Theory of Audiophile fusing

I know nothing and want to learn the basics about fusing.

  1. Why are components fused?
  2. In theory why would an upgraded fuse improve SQ? Would this apply equally to digital and analog components. Why would I expect an improvement to SQ if an upgraded fuse is used in a power regenerator?
  3. Are some speakers fused, why?
  4. Does impedance, factor in, somehow to fusing?
    Thank you,

Very generally the fuse is there to protect the house not the equipment although your circuit breaker should do the same thing.
As far as SQ increase all that have done it says they are worth the money. I would be tempted to put a piece of copper the size of a fuse in there to see if it helped but that’s just cheap 'ole me.


There are some cases where the fuse is more to protect the equipment and not the house.

I think of the ribbon tweeters in Magnepan speakers, for example. They are delicate and fragile. Push things too far and the fuse blowing will prevent the ribbons from cracking out. Bypass that fuse, and it’s a couple hundred to replace the ribbons if things go wrong. (DAMHIKT - Don’t ask me how I know this.)


Chas -

  1. To keep large power swings from frying your expensive gear at the level of the individual component. Whether your house power fuses and/or component fuses will save all of that from a lightning strike…:man_shrugging:t2:

  2. It would do so IMO because any fuse in a component is a tiny filament designed to fry quickly to protect the device. Either side of it is much fatter wire. If the power wire was contiguous to the component, it would be unprotected. And a contiguous piece of wire from the power inlet to the guts of the device should theoretically sound better. Assuming you “believe” in that sort of thing. So anything more/better/different than the 10-cent fuse that is inline and came with your component has the potential to sound less bad. Much as “better” speaker wires sound less bad, or better power cords sound less bad.

Reminds me of a few years ago when lightning took out the transformer to part of our block and my house, which was on the telephone pole in my backyard. It was promptly replaced (!). The very next morning, there was another violent thunderstorm, and I was standing at the window looking out, and saw the strike that took the brand new transformer out…Again.

The morning after that, I was out in the yard when the power guys came by to check it out. The “fuse” on the 75kVA line is like a huge aluminum spike, between the supply line and the transformer. In the case of a strike it is supposed to melt prior to frying the transformer. But lightning can beat the best laid plans.

They only had one transformer left on the truck (having been driving around replacing stuff for days), and it was rated at +50% or so over the prior one. Fortunately for us, they were amenable to hooking this one up so they could go home. The power on our block was quieter and more stable afterward. No idea if that was luck/coincidence or what.

3), 4): dunno

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I agree with you. One can never have enough “protection” on their equipment (this post is going downhill fast). Quick example is the 3 channel Bose EQ I carefully put together. I’m still chasing a GND loop on the L & R channels but as of right now lifted the AC’s GND, which won’t break the GND loop but it does eliminate a “beat” frequency broadcasting its way through the box. There are two diodes and a 10kΩ resistor that breaks the GND connection all safely mounted on a PCB. The theory is even though GND is lifted, in the even of a short to GND, the IEC inlet should still blow it’s fuse while the high power Diodes/Resistor absorb the short. I inadvertently tested this the other day, and it worked like a charm. I I also put an industrial strength Full Wave Bridge Rectifier module which I’ve also tested :relaxed:

I would NEVER recommenend ANYONE use cheater plugs or GND lift circuits other than to temporarily troubleshoot GND loops.

Funny you use Maggies as an example. I’ve bypassed ALL the fuses in mine – I run an 800W (into 4 ohms) amp. No problems whatsoever, and the SQ improvement is significant!

Do fuses protect equipment from surges in either direction, internal or external to the component?

Do you need fuse if you’re using power plant? I would think the power plant will protect against everything right? Its fuse would go first under bad condition.

Thank you all. I have learned that the basic purpose of fusing is to protect equipment and your house.

Next question please, Is the operational design simply to put inline a weak point that it will burn or trip under an unacceptably high load?
Is there anything else that I should know about basic design?

On to the upgrade subject, I believe none of us spend without knowing whether or not the sound quality may improve. I think that one cannot buy a fuse with a warranty or free trial period. So, one has to have some very good information before purchase. Is this a correct thought?


Which is all I was doing, really.

I’ve bypassed mine as well. All one has to do is to be careful.

I believe that this thread is lacking in accurate information from the best experts. I suggest waiting for the PS Audio experts to get back on line after RMAF.

Thanks MarADyr, I am. I think the forum contributors always have a stimulating effect on the experts. Plus, there are some experts all around the world out side of PSA (I am sucking up here :grinning: ). I listen to all, both experienced audiophiles and experts, it helps my thought process.

As was stated above fusing is a safety issue: to protect your house from fire in the case of certain component failures and to aid in keeping 120V (or whatever) from being present in the case of a component that has some weird fault inside (like a knitting needle from a kid or being peed on by a cat.)

Fuses of necessity are non-linear devices (they have to act fundamentally differently for high current than low current) and any non-linear devices can affect audio in non-obvious ways. At the least they may modulate the current available based on the power drawn. Since hearing can at times have more resolution than approx. 1 part per million it’s sometimes possible that the small modulation caused by fuses to be audible. Nothing is perfect so even that modulation back at the regenerator might be audible. But more likely is that various fuses dampen high frequency garbage differently than 60 Hz AC. High frequency garbage travels much more easily along parasitic capacitances and inductances in devices. And non-linear components can modulate some of that high frequency hash into the audio band.

Some speakers may be fused to keep too high of a current demand from frying some part of the speaker, either in the cross overs or the drivers. Or potentially save your speaker wires or amps if there’s a short in the speakers.

It depends on how accurately you are using the word impedance. At the high level a fuse is a non-linear resistor, low resistance for low current and in the limit infinite resistance after too high of current for too long. Impedance is most accurately used to model the changes in phase and amplitude of a component/system at different frequencies. None of this is very useful in the typical modeling of fuses. (Tho as I alluded to above it might be subtly relevant for high frequency noise in audio systems.)

Re speaker fusing: a couple of decades ago we had a power glitch when I was using my system. When the power came back on the TV that was between my speakers had very colorful “rainbows” all over it. It had been “gaussed” by a high current flowing thru my speakers. One of the speakers was silent and it took a while to find that one of my speaker wires was melted like a fuse at one point. With a new speaker cable the amps and speakers turned to be fine and by turning the TV on and off a number of times the degaussing circuits slowly brought the display back to normal.


Thank you for your response, very helpful.