[RnB180]

So is this the basic understanding?

Interconnects rely on voltage moreso then current, thus spacing the conductors farther apart would lower the capacitance, but raise the inductance.

since capacitance plays much more of a vital role in interconnects since it carries a very small amount of current.

do you believe that the geometry the conductors in regards to spacing would increase overall fidelity of the signal? more importantly lowering the capacitance of the conductors?

Though after some reading, Ive read some cables purposely add higher capacitance to the signal. What are the gains of adding higher capacitance?

 

[peranders]

A cable is up to 20 kHz and 4 ft /1m a rather pure capacitor with low losses and what is important is how your signal source look like and the output impedance. If you have 1 kohms output impedance you will be able to drive the cable to -3dB up to 800 kHz.

If you have 30 ft/10 meters or more you must consider how you drive the cable.

You are right about that the geometry of the cable and used unsulation has great influence of the capacitance and the characteristic impedance.

Quote:

How does coaxial cable chacteristics define the impedance ? The length has nothing to do with a coaxial cable impedance. Characteristic impedance is determined by the size and spacing of the conductors and the type of dielectric used between them. For ordinary coaxial cable used at reasonable frequency, the characteristic impedance depends on the dimensions of the inner and outer conductors, and on the characteristics of the dielectric material between the inner and outer conductors. The following formula can be used for calculating the characteristic impedance of the coaxial cable: (formula taken from Reference Data for Radio Engineers book published by Howard W. Sams & Co. 1975, page 24-21) impedance = (138 / e^(1/2)) * log (D/d) Where: * log = logarithm of 10 * d = diameter of center conductor * D = inner diameter of cable shield * e = dielectric constant (= 1 for air) In a nut shell the characteristic impedance of a coax cable is the square root of (the per unit length inductance divide by the per unit length capacitance). For coaxial cables the characteristic impedance will be typically between 20 and 150 ohms. The length of the cable makes no difference whatsoever in regard to the characteristic impedance.

http://www.epanorama.net/documents/w...impedance.html

 

[Garbz]

My limited understanding is that there's a tradeoff in choosing capacitance.

Lower is better becuase generally capacitance is bad for these low level signals driving high impednace loads, aside from the fact it can also affect the frequency response of the equipment if the capacitance is signifcant enough.

But if you place the conductors far appart while capacitance is reduced, the chances of noise pickup increases. So if you live in a no-noise area I suppose far appart / low capacitance is ideal. Otherwise I think a little cap might be in order as it would reduce interference.