thank you!
I no longer have a reference to the article but one person did a series of noise level measurements on fuses in terms of orienting them first one way and then the other. There was a repeatable difference with one orientation yielding a lower result. I have no idea why thatâd be the case. I do know from when I used HiFi Tuning fuses (Silver, Gold and Supreme) that I preferred one orientation over the other. The difference being one way sounded more âopenâ than the other for lack of a better way of putting it.
if you find the article again please post it.
Many have reported both better sound with aftermarket fuss, together with differences in sound with fuse orientation. It is a common enough report to ask why rather than to dismiss the finding.
These fuses act as a filter/diode of some sort.
Fascinating stuff.
I found the reference but the online link is no longer active. I have it saved on my hard drive and could e-mail it to you if you like.
This is an excerpt from a 2010 white paper from HiFi Tuning. The original may still be available on their web site.
"There is a measurable difference in directivity of fuses. Mostly that will be due to the way the melting wire is manufactured. The difference is in the range of 5 % . That is in the range of variations due to the factoring process, but the difference is measurable with all types of fuses.
The resistance of the fuse itself is dependent on the length and thickness of the melting
wire. At pure DC- resistance measurements, of the commercial available fuses, the solder
type with leads gives the best results. Worst results gives the fuse with a glass tube and
spiral shaped melting wire.
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5% is not much of a difference, interesting this can be heard.
I know, it doesnât seem like all that much to me either. But, it would appear to be noticeable.
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I have compared both directions on stock PS fuses and three different cheap fuses. In each case, one direction clearly sounded more open in the treble and midrange.
Thank you for better putting what I was trying to say. Thereâs a review of the HI-Fi Tuning Gold fuses somewhere by Myles Astor where if I remember right he heard the difference in direction in the midrange. Itâs been quite some time and I may have that wrong.
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No problem, I edited my post to clarify what I have heard. It is more open in the treble and the midrange, maybe more in the upper midrange.
I found this:
In addition, HiFi-Tuning fuses are directional (this is also measureable). Now the effect of switching the direction of the fuses using Roy Haynesâ Out of the Afternoon (Analogue Productions/Impulse AS-23, 45 rpm) is subtle but nonetheless incorrectly oriented, the HiFi-Tuning fuses produce a sound that is a little pinched, boring, rolled off and more veiled.
From here: hifi tuning
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Youâre detective work is appreciated, thanks. 
His review of the CJ Premier 140 amp was instrumental in my purchasing it back in the day. His observations were borne out in my experience and I donât think it was a simple case of listener bias/expectation. He was on the money.
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Yes, my girlfriend was present a few times that I compared fuse direction and even she noticed what I heard (without me saying anything more than âdid you hear a difference?â)
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Uninterested/disinterested witnesses can be instrumental in cutting through expectation bias.
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Absolutely, Elk. She can get annoyed if I ask her too often, so I ask strategically.
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FUSE TIP: Just like cleaning your connections, cleaning your fuse tips (end caps) is worth doing.
Thanks, what do you recommend using to clean them?
I like 91% isopropyl. It works very well and leaves nothing behind. Lint free cloth is preferred.
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Iâve experimented with silver conductive paste on fuse connections to good effect. The interface between the fuse cap and the blades that contact it arenât all that great.
Be careful, a little goes a long way. Think of it as thick liquid wire. This qty will last many years.
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ainât that the truth 
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