2. amps-preamps
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New Fuse Thread . . .

So the talk about the sonic effects of fuses got way out of hand, and I would like to know some details from those who have actually tried the boutique audio fuses. So if you have, please let us know any of the following:

1. What value (ampere rating) were you using, and was it fast or slow-blow (time delay)? Time-delay fuses usually have a letter 'T' in their rating, like "T2.5A" is a 2.5 ampere, slow-blow fuse.

2. Does anybody have a reasonably decent ohmmeter, and could you measure the difference in resistance between the boutique fuse and the standard one? If you measure, be sure to subtract the resistance of your test leads. Of course, if somebody has an impedance analyzer, I'd love to see that data . . .

3. What position is this used in? That is, on the AC line, or after the transformer, after the rectifier, etc.?

4. Has anybody had occasional fuse-blowing with the stock fuse, and replaced it with a boutique fuse, and had the boutique fuse blow? Did the failure patterns seem similar to both types?

5. Has anybody made any performance measurements on their equipment with various types of fuses?

So I'm hypothesizing about some ways in which fuses could affect circuit performance, and there are two things I can think of. First, if silver wire is used, then since silver has a lower melting point than copper, the fuse resistance *could* possibly be lower for a given rating. Also, many slow-blow fuses seem to have a resistive element wound around a central core, so it's possible that these could be inductive as well. So what could that mean in a circuit?

First, for a slow-blow line-fuse application, where there is an AC input filter, adding/changing resistance/reactance in the AC line could affect the Q of the input filter, and if this unit was RF suceptible or had a switch-mode power supply, the fuse could therefore affect RF emisions or suceptibility.

Second, many power amplifiers have no snubber capacitors on their rectifiers, and also use fuses for the power-transformer secondary. It's possible here that changing the reactive/resistive characteristics of the fuse could slightly change the switching speed of the rectifier diodes, and affect the diodes' RF emissions.

Third, some power amplifiers use fuses on the DC rails, after the filter capacitors. In this case, it's easy to see how fuse resistance could influence the amplifier performance.

Fourth, if a fuse was placed between a low-voltage linear regulator (like the ubiquitous 78XX or LM317) and its local input filter capacitor, the characteristics of the fuse could affect the regulator's stability, and cause it to oscillate.

And finally, there's the UL rating issue . . . it's important to have confidence that a fuse will blow when its supposed to, and without any certifications, who's to say? At $40 a pop [sic], testing their tolerance and production consistency is a very expensive proposition indeed.

Now I'm not claiming that fuses make a difference, or don't make a difference, I honestly haven't tried, and I'm too cheap to conduct an exhaustive study into the matter. But if anybody has some good data (even if incomplete) on their experiments, please share it.
kirkus
phaelon
1,038 posts
 

"If engineers are so "all knowing," why don't they employ point to point wiring, black gate caps, Teflon caps in the signal path, OFC copper RCA and XLR jacks, OFC speaker lugs, high quality AC cords, NOS tubes and so on?"

Engineers laugh at "overbuild". Good engineering is all about achieving a goal using a minimum of materials and expense. This is what they go to school for. So, who sets the goal? Now a days, it's usually the marketing guys, and they live by the credo that perception can sell for just as much as reality and costs less to manufacture. One can go on and on with this line of thinking but it's pretty obvious where it ends up...It ends up with all those upgrades Albert noted above. If the passionate audiophile is going to squeeze out the last bit of music from his components, he will most likely have to do it himself.
tbg
5,263 posts
 
Phaelon, I think you paint with too broad a brush. Some small manufacturers, typically not engineers, do use quality parts and state-of-the-art circuits. Nevertheless, what you say is true of what engineers have become in the US. MBAs and the success of their bottom line, or immediate bottom line have lead to this, but engineering schools have also changed from when I was in them.
rodman99999
5,977 posts
 
Mr K- I started with the AC line fuses in my main amps, as I felt that would impact my system the most. You've obviously made the same educated choice. I'm changing the remaining fuses in a sequence, to better quantify what each change yields(rails=large). I've yet to dig the fuse out of my BAT VK-D5, as it's hidden inside the unit's IEC connector/power switch enclosure(and I'm basically pretty lazy).
phaelon
1,038 posts
 
Point taken Tbg. I wasn't really talking about small, super high end manufactures like Lamm Industries or Shindo Labs... They operate in quite a different reality than an engineer for Sony.
warnerwh
539 posts
 
"If engineers are so "all knowing," why don't they employ point to point wiring, black gate caps, Teflon caps in the signal path, OFC copper RCA and XLR jacks, OFC speaker lugs, high quality AC cords, NOS tubes and so on?"

Maybe I'm wrong but I'd think manufacturers making amps for more than say 5k would give you better fuses if it helped the sound of their product. As we all know there's very much competition for our money out there. This is my best guess.

If I manufactured a power amp in today's market adding another 100 or 200 to the actual cost in the 5k and up class would seem very worthwhile because of the the diminishing returns thing.

Bottom line is though that it's your money. Room treatment and or equalization can make a huge improvement. I bring this up because I notice many people saying they can hear a difference between fuses have no room treatment. Once it's treated then you can become a much better judge of your system.

Without the treatment there's no doubt your system isn't operating at it's potential or anywhere near it. Too many room measurements prove this to be argued.
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