Re: fuses on speakers
- From: Tomi Holger Engdahl <then@xxxxxxxxxxxxxxxxxxxx>
- Date: 31 Jan 2006 11:11:15 +0200
"exxos" <exxos@xxxxxxxxxx> writes:
> Hi all,
>
> I ran a amplifier via a fuse on the speaker and while the audio was loud it
> wasn't as loud as it should be, I took the fuse out (soldered over it) and
> the sound was much greater. For testing I also was running the mains input
> via a 2A variac (which I also took out). The speaker fuse was a regular
> 1.25" 2A and Variac was a small 2A type.
I don't think that a regular 2A fuse would have much effect on the
sound volume. Based on the data at
http://www.cooperet.com/library/products/GMA_Specs.pdf
it looks like a fast acting 2A fuse has less than 0.1 ohms
resistance and maximum of 250 mV voltage drop (this is when
it is heavily loaded). The other fuse types like slow flow etc..
could have slightly different resistances.
Those resistances of the fue should not have any great attenuation
on the sound. I think the small sound attenuation caused by the
fuse itse sould not be easily heard on the sound volume...
the difference in sound volue would be a smll fraction of decibel,
something so low that you could berely hear it, definately not a
great difference. The fuse may have some other aspects of
sound of the speaker, that coudl be heard or not.
If having the fuse at place has very considerable effect on
the sound volume, I quess that there would be some other reasons
for that than jut the fuse itself. Maybe the old fuse holder is
makign bad connection to fuse, and there is considerable resistance
there... that could have some considerable effect, both on sound
and heating of the fuse holder...
> Current was the mains was just over
> 1A so I don't think the Variac was causing problems there...
Using variac between maisn power and the equipment can have effect
that can be heard. If you do comparisions of with and wihtout fuse,
use the same powering setup (both times with or without variac).
> Which leaves
> the fuse limiting the power ?! I did manage to blow the fuse so power in
> watts must have been over 200watts....
Fuse starts to limit the power considerable when it blows up.
Before that the fuse power limitation is generally quite small..
There is some small resistance, that can get few times higher
bfore the fuse blows.
> Anyway, has anyone heard of strange things as fuses limiting audio power ?
I have heard strange things once when there was an old fuse
holder making bad connection and old almost blown fuse in it.
Repairing those got things right. Repairing in this case
included cleaning the fuse holder with help of contact
spray and some mechanical work. And then putting in brand
new fuse.
> I
> seem to recall reading a article a while ago that fuses on speakers was a
> bad idea or something...
Having fuses on the speaker line is not the best idea.
The fuse has some resistance.. and that resistance can change
somewhat depending how hot the fuise gets during the use.
> Also I recall seeing speaker fuses listed *as*
> speaker fuses... I wonder if they actually have to be a special type...
> anyone come across anything like this ?
I don't rememeber seeing anything that is listed as speaker fuses.
--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/
.
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