Steel-core Coax ??

[jneutron]

Of course it makes an audible difference.

Sheesh, why ask such a silly question...

Ok...parameters.

1. 30 pf per foot.
2. Dielectric coefficient 2.7 for teflon
3. Inductance per foot:

LC = 1034 DC

L = 1034*2.7/30

L = 93 uH per foot.

4. Z = sqr(L/C) = sqr(93000/30) = 55.6 ohms
5. Prop speed = 1/sqr(DC) = 60 % lightspeed

characteristic impedance..55 ohms. (hey, about 30 pf per foot is gonna give about the correct Z. This is the characteristic impedance without consideration of the core material. This will be the microwave prop velocity.

Ok, now for the steel core..assume it has a permeability of 100 (WAG)

L = 9300000

Z = sqr(9300000/30) = 556 ohms.

Until skinning occurs, the characteristic impedance of the cable is 556 ohms. As a matter of course, the characteristic impedance of the cable will track directly the permeability of the core material. If you use a steel of permeability 1000, the cable Z will be 5560 ohms..

Now, use one of these as an IC...bah, I'll post a link, put the numbers in and see where the break frequency is for the shield current..
http://www.diyaudio.com/forums/showt...22#post1672822
Just substitute the inductance of a typical length into the model instead of the .5 uH, use 6 feet of 9300 nH per foot, or 55 uH.


Fun stuff.
oops..forgot prop speed at audio frequencies..

EDC = LC/1034 = 269

prop = 1/sqr(269) = .06 C...6% of lightspeed..

Sheesh, whatta snail..
Cheers, John