@odman99999, Roger Modjeski has explained numerous times (both on his AudioCircle Music Reference Forum a few years back---which is still available to read, and on a recent thread that has unfortunately been deleted, perhaps by Roger himself. He may have also discussed the subject in his current thread asking for technical questions) why the original Hi-Fi Tuning Fuse (and ONLY that fuse, as that is the only "High End" fuse Roger has looked into) is designed and built in such a way as to not be able to protect an amplifier in the event of a tube failure in a DC circuit. Is has nothing to do with voltage or amperage, but rather the tube’s, as I said, design and construction, which Roger fully explains in his posts on the subject.
I myself need to go back and reread what Roger has said, but he provides info on how a fuse, any fuse, reacts internally when it "blows". That info should help people better understand why fuses are created the way they are, what the differences are between various designs, and why he warns against using the above fuse in specific applications. I really don’t see why Roger’s warning has been met by some with such hostility and defensiveness. That warning is well-founded, as a reading of it will make very clear.
The owner of the Music Reference RM-9 amp that came back to Roger for repairs did nothing wrong; he installed the correctly-rated Hi-Fi Tuning Fuses (9 iirc) in the amp, and when it was damaged sent it back to Roger for repair. Why he has been called incompetent is a mystery, part of the defensiveness and hostility I mentioned above. Roger fully looked into what had happened inside the amp, and has reported on what he discovered. He did some research on the fuse, and reports on what he learned about it. Is that a problem for you? If so, you are free to ignore Roger’s well-founded warning. Roger is also not incompetent ;-) .
