Electrostatic speaker cables...

Audioengr: ""Propagation speed????? You must be joking. This is not a common-clock digital system. This is analog audio for kripes sake! Series inductance is the most important parameter, followed by capacitance and dielectric absorption.""

Yes..prop speed is important, but, not the entity itself..I explain:

Prop speed, V = 1/ sqr(LC), and also:

V = (lightspeed) / sqr(mu * epsilon)

And: L * C = 1034 * effective DC...l in nH, C in pf.

Measure L and C...you did, at 33 nH and 118 pf...your effective DC is (33*118)/1034...or, 3.76.

The prop speed is proportional to 1/sqr(effective DC).

So, the prop speed is definitely related to L: L being related to mu, wire diameter, and wire geometry....and C: C being related to epsilon, spacing, geometry.

I do agree that the term "prop speed" is rather confusing, as most seem to think it means that the transit time from the amp to the load is of any consideration...it isnt. But, the term prop speed is directly related to the DC, L, and C.

Audioengr:""If you need a low-inductance, low capacitance cable, Which you do, this is a hard combo to come by.""

Actually, it isn't hard. But, physics sets limits. I can easily make a cable which has .033 uH per foot, and about 35 pf per foot while keeping guage to about #12, but I'd prefer to keep the impedance at 8 ohms. That would be L of about .008 uH/ft..C of 135 pf/ft, diameter of about .4 inch with insulation 20 mils....or .6 inch dia with 40 mil insulation. It depends on your flashover rating requirement.

Cheers, John

Jneutron: What do you do about skin effect, conductor shape, EM field ( and therefore the impedance ) consistencies at various power levels, etc ??? I'd like to see what your "simple math" approach to cable design comes up with when all of the factors are taken into consideration. It is good to see that you recognize power transfer characteristics as being "important" though : ) Sean
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Cable design, category speakers... Hmmm, some background..

The only thing a cable is supposed to do is transfer energy to the load. Any storage of energy within the cable results in the load energy being slightly lagging.. This storage is both inductive, and capacitive, and both mechanisms are lagging in nature, meaning eventually what is stored in the cable gets to the load, as the source is very low impedance...

So, to reduce this lagging storage, minimize both L and C. Unfortunately, physics gets in the way, and L and C have an inviolate relationship: That being L * C = 1034 * EDC...EDC is the effective dielectric constant, and is equal to the DC only for a coaxial structure composed of two cylindrical conductors to eliminate the inner conductor internal inductance of 15 nH per foot. For all other geometries, the effective DC can only be larger than the insulation DC..Ribbon geometries will approach this for very large ribbons with aspect rations greater than about 10. (aspect ratio being width/thickness)

The prop speed is directly related to the EDC, being V = C/sqr(EDC). (note that I neglect the term of magnetic permeability, that would make the denominator sqr(EDC * Mu). Measurement of the inductance already lumps that mu term into the EDC...If I called it "effective DC times effective Mu, it would just add to confusion since nobody(?) uses magnetic speaker wires)

So, minimize L and C the best you can, and the storage lagging mechanism reduces, and the prop speed goes up. And, as luck would have it, minimizing the cable storage happens exactly when the cable impedance is the same value as the load.

Skin effect:
Skin effect causes the storage of energy within the cable to change with frequency. At low frequencies, there is an inductance of 15 nH per foot within the conductor, which is added to the external inductance of the geometry of the two wires. As the freq goes up, this inductance goes down.

Skin effect is worse for solid conductors, and is less for stranded conductors..this is due to the fact that strand to strand conduction is less than that of a solid. When the radial conductivity of the conductor is compromised, skinning is LESS..so, stranded wires will have a little more inductance than solid, but we're talking about at most, 15 nH per foot..this is only 18% of the total for a #12 wire pair.

The conductor shape will affect capacitance and inductance, shape should be used to minimize both..coaxial being the best, ribbons second, multiple pairs third, proximity last.

The cable which has the least effect on the soundstage, with respect to adding "something", will have an effective dielectric of 1, a characteristic impedance equal to that of the load, and will have sufficient guage to keep the damping factor high. All this is quite easy to do...the question really is...will people like the sound, or does every system have different needs..

But honestly, it's all in the R, L, C, and Q of the cable. Unfortunately, there's been so much mis-information spread around that high end audio guys end up guessing and trial and error, without much in the way of science..and, realistic measurement of matched Z cables is impossible for most wire vendors, as inductance measurements at the tens of nanohenry level are very difficult to do correctly.

Cheers, John

PS..pics and graphs woulda helped, but this ain't no diy.com.