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Hi-Fi Fuses - SNAKE OIL? - or something in it?

There's a lot of chatter about the benefits of those high prices gold plated fuses with silver conductor etc. etc. all over the web and the consensus ranges from FANTASTIC!!! to much more subtle observations.

It makes sense to me, epseically in light of spending lots of $$$ on good power cables, that having a skinny piece of aluminum conductor in a glass tube (i.e. a cheap fuse), in the power loop would be detrimental to the performance of the components.

I decided to revamp my DIY power supply I'd built for the Cambridge Audio 640p phono stage and DACmagic in order to test this out - and since it's a DIY project there is no UL Certification to void.

First, I bypassed the fuse link completely to confirm there would be an improvement and give me the best benchmark to compare against - YEP - BIG DIFFERENCE - much more this, that and the other :-)

So then I started looking for hi-fi fuses - WOW!!! - talk about pricey.

Two fuses for the power supply was going to cost $120+ AND I thought I'd probably have to buy a better quality fuse block to make the most of those fuses.

Then a moment of enlightenment - most power supplies and conditioners are protected by pushbutton breakers and not fuses.

I found breakers of the required current rating and installed them into the power supply. I imediately noticed that there was no deteriation in fidelity when compared to the same unit with the fuse link bypassed - GREAT!.

On reflection, the fuses I had in place were rated at 3 amps - so they use a pretty thin fuse wire in them. If I had used a fuse of a higher rating, i.e. it uses a thicker conductor, then I believe that there would be less of a difference between the fused and bypassed implementations

SO - do the expensive fuses work?

Well the empirical evidence out there would suggest they do
- I do know the cheap fuses are not good!

I know bypassing them does improve the sound - a lot in my case
- BUT THAT'S NOT SAFE FOR ONGOING USE

I know breakers work as good as bypassing the fuse
- BUT MESSING WITH A POWER SUPPLY VOIDS UL CERTIFICATION - NOT GOOD!
- FYI a couple of licensed technicians I know WILL NOT change the design of a power supply at all.

I believe the amount of benefit is related to the fuse rating
- but don't go replacing 3 amp fuses with a 20 amp fuse - that's not safe either.

Whilst looking for fuses I discovered AMR Gold fuses priced at $20/fuse.

Now that's definately more affordable than most others at 3-4 times their price.

One supplier I know of in the US is Avatar Aacoustics

If you have had experience with quality fuses please share - especially if they are "modestly priced" i.e. $20-$30 per fuse. And please provide a source :-)

Also, can anypne confirm that Slow blow fuses are better than regular?

And Remember - IF YOU AIN'T LICENCED - GET A TECHNICIAN!

Many Thanks
williewonka
mapman's avatar
mapman
22,198 posts
 
Pack,

Are you referring to mu-metal for example?

I use mu-metal foil shielding around my phono step-up transformer to keep hum and noise levels down. Works like a charm, cut and dry, easily audible to anyone save the hard of hearing perhaps! No weird science involved whatsoever.
gvasale's avatar
gvasale
99 posts
 
Faraday cages are somewhat difficult to fully implement & can be unsightly, However, I once had a customer which because of lack of space needed to put one component of top of another & I used some aluminum foil to reduce hum.

Many solid state electronic devices are totaly enclosed in metal or have metal screened openings for ventilation. Not quite as necessary for analog as for digital devices unless you live in a metro area with either a radio station or some large computer installation close by. Digital devices tend to radiate elcetronic noise as opposed to analog unless you're talking tv. I don't even notice too much noise from the oscillators in am radio.
rodman99999
6,131 posts
 
I've used this stuff for decades, with great success: (http://www.emsclad.com/examples/emi-rfi-shielding.html), puchased here(page 14): (http://www.percyaudio.com/Catalog.pdf) Looks like production has stopped on it though. I guess I'll be using the Stillpoints sheets, for the next projects.
ptss
1,964 posts
 
Rod, how do you use the TI SHIELD? What size sheet?
rodman99999
6,131 posts
 
I have an unfortunate(cramped) home listening environment, that requires my equipment to be arranged in a cabinet/rack, one component above another(shelved). I'm using sheets of TI Shield under and/or above every component, to block emissions. I've also surrounded my power supplies, when feasible. I bought mine from Michael Percy Audio, who then supplied 12 X 24 and 12 X 48 inch sheets.
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