Blowing a Brain Breaker

Every so often I read or hear about something that trips an internal circuit-breaker in my brain. That breaker is usually tripped by an urban legend, hoax, or flat-out un-truth. Something so off the wall, so out-there, so completely implausible that it overloads brain circuits and trips a brain breaker. You get what I mean.

Here’s the latest. I hesitated even writing about this, as merely doing so propagates the myth, but better to inform than not, so here we go. It’s called the HiFi-Tuning Fuse. That’s right, a fuse. The typically cylindrical object that goes into your gear on the power-line side of things that prevents the unit from catastrophic melt-down in event of some sort of failure. The same fuse that almost never blows, and if it does, can be replaced for about $1. Only this fuse costs a bit more: try $40-$50. For one. Of course, it’s a very fine fuse, hand-made in Germany with the finest of materials, ceramic, silver, and gold. That’s not the problem, no doubt it’s well made. It’s the claims that it makes a “night and day” improvement in sound!

A fuse is simply a piece of wire that is designed to melt when a certain amount of current is passed through it, encased in a protective package. There are variables that usually address how fast it blows when an over-current situation occurs. Slower is good if you get momentary intentional over-current conditions that you don’t want to blow the fuse. Fast is better if you only expect over-current conditions when there’s a critical failure, and want to quickly protect other devices in the circuit. By its very nature, a fuse must have a small resistance in it so that it gets hot enough to melt the conducting wire inside. The wire itself is usually that resistive element. However, the net voltage drop across a fuse is extremely small, usually equivalent to many feet of wire. And, it should be said that these days the time it takes to blow a fuse is an eternity compared to how fast solid state devices can blow up. The joke is, the transistor blows out to protect the fuse. It does happen.

That’s about it. Nothing more, nothing less. So how can this be a problem? I don’t rightly know. But the testimonials on the web site for the HiFi-Tuning Fuse seem to indicate an audible improvement when they are installed. For that to actually happen, the new fuse must have change something electrically in the circuit. It must have different electrical properties than a standard fuse. What could these be?

First is resistance. A fuse must have some resistance to work as a fuse. The current causes the fuse wire to heat and melt…and that happens because of a small amount of resistance. It’s very small, though. For example, a 2A fuse run at 2A will have about a half volt drop across it. Your power line voltage swings around more than that on a daily basis. Oh, and lets not forget that 60Hz power line voltage changes direction and thus instantaneous voltage continuously…at a 60Hz rate.

Next is inductance, again very small. In fact, the power transformer the fuse is in line with has much more. There are no published figures, but as you will see, even a few mH of inductance won’t matter in the long run. Read on.

Last is capacitance. There are also no published figures, but it can be assumed that it is quite low, or a fuse would produce AC leakage, not a good thing. Again, insignificant.

So much of electrical properties of fuses. What about the “audible effect” they have? Lets consider where they are in a circuit. A fuse is usually placed in line with the AC power cord, just ahead of the power transformer or power supply. No audio, video, or computer circuit uses 60Hz AC power line voltage directly. It must first be changed to one or more DC voltage power supplies. To accomplish this in a simple analog power supply, you need a transformer to step-down the power line voltage, then a rectifier to change the AC to DC, then a filter to smooth off the resulting ripple, then a regulator to further smooth and stabilize the DC voltage. What you’ve built in a power supply circuit is something that is, by nature, designed to ignore fluctuations of voltage on the power line, first as 60Hz, but beyond that, voltage variations, impulses, sags and surges. Within limits, a well-designed power supply will keep its equipment running even during a 20% brown-out. So whatever variation a fuse introduces is more than compensated for in the power supply. Switching power supplies are used in a lot of equipment today to eliminate or reduce the need for large power transformers, but they serve the same function…produce a stable, smooth, noise-free DC voltage regardless of power line frequency or voltage fluctuations. (Are you starting to question the need for power conditioners? Hmmm!) By the time the power line AC is converted to regulated DC, the miniscule effects of power cords, fuses, and hospital-grade AC plugs are long since swamped out.

That’s my electronics theory on it. A fuse can’t have an effect on the sound or picture of a piece of audio or video gear. Now here’s my challenge:

If someone, manufacturer or otherwise, would like to send me a sample of their fuse to test in my equipment and lab, I will do so and report on the results. If it is, as claimed, a “Night and Day” level improvement, I’ll not only say so on this blog, but I’ll also sign up to become a dealer for the product, and advertise it for free on my web site. However, if it does not live up to the claims, I’ll also say so here. I’ll even return the sample, postage paid. I will take every precaution during testing to insure the fuse is not blown.

To be completely fair, the manufacture’s web site on this high end fuse makes no direct claims as to what it does, only that it is a precision manufactured item, which not doubt, it is. The claims are in the form of testimonials from reviewers and users. Care to win over a skeptic?

There it is, the gauntlet is laid down. Not as dramatic as the “Amazing Randy’s” challenge about cables, but laid down none the less.

Any takers?