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In Reply to: RE: fuses posted by DTS ma 7.2 on January 22, 2015 at 09:36:25
One more attempt to clarify what fuses do (or don't do) for speakers. First in the event of a catastrophic event (i.e. sudden high current event) a fuse should melt and leave a gap large enough that there is no arcing across the severed ends. The higher the voltage rating the wider the gap but this is independent of the current rating. With a planar magnet or quasi ribbon, the fuse element is definitely the weak link (as it should be) and will blow before the tweeter is damaged. That does NOT mean the fuse protected the tweeter as these tweeters are pretty tough and probably would not be damaged by short high current conditions. However with the ribbon tweeters which are much more fragile these may blow before the fuse -- it's all about which one gets to the melting point first.
Now with sustained high signals the tweeter may begin to heat up. However as the tweeter gets warmer the current flow decreases and the fuse, having less current will remain intact and fail to reach it's melting point. Hence no protection!
Everything else is antecdotal and not proof of protection. If you want to protect your tweeters wire in a low voltage light bulb, that way when the signal intensity increases the resistance of the bulb also increases with a resultant bigger voltage drop, thus protecting the tweeter. The tweeter will get quieter but not stop functioning and everyone is happy.
One other thing. Ceramic fuses are not less or more noisy than glass. They merely better contain any arcing which might occur when the fuse blows and therefore are safe in potentially explosive applications such as an operating room with oxygen or in a mine or other workplace with volatile chemicals.
Edits: 01/24/15Follow Ups:
Sorry, I don't believe you are correct, neo. ;-))
A long time ago, on one of my visits to the local RS Components warehouse for some fuses, the guy behind the counter suggested I buy ceramic fuses unstead of the normal glass ones I was going to buy.
He said that the traffic cops bought them for their radar guns, as they introduced less noise into the radar guns - and hence more reliable readings.
So I have stuck with them every since (for electronics, not Maggies).
Regards,
Andy
Jeez Andy, I didn't realize that. I guess on the basis of a RS guy (we all know how knowledgeable about electronics they are) I will have to change my ideas on ceramic fuses. Then again, I suspect the guys on the cable forum will say that the dielectric constant of the ceramic, being higher than air, adversely affects the signal. OTOH the Tweak Freaks probably could balance that by scattering some pebbles and crystals around the room.
Sorry mate, I am feeling a bit feisty today :).
Talking about noise, I see you are considering getting miniDSP's. I thought I read in this forum that they were noisy. I am not sure about that but I do wonder why you would want to convert the vinyl to a digital signal only to convert it back to analog again. Why not modify your analog xo's? Did I miss something in your post on Digital.
Yes, neo! :-)). My latest post will provide some more explanation.
Regards,
Andy
I have to write that one down.....for the next time I get pulled over in my Corvette. "Officer, I need to check the fuses in your radar gun."
I'll use that on the traffic court judge too. :)
I suspect there's more to this story than meets the eye. I would like to discuss it with the radar gun technician who supplied those Australian traffic cops. He was probably an audiophile. :)
Dave.
but it makes sense if, as I understand it, a standard glass fuse is just the wire in gree air ... whereas in a ceramic fuse, there is material around the wire?
Regards,
Andy
Hi. Andy;
I was also curious about ceramic fuses, so I "looked" inside one. This fuse is a "Ferraz Shawmut." It's hollow with NO material around the wire.
Take care....old guy
.
Neo, the 'vibration' guys like the ceramics because the active element is damped with some kind of filler inside the 'tube'. That's THEIR story.
For me? I'll simply delete the fuse and a bunch of extra wire and connections since I've not had ANY fuse problem with my 1.6s and before that the 1.5amp in my MG-1s popping was MY fault.
Also, aren't there a class of FAST BLOW and ULTRA fast blow, the fastest of which are used to protect the gates of delicate transistors in difficult to change or fix environments?
Too much is never enough
I wouldn't use a light bulb. A resettable polyswitch is the preferred device for protection if it is needed.
Here's a nice example:
http://www.parts-express.com/raychem-te-connectivity-rxe135-135a-polyswitch--071-264
Dave.
Hey, everyone knows that the purpose of the ribbon tweeter is to protect the fuse. :-)
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