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?

Thank you, Roger, for bringing the expertise of a distinguished designer to this issue. As I said in my post dated 4-29-12, the explanations that tend to be offered for the supposed benefits of expensive fuses seem plausible until they are looked at quantitatively.

Best regards,
-- Al

"Thank you, Roger, for bringing the expertise of a distinguished designer to this issue."

Amen.

My best opinion is that a fuse that effects the sound in a significant manner is defective and should be replaced by one that is not.

Roger makes a compelling case. When I hear things like that, it erodes my confidence in my (already tentative) belief that fuses have audible effects. Having said that, I conducted a second experiment (I use that term loosely) that corroborated (I use that term loosely as well) my initial impression that fuses do in fact have audible effects.

In my first experiment about a week ago, I A/B'd the stock fuse in my amp with a Hifi Tuning fuse. I swapped back and forth about 15 or 20 times. Each time, I heard a difference (or to put it less controversially, I BELIEVE I heard a difference). What surprised me almost as much was the fact that I preferred the sound of the amp with the stock fuse (15¢) rather than the fancy fuse ($50).

The day before yesterday I conducted a similar experiment with my preamp. Again, I swapped fuses maybe 15 or 20 times. Again, I heard (or believe I heard) a difference. Again, I preferred the sound of the stock fuse.

In both the amp and the preamp, the Hifi Tuning fuses had a strange phasiness, lack of pitch definition in the bass, and imprecise imaging. None of that was audible with the stock fuses.

Possible interpretations of the data...

1. Fuses have audible effects.
2. I am crazy.
3. A butterfly is trapped somewhere in the house.
4. All of the above.

Which of these is true remains unclear. So I've done the only thing a sane, rational, and sensible person could do.

I've ordered a Furutech fuse.

Bryon

Bryon, Roger talks about any detectable change in sound while we discuss here if "major difference in my sound" that Tbg experienced can be repeated and benefit others.