• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Ceramic vs Glass Fuses

ScooterMcTav

ScooterMcTav

I know less than I think
So trying to get a Rotel RB-976 up and running, and in checking fuses yesterday managed to break one of the ceramic 6A fuses.

Finding another 6A ceramic fuse locally is quite the challenge.

Am I OK to substitue a 6A slo-blow glass fuse instead? I can mail order a ceramic one, but looking for something to use until my order arrives.
 
Register to hide this ad
Was the original a slow-blow? - you must use the same basic fuse type as a replacement. If the original was fast-blow, you should not use a slow-blow to replace.

FYI ceramic fuses are tougher than glass fuses to withstand the energy of the fuse blowing. Ceramic fuses are often (always?) filled with sand - for the same purpose.
 
Yes, original was a slow blow (TT). Rotel service manual and fuse chart is unhelpful, as it lists to use a slow blow 6.3A fuse, but that's it.

This is one of the six power supply fuses.
 
Ceramic fuses are used on mains and high voltage lines for additional safety. A glass fuse can blow causing the interior to vaporize and deposit a film on the inside which can still conduct a small current heating the glass which will itself result in it becoming a conductor. Ceramic fuses are indeed filled with sand to prevent this event. Its your call but at least now you will understand what and why.
 
evoroadster said:
Ceramic fuses are used on mains and high voltage lines for additional safety. A glass fuse can blow causing the interior to vaporize and deposit a film on the inside which can still conduct a small current heating the glass which will itself result in it becoming a conductor. Ceramic fuses are indeed filled with sand to prevent this event. Its your call but at least now you will understand what and why.
Click to expand...
nice explanation . thank you .
 
I have noticed that the higher-amperage (10A, 12A slow-blow, 12A fast blow) fuses may not be available in glass, they're ceramic-only.
 
Just to tie off the thread, the explanation above was great. To see if it was running (under very little load) I temporarily used a 5A glass fuse. Then my ceramic fuses arrived at my door within 24 hours of ordering them and I swapped it up. But good to have the explanation - maybe this would make a good sticky?

Also wanted to give a shout-out to Digi-Key. Order was placed at 10:50AM on Wednesday, and the fuses were at my door IN CANADA by lunch on Thursday. And with shipping, 14 fuses (good to have spares, right?) cost me less than the 4 I found at Rat Shack. Sure, Digi-Key is in MN, but wow, that was fast. Plus the "BEL" brand fuses (which were the originals in the gear) were extremely affordable.
 
ScooterMcTav said:
Just to tie off the thread, the explanation above was great. To see if it was running (under very little load) I temporarily used a 5A glass fuse. Then my ceramic fuses arrived at my door within 24 hours of ordering them and I swapped it up. But good to have the explanation - maybe this would make a good sticky?

Also wanted to give a shout-out to Digi-Key. Order was placed at 10:50AM on Wednesday, and the fuses were at my door IN CANADA by lunch on Thursday. And with shipping, 14 fuses (good to have spares, right?) cost me less than the 4 I found at Rat Shack. Sure, Digi-Key is in MN, but wow, that was fast. Plus the "BEL" brand fuses (which were the originals in the gear) were extremely affordable.
Click to expand...
So, I had blown my speaker fuses (one of them actually) on my Hafler XL-600. The only ones I could find at the time were sand filled. I replaced the both fuses with the sand ones. They do not sound as good as the glass fuses. They may have the same values but they don’t sound the same when placed in the signal path. Sand/ceramic are great for the main power supply but I would never use them for the speakers again. Just thought I should share my experience.
 
Product catalogs from Littlefuse and Bussman are available at no cost from their websites. They contain explanations and data for each type of fuse they make. Except differences in sound passing through them.
 
DEAFASABAT said:
Product catalogs from Littlefuse and Bussman are available at no cost from their websites. They contain explanations and data for each type of fuse they make. Except differences in sound passing through them.
Click to expand...

Thanks! I forgot the more current, the more heat, leads to more resistance, leads to less signal. That translates into more distortion. I popped in 10amp fuses - sounds much better. God help my neighbors!
 
You probably already realize that there is an inductor in a thermo-magnetic circuit breaker (the type which is probably in your residential load center) which will also limit current flow and marginally decrease voltage as load increases. I suppose you've already thought of increasing the size of that as well, so that it doesn't degrade the sound of your equipment. It's always good to be able to enjoy your favorite selections while diving down the fire escape.
 
Ha! That is why we have a line conditioner hooked up to a Variac! Additionally, I don’t mind resistance on the circuit with the thermomagnetic device, since I only want 60hz from that circuit. However the speaker leads - I don’t want resistance at any frequencies.
 
Then you may as well just wire around the chokes and emitter resistors on the output transistors, because they are, after all, resistance. There is a phenomenon known as an "impractical truism" wherein general principles and rules are over-applied. That's what sells "sonic fuses" and "audiophile speaker wires" in most cases.
 
Watthour said:
Then you may as well just wire around the chokes and emitter resistors on the output transistors, because they are, after all, resistance. There is a phenomenon known as an "impractical truism" wherein general principles and rules are over-applied. That's what sells "sonic fuses" and "audiophile speaker wires" in most cases.
Click to expand...
It is called reductio ad absurdum
 
You must log in or register to reply here.
Back
Top Bottom