Fuses that matter.

Al,

I really should refrain from posting after 11pm. My attention to detail declines markedly. Yes, I meant 5x20mm.

I'm just curious as to whether you think one should generally be concerned with the specs of after market fuses produced by reputable companies like Synergistic and Hifi Tuning? The Littelfuse for my amp costs a mere $1.67. Surely, we can't be talking about a product that is beyond Hifi and Synergistic's ability to re-produce, assuming there would be any profit in it for them.

Does the data sheet reveal anything to you that would indicate how it is "special" or "out of the ordinary?" I ask because you clearly know more about this technological data than I do.

Regards,

V.

Hi Vance,

I don't doubt that these companies COULD replicate the protection characteristics of the stock fuse. However, different designs of just about any electronic product differ in terms of their design goals and philosophies, and how the tradeoffs that inevitably must be made between many different parameters are prioritized.

As you've seen in the datasheet, even something as simple as a fuse has a great many different specifiable parameters. In addition, earlier in this thread links were provided to papers prepared by HiFiTuning which presented several pages of comparisons between various measurements of various makes of fuses. The data differed widely among the different fuses. (Although I commented that IMO none of the differences appeared likely to be quantitatively significant, and even if some of them were quantitatively significant in some applications, I saw no reason to expect the resulting sonic effects to be consistent among different component designs, and among different AC line voltages).

So given the many parameters that are involved, and the diversity of measured data for different fuses having similar current ratings, it seems to me that while the aftermarket fuse manufacturers COULD replicate the protection characteristics of this particular Littelfuse, I would have my doubts that they DO closely replicate them. But as we said earlier, it will be interesting to see what they provide in response to an inquiry asking for breaking capacity and nominal melting numbers.

Here's another thought, though, that is suggested by the numbers in the Littelfuse datasheet. On the first page, take a look at the numbers in the table of "opening times" (i.e., the amount of time required to blow) that are shown at the lower right. Note in the entries for 275%, 400%, and 1000% that the range of specified opening times for a given fuse and a given overload is huge. For example, for fuses rated between 8 and 20 amps, and overloaded to 400% of their rating, the blow time can be anywhere from 0.15 seconds to 5 seconds. That is a huge possible variation from fuse to fuse. Which suggests the likelihood that many other parameters, for which only a nominal value and not a range of possible values are specified, could also have wide fuse-to-fuse variations.

So it seems to me that a useful experiment may be to simply buy a bunch of fuses that are the same make and model as the stock Littelfuse, and compare sonics between them. Who knows, maybe you'll find significant sonic differences between them, and perhaps one or more of them will provide sonics comparable to what the aftermarket fuses would provide.

If you do that, btw, it might be best to split the order among multiple distributors (e.g., Digikey, Mouser, Newark, etc.), which may increase the likelihood that the fuses you try come from different production runs.

Regards,
-- Al

Al,

That's quite a can of worms you just opened. ;-)

I have sent an email to the owner of Hifi Tuning. I'll post if I get a response.

V.

Almarg, i wonder if any manufacture has ever gone about choosing a fuse value this way. I know with certainty two who went to a different value when the first was blowing too often. I think it is more like civil engineering with a big safety factor. After all why not start low and work your way up?

This might be a good time to remind folks that quite a lift in sound quality can be achieved without buying ANY new fuses at all. What are the odds that the existing stock fuses in any given amp or speaker were originally inserted in the correct orientation? If you guess 50% you're correct. So, the trick is to make all the fuses in the system be the correct orientation. The way to do this is reverse the direction of fuses one at a time, listening each time. Reverse the first fuse direction - If the sound gets more harsh and unnatural sounding put the fuse back in the way it was. If you are uncertain which direction is correct by ear, leave as it is for the time being and proceed to the next fuse. Reverse the direction of the second fuse and evaluate the sound. When all fuses have been evaluated, you should observe the system sounds more natural and less distorted and harsh than before you started to change fuse directions. There still might be some fuses that are not in the correct orientation due to uncertainty during evaluation. Repeating the whole procedure should uncover any fuses that still remain incorrectly oriented.