Then, how is this different from characteristic impedance? I have seen those curves and it isn't flat from DC to light but a huge S curve or something at low frequencies.
It is characteristic impedance.
The curves you see at low frequencies are incorrect...the belden one comes to mind. They tend to use wavelength as part of the lf characteristics, so the cable's resistance begins to play a huge part.
Remember however, the curves provided by belden (et al) all use approximation theory. For practical use at "wavelengths", those curves will reasonably mimic reality.
For audio, "wavelengths" as they apply to cables, is a useless entity, unless you want to talk about the practical applications of superconductivity...my forte'...
Cheers, John
ps...hey, where'd your post go??