Hier een link met een uitgebreide uitleg (Engelstalig) over impendantie in video- en digitale audiokabels en waarom het belangrijk is de juiste (voor S/PDIF 75 ohm) kabel te gebruiken:
http://www.bluejeanscable.com/articles/impedance.htmDit is het voor Marantzofielen belangrijkste gedeelte:
Because the effects of impedance mismatch are dependent upon frequency, the issue has particular relevance for digital signals. Where analog audio or video signals consist of electrical waves which rise or fall continuously through a range, digital signals are very different--they switch rapidly between two states representing bits, 1 and 0. This switching creates something close to what we call a "square wave," a waveform which, instead of being sloped like a sine wave, has sharp, sudden transitions (in practice, the "square waves" in digital signals aren't really quite square). Although a digital signal can be said to have a "frequency" at the rate at which it switches, electrically, a square wave of a given frequency is equivalent to a sine wave at that frequency accompanied by an infinite series of harmonics--that is, multiples of the frequency. If all of these harmonics aren't faithfully carried through the cable--and, in fact, it's physically impossible to carry all of them faithfully--then the "shoulders" of the digital square wave begin to round off. The more the wave becomes rounded, the higher the possibility of bit errors becomes. The device at the load end will, of course, reconstitute the digital information from this somewhat rounded wave, but as the rounding becomes worse and worse, eventually there comes a point where the errors are too severe to be corrected, and the signal can no longer be reconstituted. The best defense against the problem is, of course, a cable of the right impedance: for digital video or SPDIF digital audio, this means a 75 ohm cable like Belden 1694A; for AES/EBU balanced digital audio, this means a 110 ohm cable like Belden 1800F.
