QUALITY AND SECURITY OF "LITTELFUSE" PRODUCTS

At the risk of getting flamed by one particular fellow whose panties get quite wadded at the mention of Roger Modjeski’s name (apparently for not believing in the audible superiority of all audiophile boutique parts.), here’s what Roger found when he opened one of the eight Hi-Fi Tuning Fuses that were in one of his RM9 amplifiers returned to him for repair after the fuses had not done what a fuse is supposed to do when presented with a short: blow.

Roger discovered that the fuse was not designed for, capable of, or suitable for, use in a DC circuit---the very kind of circuit in which a tube operates. The customer’s RM9 had a tube fail, and the Littlefuse Roger installs in his amps would have done what a fuse is supposed to do when faced with a short in the DC circuit of a tube amp---blow. The Hi-Fi Tuning fuse did not, and the amplifier was then of course damaged. Not as a result of a fault in the design of the amp (unless you don’t want your tubes fused---Audio Research amps aren’t, ARC instead letting a resistor blow when a tube goes bad, thus requiring the resistor and any related parts to be replaced, rather than a fuse. At far higher cost, of course.), but because those fuses do not possess "high breaking capacity".

Surprised, Roger called first the U.S. distributor of the Hi-Fi Tuning Fuses, then the German designer/manufacturer. To his astonishment, neither knew what the term "high breaking capacity" means. That’s right---a fuse "designer" who knows less about fuses and their construction than an amplifier designer/manufacturer! The moral of this story is, if you are going to spend more on a fuse than a tube (if that doesn’t give you pause, spend on ;-), you might want to make sure the fuse is up to the task it is asked to perform in whatever application it is employed.

Sheesh! There are only two issues I myself addressed:

1- The claim of fuse directionality in an AC circuit is, as Ralph Karsten keeps saying, simply impossible. Of that there can be no dispute. None.

2- In the case of, yes Joe, one amplifier being damaged by the Hi-Fi Tuning Fuse being used in a DC application, the great electronics designer (there, I said it) Roger Modjeski of Music Reference received a returned-for-repair RM9 power amplifier. Upon inspection, Roger discovered that all eight HFTF that had been installed in the amp had failed to blow when presented with a short from a bad power tube---the very job they are intended to perform. Further, Roger, upon inspecting the fuses, found them to not be of high breaking capacity design, a necessity in the application in which they were employed. In conversing with the designer of the fuse and it’s American distributor, he learned that neither was aware of that term. Therefore, Roger warned the owners of his amplifiers (which have fused power tubes) against installing the Hi-Fi Tuning Fuse in his amps. That’s all. What’s the f’in problem, Joe? I had no idea letting people know about a potential risk in installing that particular fuse in a DC application would so upset you. I’ll never mention it again.

Roger does, however, approve of the Littlefuse brand of fuses, and infact installs them in his amps. They DO possess high breaking capacity, and were designed by an engineer who DOES know what the term means, and it’s significance, importance, and necessity in a fuse.

I said nothing about the sonic benefits of audiophile fuses, nor would I. That’s a separate discussion of which I have no interest in joining.