We Need A Separate Forum for Fuses

Geoffkait 3-18-2018
But when we talk about fuse directionality we’re referring to the idea that the fuse sounds better when the fuse is inserted in one direction rather than the other. A fuse in an AC circuit is directional because what you hear in terms of sound depends only on the signal during the alternating cycle when it is traveling toward the speakers from the amp or to the amp from the wall, whatever. You don’t care what the signal sounds like when it’s traveling back toward the wall outlet. That’s why fuses in AC circuits are directional.

Geoff, you've stated this explanation a number of times in various threads. However with all due respect **even if** fuses are somehow inherently directional in AC circuits to an audibly significant degree I would be surprised if there were a single competent and experienced electronics designer in the known universe who would agree with this explanation.

In the case of a mains fuse, when AC current is moving toward the component in the "hot" conductor it is moving away from the component in the "neutral" conductor. And vice versa. So it is moving both toward and away from the component at all times. And a mains fuse is in series with the current in the neutral conductor as well as being in series with the current in the hot conductor, via the primary winding of the power transformer.

And simultaneously, as I'm sure you will agree, energy is being transferred unidirectionally, toward the component at all times, in the form of an electromagnetic wave comprised of photons that is distinct from although intimately related to the AC current.

Similar considerations apply in the case of a speaker fuse, the relevant difference simply involving terminology (the two conductors usually being referred to as positive and negative rather than as hot and neutral).

I will have no further comment on this matter.

Regards,
-- Al
 

Hi Elizabeth,

While others here disagree, IMO the most plausible explanation that has been offered regarding fuse directionality was provided in this thread by Atmasphere (Ralph). As you’ll see it recognizes the legitimacy of the many observations of fuse directionality that have been reported, but at the same time does not mean that a fuse is **inherently** directional. And note that he has performed actual measurements which support his explanation. Some excerpts from his posts in that thread:

Atmasphere 5-23-2016
If y’all are interested, I think I’ve sorted out what this reversal phenomena is all about.

It has to do with the fact that the connections on fuse holders are not perfect. The act of reversing the fuse sometimes gets you a better connection. However, directionality really isn’t the issue. Similar to a power switch, the contact area of the fuse holder that is actually doing the work is a fraction of the total contact area. As a result, if you simply rotate the fuse in its holder, you will find that there is a best position where more of the fuse holder contact area is touching the fuse contacts. When the fuse was reversed, on occasion you got better contact or worse contact, which appears initially to be a directional issue, but that is really an illusion.

Interestingly, this effect is measurable as a voltage drop across the fuse holder. As you might expect, the less voltage drop the better. So it is possible to adjust (rotate) the fuse in the holder for minimum voltage drop and thus the best performance. A side benefit is the fuse will last a little longer as the operating temperature is reduced.

Atmasphere 5-26-2016
... I joined this thread recently with some results on testing. Those results are that the directionality appears out of coincidence and that actually greater improvement can be had by rotating the fuse in the holder for best contact. The improvement is measurable and audible; descriptions others have made on this thread of what happens when you get the direction right accurately describe what happens when the contact area is maximized.

Occam’s Razor has something to say here! Given that a fuse has to be used in AC circuits and given that people report differences by reversing the fuse, and also understanding how fuses are inherently incapable of having directionality in any way whatsoever, the explanation that they somehow have an effect by reversing them in the holder is a fairly complex explanation: some sort of unknowable, unmeasurable quality of the fuse itself.

A simpler explanation is that the reversal is improving the contact area because fuse and holder are not dimensionally perfect and the fuse might sit better in the holder in one direction. By rotating the fuse in the holder without reversing it gets the same effect only more profoundly.

While Ralph’s explanation may strike some as being at least somewhat implausible, even though he has performed measurements supporting it, to me and I believe to most others having electronic design backgrounds it is far less implausible than the notion that a fuse would be intrinsically directional.

Also, as far as I am aware exactly one member here besides Ralph has reported inserting and re-inserting a fuse with differing rotational orientations and comparing sonics, a member by the name of SGordon1. Like Ralph he found that significant sonic differences resulted, and encouraged others to try this.

Regarding your thoughtful hypothesis about magnetic fields, the magnetic field surrounding a fuse would have a magnitude and be in a direction corresponding to the current flowing through the fuse, which I would not expect to differ as a function of which way the fuse is inserted.  Aside, that is, from the small effects on magnitude of the phenomenon Ralph has described.

Best regards,
-- Al

One of the goals of a good designer will be to minimize the sensitivity of the performance of his or her design to extraneous factors, such as the vagaries of incoming power, expectable differences in the characteristics of other system components that may be used in conjunction with the design, and, yes, fuses. However, based on a very substantial body of empirical and anecdotal evidence it seems clear that as a practical matter that goal generally falls well short of being fully realized.

On the other hand, though, IMO it is also true that the correlation between sensitivity to extraneous hardware-related factors and the sonic quality and musical resolution of a design also falls well short of being perfect. To cite just one obvious example to illustrate that point, among countless other examples that could be cited:

Everything else being equal, a speaker having low impedance, and/or an impedance which varies widely over the frequency range, will be more resolving of differences between amplifiers and speaker cables than a speaker having high impedance and/or an impedance which doesn’t vary greatly over the frequency range. Would one conclude from that fact that the high impedance speaker is necessarily inferior in terms of sonic quality and resolution of musical detail? Or going even further that the high impedance speaker is "junk" and "horrid design"?

So just as maximizing the sonic quality and musical resolution of a design may have a tendency to work in the direction of increasing sensitivity to extraneous hardware-related factors, intelligent circuit design may have a tendency to work in the opposite direction. And generally speaking, IMO, the net result of those competing tendencies will be a correlation between sonic quality and resolution of musical detail on the one hand, and resolution of hardware differences on the other hand, that while being significantly greater than zero is also significantly less than perfect. So I would have to respectfully but emphatically disagree with Doug’s blanket characterization of insensitivity to fuse differences as signifying "junk" and "horrid design." And I believe that most experienced electronics designers would agree with me.

Regards,
-- Al