2. misc-audio
  3. 166294-93199

Is it safe to use a higher amperage rating fuse?

Today was my 2nd attempt at trying out Synergistic Research fuses.  About 3 years ago when I had separates, including mono block amps, I bought a set of Blue fuses.  One component had a mfg spec of 250mA and the retailer said go with 315mA.  My two mono block amps each had a 6.3A.  When I installed them one of them blew upon powering up.  The retailer said we should go up to the next rating.  I was a bit frustrated at the experience and didn't feel comfortable putting higher values in my expensive components.  I felt these expensive fuses should be made to tighter tolerances than the cheap BUSS fuses I had been using.  If I remember correctly, that was the actual argument that the dealer told me.  They are mfg to tighter tolerances so a 5A SR fuse was almost dead-on 5A while a cheap fuse may actually be 5.3A or whatever.  This also was a bit confusing at the time so I sent them all back.

Okay...3 years have passed and now I have a single integrated amp which has a 5A fuse.  Much less to invest in the upgrade so I ordered an Orange.  It came in today...installed....pressed power...on and off went the amp.  DAMN!!  I contacted the retailer and SR on the same email.  This was a different dealer from 3 years ago.  The retailer said I should go to the next value up.  I said no and and they are waiting for the tracking info of my return shipment.

I did a quick search of my question before posting and saw a thread about the Red fuses and someone said they had to do the exact same thing.  Is everyone putting higher rated fuses in their gear that is worth thousands of dollars?  Is there no risk in this?  I admit that I don't know what could actually happen from that.  It seems that other things could burn up if a higher amperage fuse is in place.  I am compelled to simply stick to the mfg specs for something that I don't understand because I don't want to create problems just from a simple tweak.

Should I let them ship me a 6.3A or just be done with this?
dhite71

Showing 5 responses by dletch2

dletch2
455 posts
 
When I installed them one of them blew upon powering up.  The retailer said we should go up to the next rating.  I was a bit frustrated at the experience and didn't feel comfortable putting higher values in my expensive components.  I felt these expensive fuses should be made to tighter tolerances than the cheap BUSS fuses I had been using.  If I remember correctly, that was the actual argument that the dealer told me.



This is what is referred to as a lie. Obviously they are not manufactured to tighter tolerances, reasons already given.


So what are you left with:

  • Fast blow marked as slow blow?
  • Poor quality control?
  • Up-marking the fuse, i.e. taking a 3A fuse and rating it 5A.  Why would someone do that?  Well that will make the fuse run hotter and will increase the fuse resistance. Bad thing right? Nope, More resistance in the AC line, and the noise will always drop a bit. Noticeable? Probably not.  When the fuse gets hot, the resistance goes up a lot. Noticeable? ... who knows.  But .. but .. but .. thermal modulation!   Well you don't want thermal modulation for a speaker fuse in a speaker line. In a power line that will give you even more filtering.

Don't you wish the manufacturer had their products validated by a 3rd party lab?  ... like any product that fulfills a safety function should be!   Probably it is .... by the company that makes it for $0.10 ...
dletch2
455 posts
 
Typical breaker has 3x or more the resistance of a fuse for a given current rating at room temperature. Audio is typically running at a fraction of rated power, so fuses typically are not even getting warm, and low power equipment normally has a fuse rated many times its requirement.
dletch2
455 posts
 
And here I just thought it was miss-rating and lack of quality control. 
dletch2
455 posts
 

clearthink1,213 posts04-28-2021 12:37pmdletch2"Typical breaker has 3x or more the resistance of a fuse for a given current rating at room temperature"

That may be accurate, true, and valid in you're country but it is completely false, mistaken, and wrong in many parts of the world and I even doubt it's truth where you live.



I see you are up to your lies again @clearthink.  Or should I say trolling.  Are you so obtuse to think it is not obvious?   You make this same response to my posts, we are up to what 5 now?  You NEVER back up your words with any facts. That would imply you are lying.   The question is, WHY ARE YOU MISLEADING PEOPLE HERE?    It does not matter where you live, breakers have more resistance than fuses. 
dletch2
455 posts
 
You can use a small value capacitor, 0.01 uF and smaller wired between live and ground to mitigate the noise.
Note, if you wire the capacitor upstream from the fuse, you have to use a capacitor that is rated to be used on mains I.e. a class Y capacitor. https://www.allaboutcircuits.com/technical-articles/safety-capacitor-class-x-and-class-y-capacitors/

Downstream from the fuse you can use a regular film capacitor.


If you connect a capacitor from line or neutral to AC ground, anywhere on the AC side, no matter before or after the fuse, use a Y rated safety capacitor. Where it is in relationship to the fuse does not matter. One of these small capacitors failing will not take out the fuse, it will just increase the leakage current to ground to a dangerous level. 

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