2. amps-preamps
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What's going on with Synergistic Research fuses?

I live in California and a couple of weeks ago we had strange lightning storms that started the many fires burning in the State.  It also fried the fuse in my Pass XA30.5.  I got the amp second hand and it came with a SR Blue fuse.  I called Pass and they recommended a very cheap fuse which I ordered and installed.  Because I was curious, I took the SR sticker off the old burnt out fuse and found that it was a very cheap SIBA brand fuse underneath.  It is clear that SR is either not making the ceramic casing for this fuse or using the SIBA fuse and then doing stuff to it.  At the very worst, it's just slapping a sticker on it and charging a ton more

The thing is, I'm pretty sure I could hear a difference for the worse when I installed the cheap glass fuse post lightning storm.  Could it be that SR is modifying an existing fuse to make it sound better?  Maybe some more technically minded folks here on the forum could help me understand

thanks!
adam8179
atmasphere's avatar
atmasphere
12,097 posts
 
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.                       
mapman's avatar
mapman
22,667 posts
 
I observed fuse contacts needed to be reset periodically with most Japanese made amps/receivers back in the late 1970’s. Unregulated power supplies I suppose? It was the first and easy thing to check when a customer brought a unit in with a sound problem before sending for service. The fuse itself was fine.

Not all circuits are created equal. Beware of any claims that a fuse always makes a difference especially when due diligence is not performed before resorting to spending a lot more money on a nebulous at-best product.

Also note there is a big difference in construction of a slow blow fuse versus fast blow.   Slow blow usually has more to the filament to start.   Slow-blow seems better but remember the two are not necessarily interchangeable case by case.  Quality devices are  designed to function properly with one or the other.
georgehifi's avatar
georgehifi
10,312 posts
 
The OP asked if something was done to the fuse because it does sound different.


You’ve been told, it’s not the fuse, but the way it’s seated in the fuse holder that gives a very small voltage drop across the fuse (unlikely detectable)

To the OP adam8179
If it worries you just do a clean, up and push the fuse clamper together a bit to give it better holding tension. And use a new 10c fuse if it looks like these
Also the standard fuse could have had many turn on cycles, and become crusty, hardened and carbonized.
Left to right aging same fuse https://ibb.co/SQ9WJLn
Right to left aging same fuse https://ibb.co/S6YXQGT
And don’t be gullible and spend $160 on 10c re-badged fuses

Cheers George
nonoise's avatar
nonoise
11,096 posts
 
You’ve been told, it’s not the fuse, but the way it’s seated in the fuse holder that gives a very small voltage drop across the fuse (unlikely detectable)
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. A single speck or mote of whatever will have little to no impact compared to using one of your standard fuses, which are made of the worse, almost non conductive witches brew of metals they can get their hands on (iron, zinc, tin, lead, etc) because they melt easier and not because they conduct.

I know of no one who’d use these metals in their PCs, IC, and SCs.

All the best,
Nonoise

georgehifi's avatar
georgehifi
10,312 posts
 


Just "allnoise", snake oil and voodoo 

 ALL TOUCH CONTACTS GET SLIGHTLY CORRODED OVER TIME WITH DISSIMILAR METALS WITH CURRENT RUNNING THROUGH THEM
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