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In article .com, wrote:

GregS wrote:
In article .com,
wrote:

Anyway, not sure what you mean by "changing a fuse should do a bunch
more than replacing a cord". Bunch more soundwise? Replacing one fuse
for the same fuse, or for that of a different rating? As mentioned in
my message, I didn't try replacing one fuse for another of the same
type, but for that of a different type. I did try reversing the amps
original fuse, and found that made an audible difference as well.

Many change the replacable line cord which does very little
in the big picture.

Yes, I know about that. I've changed line cords on tape decks,
turntables, etc.... always found significant differences. Didn't always
like the difference, since so many characteristics change. Not easy to
experiment with, unless you play around with IEC replaceable cords.

I do like soldered line cords. A line cord normally
has less resistance than a fuse, except slow blowing fuses under
1 amp will show definate resistance increases. The equipment should
be built to go around these issues and perform OK.

If you think you hear a difference, then a difference could possibly exist.

The difference is tremendous (to me), and I have no doubt it exists,
but then, I really didn't come here to prove that to anybody or debate
this issue (especially with those who have preconceived notions about
what can and can't be perceived in audio...)... only to find out what
the "real risk" was of substituting the fuse for something else that
would maintain the current, as the fuse did, but sound better. I don't
claim to have an engineering background, which is why I came asking
questions.

What I was comparing was the silver solder that I used in place of the
fuse (I dont nkow the percentage, but Im sure its very low, I nkow it
contains lead and its from RadioShack), vs. the wire filament in the
glass fuse tube. I'm thinking that if the wire filament is designed to
cut off the current during an overload or short by breaking from the
heat generated, would not the solder have the same effect of melting
during an overload and thereby cutting off the current and preventing
the amp from melting down or "catching fire"? The electronic solder
used does not seem to have a particularly high melting point, but I
don't know if it is much lower than that of a fuse filament. However, I
understand you to say most solders have high resistance, and that
resistance is what helps the filament in a fuse melt itself. Would this
not make it easy for the Radio Shack silver (probly mostly lead!)
solder to melt under overload conditions and prevent further damage?

You don't know what the fusing current will be, but it will be very erratic
using a piece of solder. It is likely to be in the 10's of amps to fuse
your solder. Fusing equipment is a little bit of engineering and a little bit
of practical testing. The exact value can vary. One thing for
sure, if any damage occurs, the insurance Co. could refrain from paying
you.

There is also the ladder effect. I once was sitting down and pushed a button, and a breaker
2 miles away tripped shutting down a complete satelite tracking station.
Its quite an experiance. I pushed a button triggering a 75 HP electric motor,
which shorted, tried to trip but fused the first breaker. This went to the next
really big big breaker. Can you imagine the silence and darkness having pushed
the button. It was really bright and very noisey with racks and racks of equipment
and air handlers until pushing that button. So if you have a fusing problem, it can escalate
problems at times.

greg

What I'm still unsure about is:

- What is the exact risk involved of changing the rating of a fuse (in
my case, 1.6a 125v for a 500mA 250v)?

Some fire potential. A fuse does not guarantee anything except current
overflow.

So you're saying even the RIGHT fuse installed does not guarantee the
amp wont catch on fire? Intersting, because all the crazy little boys
here have been screaming at me that my amp will send me and family to a
burning hell the minute I replace the fuse with anything but the rated
type. Some are even prearing hot dogs to roast at my family's
"personal barbecue", from what I've read.

You probably mean silver solder vs silver bearing solder. It does not
melt at too low of a temperature, but lower than copper. A fuse is made
to have resistance and cause heat melting itself. The lower the rating, the
more the resistance. Silver bearing solder could have at least 1 % silver
content. Most of the non-lead solders have a higher melting temperature,
but most solders have high resistance.

- How can I check to be sure my metal case is properly grounded?

It might have a 3 wire AC connector. Thats normally the only way to ground,
but
there are other ways. Most consumer audio equipment does not have a grounded
case. Grounding it may cause ground loop noise.

I guess my metal preamp isnt grounded then. Theres some kind of
grounding going on inside of it, but the plug is a two prong ungrounded
type.

In non grounded equipment, a voltmeter connected to a resistor and parallel
capacitor is normally
attached from the equipment to earth ground. There is a limit on passing
current,
normally less than 100 uA.