each.

I thought your tweeter story was fascinating, but I would doubt whether the expensive fuse would sound better than the regular fuse - however I can see why no fuse would sound the best!