Re: Audiophools
- From: "Paul Hovnanian P.E." <paul@xxxxxxxxxxxxx>
- Date: Fri, 30 Jun 2006 21:34:33 -0700
"Roy L. Fuchs" wrote:
On Thu, 29 Jun 2006 16:52:07 -0700, "Paul Hovnanian P.E."
<paul@xxxxxxxxxxxxx> Gave us:
"Roy L. Fuchs" wrote:
On Sun, 25 Jun 2006 21:27:00 +0100, Eeyore
<rabbitsfriendsandrelations@xxxxxxxxxxxxxxxxxxxxxx> Gave us:
mc wrote:
Actually, silver-plating a power plug sounds like a good idea.
It does ? How so ?
Wouldn't it give a lower-resistance connection?
Teciicnally, adding some silver plaating would minutely add some resistance.
Not. Remember skin effect? Not that that even matters... The
transition region between the silver and copper will not matter...
either...
So, what is the skin depth at 20 kHz?
Dang.. couldn't find the chart!
http://en.wikipedia.org/wiki/Skin_depth
http://en.wikipedia.org/wiki/Skin_effect
http://en.wikipedia.org/wiki/Electroplating
http://www.audioholics.com/techtips/audioprinciples/interconnects/skineeffectaudiocables.php
audio stuff...
http://www.st-andrews.ac.uk/~jcgl/Scots_Guide/audio/skineffect/page1.html
Cool 50kW Transmitter output stage view here...
http://www.allaboutcircuits.com/vol_2/chpt_3/6.html
How does that compare to the
thickness of typical plating?
10Mhz is 21 microns. I think 20kHz is .2 mm
I found the formula:
Sd (effective) = sqrt( 2 / ( w * u * c ) )
where
w = wavelength
u = 4*PI*10E-7 (permittivity of space)
c = conductivity c of silver is 63.0E6 mho/meter
so I get:
Sd = 1.39 mm for Silver
Effective skin depth being the depth of a current traveling at the
conductor surface and zero through the rest of the conductor that would
give the same I*R drop.
The interesting thing is, given the above equation, the increase in skin
depth for copper is proportional to the square root of the ratio of the
silver to copper resistivity ratio. This is about 11%, so the copper
skin depth is 5% greater.
This means that a copper conductor will have to have a 5% greater radius
to maintain the same resistance per unit length.
Silver plating is like 11 microns for the good stuff, IIRC.
The really good stuff is "clad" not plated.
SPC is LOWER resistance than standard stranded copper wire.
True. But then all one needs is larger diameter copper to compensate for
its higher resistivity. Increasing the conductor diameter will increase
its self inductance, but do you really think that this change is going
to be significant?
A large gauge multi-stranded silver plated wire is going to have the
same proportion more silver in it (on it) as the smaller gauges. It
does make a difference.
Unless its Litz wire, plating the individual strands doesn't seem to
make much sense. The current will travel on the surface of the bundle.
If it is Litz wire, then the 5% increase in radius for unclad copper
applies.
--
Paul Hovnanian mailto:Paul@xxxxxxxxxxxxx
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