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why do hi-end fuses keep blowing, while std don't?

I've had my McIntosh MC275 for several years running flawlesly. Up until last Nov I was using stock KT88 and rolled small tubes and had a Hi-Fi Tunning fuse without issues.

In Nov-13 I upgraded the KT-88 to Psvane black bottles measuring 60mA plate current. A few power-ons after I rolled the tubes, I turned on the amp to let it warm up, but returned to a blown fuse. I thought a tube might be bad so used a std fuse, but never had a problem again.

Two months ago I bought a new high-end fuse, replaced it, and soon thereafter the same happened: blown fuse. I replaced it with a std fuse again, which is still running.

So I want to upgrade the fuse, but chances are if I use the 2A fuse it will happen again. Yet I don't want to use a higher value fuse. I'm thinking the Psvanes might be drawing significantly more current than the stock KT88 and the Hi-Fi Tunning fuse might have a tighter spec, driving said fuses to fail while the std ones survive. Would you agree?

Suggestions as to how to resolve this?

thanks much!
lewinskih01
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geoffkait's avatar
geoffkait
23,365 posts
 
In the long history of audio there has never been a single documented and verified component damaged by a high end fuse. If anything, by blowing too quickly they prevent damage to equipment. What a load of horse hockey! 🏒 Are some audiophiles really that superstitious? First they complain audiophiles fuses blow too fast. They must have got bored with that approach and complain they don’t blow fast enough. đŸŽ»
bdp24's avatar
bdp24
9,703 posts
 

At the risk of being flamed, I'll remind everyone of the RM-9 amplifier Roger Modjeski received back at Music Reference after the Hi Fi Tuning Fuses installed by the amp's owner didn't perform their intended task when a power tube in the amp blew. Modjeski went into research mode to investigate the design of the fuses (including speaking to the German designer and manufacturer of the fuses), and reported his findings on his AudioCircle Forum.

I bring this up again only because directly above is the statement "In the long history of audio there has never been a single documented and verified (what's that mean? Modjeski's word isn't good enough?) component damaged by a high end fuse." I have no information of any other than that one instance, but Modjeski explained exactly why the fuse not only DIDN'T perform it's intended task (in it's application in the RM-9's circuit), but why it is INCAPABL:E of doing so (because of it's design and construction).

If one is sincere in desiring to learn what Modjeski has to say on the subject of not just the Hi Fi Tuning Fuse, but all fuses, all you have to do is go to the Music Reference AudioCircle Forum and read all about it.. Or, you can just get defensive, makes no difference to me. ;-) 

geoffkait's avatar
geoffkait
23,365 posts
 
I knew somebody would bring up Roger Modjeski, since that’s the only case anyone ever mentions. Thanks for accommodating me and reminding everybody! đŸ€— The problem is that somebody who hates aftermarket fuses and audio tweaks is the one reporting it. I put very little credence in that report. Besides, geez, that incident was so long ago as to be absurd. I assume there hasn’t been a similar case before or since. How long ago was it, ten years? More than ten? Who cares? As I am find of saying, amp designers are always the last to get the memo on fuses, power cords, isolation, just about anything that isn’t a circuit. It’s called having blinders on. 😎 Audio Circle was the perfect audience for that kind of nonsense, I will grant you that.
millercarbon's avatar
millercarbon
12,531 posts
 
I tried reading the AudioCircle Forum discussion on fuses. Modjeski is there and keeps talking about science, but after reading and reading never once did he mention any actual science. He did mention microphonics, only to say that can't be a factor but again without any actual science. When it got to where he was dismissing burn-in because nobody reported it prior to 1950, well totally lost interest. Only so much baloney I can take.

Possibly in spite of my initial impression the guy is not totally out to lunch. Don't know. What I do know, so much of what I saw is no better than any other guy with a keyboard and internet connection could do. So if you have a good link, something of actual informational value, please provide it.

Meantime, it is totally amazing how much improvement I heard immediately from just one SR Blue Quantum Fuse. Not that great at first, but reversed it and... awesome! One of them did blow on turn-on. Synergistic (well, technically high-end electronics.com) did replace it for free. After talking with Keith Herron we decided to go with a little higher value, and that one has been in there several months now. None of the others has blown. If any do, another call to high-end for another replacement. 
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