I wish to comment on the statements about directionality in the article Dave linked to. Consistent with comments that have been made in this thread it states:
There was talk on the web about whether the Black Fuse was directional so I called up Eliott Nommensen, one of the chief operatives in product development at Synergistic Research and asked him about this. He said yes, it’s true but there is no way of knowing which way to is the proper orientation, other than listening, because you can’t really see the circuit inside to figure out which way the fuse holder is wired. He suggested trying both directions when first using the fuse. One way will give you more detail than the other. That’s the way you want to leave it and during the burn-in process the sound will fill in and smooth out. Oh, great. I had already burned them in, so there was a 50/50 chance I had done it right. Late at night, I did the critical listening comparison and sure enough, there is a difference. The correct way has better focus and soundstaging, the other way is more diffuse and the soundstage is vaguer.
First let me say as an experienced designer of advanced electronics (not for audio) I have never had any doubts that a fuse can make a difference in many applications. Although I have expressed some puzzlement in this and other fuse-related threads here about how the benefits of upgrading to a specific fuse could occur with the high degree of consistency that has been reported, among components that are completely different in design, that perform completely different functions, that are used in very different systems, and that are powered by AC having very different voltage and noise characteristics. Which is not to say that I doubt the accuracy of most of the reported perceptions, many of which were provided by members for whose credibility I have particularly great respect.
But I do have a great deal of skepticism regarding claims of directionality in fuses, which IMO is fundamentally irreconcilable with any reasonable understanding of how electronic circuits work. Which is not to say, of course, that an understanding of how electronic circuits work can explain or predict everything about what we hear or don’t hear from our systems. It certainly can’t. But it can often help to provide a perspective on what does or does not have a reasonable possibility of being audibly significant, as illustrated in the last of the comments quoted below. And again, none of this is to say that I doubt the accuracy of most of the reported perceptions, it just means that in cases where those perceptions are accurate I believe that the cause was something else.
And in that regard it would seem I’m in what I would consider to be pretty good company. Among the participants in the various fuse-related threads that have appeared at this forum there have been at least four different experienced designers of well-regarded audio electronics. Following are some of the comments they have posted in these threads.
Ralph Karsten of Atma-Sphere:
… Fuses are inherently incapable of having directionality in any way whatsoever.
… 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…. 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.
Peter Noerbaek of PBN Audio:
How can you be sure that it was the fuse "direction" that made the change in your systems sound, in order to change the fuse you will have to shut down the system then power it back up again then wait for it to return to a fully equalized stage again then make judgement. This powering down / up, the resetting of connectors including the ones on the fuse holder itself will have MUCH larger effect on sound than in which direction the fuse is installed and is probably the real reason that there is some if any difference in sound.
Also in order for the experiment to have any validity at all you would have to be able to recreate the same situation , over and over and over again. i.e. you should be able to hear that if someone had changed the direction of the fuse without your knowledge - I’d state that this would be impossible.
George Stancheff, designer of the Lightspeed Attenuator among other things:
It’s all VOODOO.
Roger Modjeski of Music Reference and RAM Tube Works:
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 never mind, 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.
[Note: 0.038 milliohms is 0.000038 ohms]
IMO, YMMV, FWIW, etc. Regards,
-- Al
