A cable forms part of an electronic circuit, together with the output stage of the component providing the signal, the input stage of the component receiving the signal, and potentially with a lot of other circuitry in those components as a result of the cable’s effects on the ground connection.
As with any electronic part within a component the sonic effects of the cable depend not only on its intrinsic characteristics, but on the interaction of those characteristics with the surrounding circuitry.
Here are some examples of how a sonic comparison between two cables can yield exactly opposite (or at least very different) results depending on the specific application:
1) If an interconnect having relatively high capacitance is compared with one having relatively low capacitance, and if everything else is equal, the higher capacitance cable will produce a duller and more sluggish response in the upper treble region if used as a line-level interconnect while being driven by a component having high output impedance, due to the interaction of cable capacitance and component output impedance. That interaction essentially resulting in a low pass filter, with rolloff and phase shifts potentially occurring at audible frequencies depending on the specific capacitance and the specific output impedance. While the **exact opposite sonic result will occur** if those same two cables are compared in a phono cable application while being driven by a moving magnet cartridge, due to the interaction of cable capacitance and cartridge inductance. The result in that case being a frequency response **peak** in the upper treble region.
2) Since the impedance presented by an inductance is proportional to frequency a speaker having high impedance at high frequencies, such as many and probably most dynamic speakers, will be relatively insensitive to the inductance of a speaker cable. While speakers having low impedance at high frequencies, such as most electrostatics, will be far more likely to be sensitive to it. That has no particular relation, by the way, to the sound quality or musical resolution of the speakers; it just relates to their sensitivity to cable differences.
3) It is easily possible for digital cable "A" to outperform digital cable "B" in a given system when both cables are of a certain length, and for cable "B" to outperform cable "A" even in that same system if both cables are of some other length. That may result from differences in the arrival time at the receiving component of signal reflections which occur at the RF frequency components that are present in digital audio signals as a result of less than perfect impedance matches, as well as cable-related differences in ground loop-related noise that may be riding on the signal, both of which can contribute to timing jitter at the point of D/A conversion. The happenstance of the relationships between cable length, signal risetimes and falltimes, cable propagation velocity, component susceptibility to ground loop-related noise, the happenstance of how closely the impedances of both components and the cable match, and the jitter rejection capability of the DAC, all figure into that.
A great many anecdotal reports that have been provided here and elsewhere over the years, in which digital cable performance has been reported as having been found to be length-sensitive, support that conclusion.
Regards,
-- Al
