Fuses that matter.

04-29-12: Kijanki
If these fuses make "major difference in sound" as Tbg stated then why manufacturer's don't install them in gear they sell...

Hi Kijanki - That's a fair question. I suspect that if fuses did indeed make a major difference, and a manufacturer was aware of it, he MIGHT be inclined to include them in his products.

On the other hand, there are very well respected manufacturers who do NOT include accessories that many audiophiles consider essential to good sound. Most amplifiers, even quite expensive ones, come with generic power cords. My Pass amp came with the same power cord as my microwave. If you believe power cords have an effect on sound quality, then why don't manufacturers include better ones?

Power cords are just one example. I am also aware of a $12K preamp from a very well known manufacturer that has a $55 off-the-shelf power supply. Are we to believe that the manufacturer thinks that a preamp's power supply is unimportant to its sound quality?

In other words, I think that "Manufacturers don't use it, therefore it doesn't affect sound quality" is not a valid inference.

Having said that, I will repeat that I am not convinced that fuses affect sound quality, in spite of a personal experience in which they seemed to. I am open to both sides of the argument. That is why, in my last post, I asked folks to weigh in on the plausibility of the technical explanations offered by manufacturers of fancy fuses. I know you have considerable technical expertise. Do any of the items on that list strike you as plausible?

Bryon

Hi Bryon,

Sounds like you've done a good job of unearthing the kinds of explanations I'd expect to see offered for the supposed benefits of upgraded fuses. I suspect, however, that few if any of the offerings provide a quantitative perspective on the factors you listed.

Re item 3, I have no idea why reducing microphonics in an AC line fuse, if indeed there are any microphonic effects to be reduced, would have any effect on sonics.

All of the other items would have the effect of reducing voltage drops across the fuse or its contacts with the holder, and thereby increasing the voltage provided to the component. In the case of Class AB and Class D amplifiers, that draw widely fluctuating amounts of current, fluctuation of the voltage provided to the component would also be reduced.

That sounds good until we look at it quantitatively. Here and here are data sheets for garden-variety fuses whose characteristics I believe typify the kinds of fuses that would be used in audio components.

It can be seen that the higher amperage fuses, that would be used in power amplifiers, have voltage drops at maximum rated current in the rough ballpark of 0.1 volts, or slightly more in some cases. That drop would be somewhat less at the derated current levels they are presumably used at. For 1 or 2 amp fuses, such as might be used in line-level components, the voltage drops are generally a significant fraction of 1 volt at maximum rated current, and slightly more than 1 volt in one case.

In the case of Class AB and Class D amplifiers, fluctuations in the voltage seen by the component that would result from fluctuations in the amount of current being drawn through the fuse would be some fraction of that 0.1 volts.

Even if the upgraded fuses reduced those voltage drops and fluctuations to zero (which they won't, of course), would such small differences have any audible significance? I suspect that with some components in some systems at some line voltages there might be a marginally perceptible difference. However even if there were a difference, I don't see any reason to expect that it would be consistently in the direction of being better. Especially given that at many locations these days the AC voltage at the wall outlet is higher than the 120V or thereabouts that the components are presumably voiced at.

Best,
-- Al

A characteristically thoughtful and well informed answer. Thanks, Al. You have raised the level of my skepticism about what I MIGHT have heard when I installed the fuses.

I think I will A/B the ordinary and the fancy fuse and see if I can reproduce the effect. I may even experiment with direction. :-0

Bryon

I just think that if there is really a "major difference in sound" manufacturers would upgrade their fuses. Power cords either don't cause "major" difference" or manufacturer assumes you replace them to your liking. Unfortunately fuse in my Rowland 102 is inside protected by 5 years of warranty that is void upon opening of the unit. Why then Rowland decided to use standard fuses? Manufacturer's use other expensive components like Teflon caps - why wouldn't they change component that causes "major sound difference"?

Take into consideration that thermal energy to melt the fuse is described by I^2*t factor. With the same time and same current resistance of the fuse has to be pretty much the same to cause the same amount of heat, unless melting temperature is way lower - not likely with the silver in comparison to low melting point of special alloys used in fuse construction.

Don't get me wrong - I've never tried Hi-Fi fuses, but before I pay $100 per piece I'd like to understand why manufacturers don't use them and how they were able to reduce voltage drop without use of special alloys.

After thinking about this for a while I now believe in directionality.

Facing your speakers and having your back to them, should produce a noticeable audible difference.

Even my pet dog Tommy heard the changes in a series of deaf, dumb, and blind tests.

Thanks Al and Bryon