On 31/03/2016 3:30 AM,
wrote:
On Tuesday, March 29, 2016 at 6:58:21 PM UTC-4, Trevor Wilson wrote:
**Now you're being silly. Measure a fuse sometime. The resistance
increases, as current increases. It acts as a non-linear resistor.
The ONLY place for a fuse is before filter capacitors in an
amplifier. In the DC lines, or the speaker lines, fuses introduce
distortion and should not be used. This is electronics 101.
Silver-link fuses using an eutectic formula add negligible resistance
within their ratings. Nor are they cheap. As you well know, silver is
the closest thing to a super-conductor at any reasonable operating
temperature as exists in nature, much better than copper (or gold),
and so such fuses ought to be considered.
**Perhaps.
Example: I keep speakers from a current manufacturer that would cost
me well over US$7,000 to replace today. A few bucks on fuses to
protect this investment is well worth it. That I researched
dual-element silver-bearing fuses to minimize any downside from
adding such a device makes the choice both worth it and (probably)
wise. A defective amp is not likely to gradually ramp up into the
speakers, it is likely to surge - at least in my experience. So, I
can run the fuse very close to the overall speaker rating letting the
dual-element section handle high musical peaks without sacrificing
(much) protection.
Keeping in mind that as you suggest, low-resistance speaker
connections are a 'good' thing, I use #12 fine-stranded (19 strands)
THHN wire for speaker leads, spun in a drill to reduce capacitance
does well for short runs and is remarkably cheap at ~US$0.27/foot
(both stands included).
But, a fuse on a $3,500 speaker?
Wouldn't you?
**I am 62 years old. I've been listening a sound system since I built my
first one at age 17. In my 20s, I purchased my first home and proceeded
to assemble a sound system to please myself and my friends at various
parties. It also drove my neighbours a little nuts. This is the
amplifier I used to drive my KEF transimssion lines (rated at 50 Watts)
at many, many drunken parties:
http://audio-database.com/MARANTZ/amp/model500-e.html
I still own the best, but no longer use it. I certainly don't operate my
sound system at the kinds of levels I once did. I also use vastly more
sophisticated amplification nowadays (soft clipping, soft current
limiting, etc).
In my entire 45 years of listening, I only ever damaged one of the B139
drivers. The reason the driver failed was due to poor assembly at the
KEF factory. So, no. I would not put a fuse on a speaker of MINE. I
don't damage speakers. For all intents, I never have. For customers, the
situation is different. For headbangers, I will certainly suggest the
use of polyswitches or fuses, as the safety outweighs any potential
downside. I would certainly not install a fuse or Polyswitch in any high
end system, unless the client and I decided it was prudent. I did so
with these speakers, after long consultation with a client however:
http://elac.ro/elac%20x-jet%203.jpg (exploded diagram of the mid/HF driver)
The HF element (equivalent to a Heil unit) had failed, after his
children accessed his hi fi) was not repairable. A new driver had to be
sourced at almost AUS$1,000.00.
So yes, I fitted Polyswitches to protect the drivers.
--
Trevor Wilson
www.rageaudio.com.au
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