wirespeed vs. frequency, Heaviside theory

[lopan]

frequency and wire speed.

jUst read this in an article by Ultra Audio

A fellow named Heaviside established a clever way of making the various frequencies traveling in a wire go at the same speed by balancing the speed-increasing effects of capacitance with the speed-slowing effects of inductance. This is called Heaviside’s Condition. Cables in which the ratio of conductance to capacitance equals the ratio of resistance to inductance (G/C = R/L) satisfy Heaviside’s Condition and may sidestep this problem (assuming all the other sources of distortion are controlled).

This is what MIT and Transparent are doing in their boxs but a couple things confuse me.

First can a capacitor actually increase the speed? Don't think so. Second does and inductor actually slow speed?

If (G/C = R/L) where G, conductance = 1/R then L/C = RR transfer into the frequency domain and LCss = RR or s = R/sqrt(LC). Certainly L and C are fixed in passive components but in a wire R varies depending on frequency and current depth and density but how much. L also varies as frequency rise the wire starts to act as a wave guide and inductance is minimize don't know what happens with capacitance.

Any thoughts are welcome.

Cheers

[454Casull]

I had no idea current propogation speed could depend on L/C.

[MarkMcK]

This is a language and thinking problem. Phase (or lag) caused by reactance in steady state testing is being confused (accidently or on purpose) with speed/propogation velocity.

I suggest ignoring such heavy discourse.

Mark

[brummkreisel]

The misunderstanding seems to be due to the difference between phase velocity and group velocity in the presence of dispersion which is affected by L and C. Ever heard of group delay? Same story. Check out google using those key words.

This problem arises, if at all, in high-L cables which have a HF response rolloff affecting group delay in the audio band (as does any filter). Use a PC-SCSI cable for your tweeter connection, and your bats will be happy again. (Oh, yes, your tweeter also has a HF roll-off. Woops.)

Cheers,
bk

[lopan]

group delay exists once you approach and enter the stop band not in the pass band.

Nom. Inductance: .14 µH/ft
Nom. Capacitance Conductor to Conductor @ 1 KHz: 28 pF/ft
Nom. Conductor DC Resistance @ 20 Deg. C: 1.07 Ù/1000 ft
Max. Operating Voltage - UL: 150 V RMS
Max. Recommended Current: 27.8 Amps per conductor @ 25°C

system resonance is at 1/sqrt(LC) = 80.4 million hertz generally for a minimium phase system we can say phase shift starts about a factor of ten from w. Since phase delay (in minimum phase systems) is porportional to the derivative of the phase, it starts with the phase changing at a factor of 10 of w. w/10 =8 million. A 10 foot length 80, 000

Well outside audio band. so that was a good thought but it doesn't calc out unless my math is wrong. I don't think so but it is 4 in the morning.

[Circlotron]

Originally posted by lopan
This is what MIT and Transparent are doing in their boxs

Certainly it's an issue if you are running analogue telephone wires between capital cities, but for the wire lengths commonly used in domestic hi-fi...

[Geek]

Originally posted by Circlotron

Certainly it's an issue if you are running analogue telephone wires between capital cities, but for the wire lengths commonly used in domestic hi-fi...

You underestimate the stupidity of the audiophool

[brummkreisel]

lopan: I meant really really high-L cables. But you're right, I should have been clearer than I was with my brief "if at all" statement.

[lopan]

you did say if at all

[DSP_Geek]

...about this stuff, then simply run RG-8 to your speakers. Low inductance, low resistance, sounds pretty darn good. If you really want to go over the top, and your amplifier isn't fazed by a bit of capacitance, try running four parallel RG-8s. WAF essentially nil, but the price is decent.


Francois.