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Fuse Direction for Pass Labs Amp and Preamp

I am going to re fuse my Pass X250.8 and XP-32 with Synergistic Research purple fuses in a couple of days. I was hoping to get advice on a rule of thumb for direction of the fuses. My instinct tells me to start by installing the fuse by the direction of the lettering on the fuses. I am thinking that the direction should be the lettering left to right with the beginning of the lettering facing out of the amp and the end of the lettering facing into the amp. Does this sound right?

mitchb
twoleftears's avatar
twoleftears
5,360 posts
 

For your control group let me recommend these.

https://www.littelfuse.com/products/fuses/cartridge-fuses/5x20mm-fuses/285/285001.aspx

And yes, places like Mouser sell them individually or in small quantities.

atmasphere's avatar
atmasphere
12,418 posts
 

Would it be fair to say (or infer) that some of these boutique fuses are somewhere along the arc between a bog standard fuse and those FNM fuses? That they are definitely a step up but still nowhere near a FNM fuse? That could be why we hear a difference: they're simply a better made fuse, kinda like what you got with the FNMs. Just saying..

Some of the boutique fuses we've seen are inferior and some are OK so there's not a good answer to this question. We've seen some that employ a Teflon tube to damp the motion of the fast blow element; this type of fuse might not blow correctly since the metal can go to liquid and still be supported by the tubing- at that point would eventually become a plasma. I'd stay away from any fuses constructed in this manner. We've seen some that don't hold the current they are rated for and some that won't blow until you're a bit over spec! None of these are good situations. Having an equipment failure on this account wouldn't be a good thing so when people ask me about this on the phone I let them know what we've seen.

bdp24's avatar
bdp24
10,493 posts
 

Roger Modjeski (Music Reference, RAM Tubes) had a thread dedicated to fuses in his AudioCircle Forum. In it Modjeski disclosed what he had discovered during his investigation into some of the audiophile fuses, and how they compared to the Littlefuses he supplied in his amplifiers. One of the biggest boutique fuse makers went to work on the AudioCircle honchos, and Modjeski's Forum was closed. The thread is still available for reading, for those who are interested enough to search for it.

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