What's going on with Synergistic Research fuses?

So, you would consider an expensive aftermarket fuse a Veblen Good as opposed to a Giffen Good

They might be both! Certainly its nothing I worry about.

but lets get the rest of it right, and may only apply to non regulated equipment.

Yes- I've been careful to mention this at least twice earlier. 

It’s all fuser snake oil voodoo, don’t try to make it anything else and give fusers even more fodder to twist around in their snake oil heads.

Using a generality like this is problematic- its better to say that *most* of its snake oil... the problem is that the effects are measurable. But there is also the Veblen Effect- that the fuse must make a difference because it cost so much (which is a subset of 'expectation bias').

if a piece of equipment, let's say a CD player, has multiple fuses, let's say eight of them, how does the improvement go?

The voltage drop across the fuse is the issue. I seriously doubt you would be able to measure or hear anything in a CDP, since many of them employ regulators in the various power supplies, and also since the voltage drop is very slight anyway.

I connected a scope to the speaker outputs and used a 1khz sine wave input and I replaced the fuse with the following:

- straight silver wire 12 awg (no change in sound, no change on the scope)
- straight 99.9% pure OFC copper wire 10awg (no change in sound, no change on the scope)
- standard Romex wire used in the house installation (12 gauge 20 amp circuit) (no change in sound, no change on the scope).

Even with a complete short circuit of the fuse there was absolutely no change in the sound and/or signal.

I am not arguing the results of your experiment.

However there are some uncontrolled variables. In the measurements I've made, they only seem to show up with equipment that actually draws enough power that you can measure a voltage drop across the fuseholder. You did not mention what amp you used, but I suspect it does not draw much power. The less power drawn the less measurable the effect of the fuse is and likely the less audible. The areas I see it making a difference are total power output. You'll need a variac to do this, since as the amp makes more power it will make a bigger voltage drop. You want to be able to change the input AC voltage to compensate for that so you can see what the amp does if 120V is present at the output of the fuse as opposed to when the voltage is at the input to the fuse. So you have to increase power to clipping, then measure the voltage on the output side of the fuse, readjust the variac, then readjust for clipping and so on.

Also measure the output impedance and distortion. Don't bother if the amp only makes 5 watts- the effects will be too diminished.


Using this technique I've seen how a power cord can rob an amp of nearly 40 watts- slightly less than 1/3rd its total power. But that amp has a significant filament circuit; if you are trying to this with a 20 watt solid state amp you're going to have difficulties measuring anything!

@danvignau  It appears you didn't read the first page of this thread:

As to why the fuse makes a difference, its easy to measure. Its the AC voltage drop across the fuse. Because fuses have to heat up in order to blow. as the amp is playing peaks, the voltage drop increases. The contacts on the end of the fuse make a difference too- which has led to the idea that fuses are directional (they aren't). Its just that sometimes the fuse sits better in its holder if you turn it around (although by simply rotating the fuse you can get the same effect, which can be seen by a reduced voltage drop across the fuseholder).

Quantum Tunneling

Anytime I see the word 'quantum' used in conjunction with audio I turn and run the other way as fast as I can.

I say the mains itself fluctuates more than this voltage drop anyway.

This is true, and is part of the reason that a system can sound better at certain times of the day. But its not just voltage- its also distortion of the AC sine wave on the line as transformers and rectifiers can react poorly to certain harmonics on the line, in particular the 5th (300Hz in the US).

You’ve been told, many times, that the way a fuse holder is shaped doesn’t change over time unless you use a hammer to remove and insert a fuse.

The problem is many fuseholders are not exact, but fuses themselves even less so. I've seen many where the end contacts were not concentric with the glass bit, on crooked and the like. Combine that with a holder that is not made perfectly and its really easy to see how shifting the fuse around a bit to get a better fit can affect things. How I do it is to simply measure the voltage drop across the fuseholder, then rotate the fuse until I see the lowest drop. Easy enough for someone that isn't going to zap themselves (which you can do easily enough, so don't mess with the fuse if the circuit is live).

But even this Ralph is null and void also, when the equipment has regulated supplies, as many "directional fusers" claim differences in fuse direction on their preamps and source equipment with regulated supplies.
As for them blowing for no reason, if indeed they do cryo them, this "can" make the fuse element more fragile harder/stiffer and suspect to de-rating it’s amperage and hence (blow earlier), a bit the opposite to what happens to us the older we get.

This has been my experience too. Our MP-1 preamp is heavily regulated so that the drop out voltage (overhead) is around 100Volts on a 117VAC line- so it can sag quite a lot without any change in the preamp's performance. And while we can easily measure a voltage drop across the fuseholder, no amount of changing the fuse has any effect on the preamp at all (and for the same reason, its very immune to power cord changes too).


But if you have an unregulated power supply as seen in most amplifiers, the fuse is probably going to have some sort of audible effect.                       

a completely new multi-stage high voltage treatment process for the lowest noise floor

Noise floor in a fuse? That is probably the thing that has to be explained.


We've seen some fuses that have a Teflon or similar sleeve around the fuse element, possibly meant to keep it from vibrating (if you watch a fuse as it sits in an amplifier circuit, you can see it move from the current flow through it). The problem with this is when the current of the element is exceeded, the metal is supposed to get white hot and fail- but the Teflon tube keeps it in place, allowing current to continue to flow. This can result in a plasma state, not really what you want a fuse to do at all!

 I guess I'm just interested in what they are doing to that cheap SIBA fuse to make it sound so good?

They are probably polishing the contacts, if the fuse is made by someone else. They might even be sending them out after that for silver plating.

Fuses don't act fast enough for surges, by the way. That's not their purpose. They are there to protect against shorts in the equipment, and as such they are kind of slow.

This statement is false. Having repaired many bits of consumer gear hit by surges caused by lightning strikes on the power grid, I've seen many blown fuses. When lightning strikes the AC power line, it can easily vaporize the fuse.

As to why the fuse makes a difference, its easy to measure. Its the AC voltage drop across the fuse. Because fuses have to heat up in order to blow. as the amp is playing peaks, the voltage drop increases. The contacts on the end of the fuse make a difference too- which has led to the idea that fuses are directional (they aren't). Its just that sometimes the fuse sits better in its holder if you turn it around (although by simply rotating the fuse you can get the same effect, which can be seen by a reduced voltage drop across the fuseholder).