Directional cables

Edited by physios - 03 Nov 2023 at 11:41am

I look at cable directionality in the same way as a piece of iron being magnetised by being put in a coil of wire and subjected to high voltage/current. It can permanently alter the dipole orientation in the metal leading to the potential for a slight bias in signal direction. I reckon it may subtly affect the timing of the signal rather than affecting the magnitude of the signal and the amount of bias is probably depedent on the frequency of signal being propagated. I say this because you can connect it either way around and it works fine; you'd measure the same voltages/currents either way but music signals are rapidly changing AC waveforms, not DC, so if there are any slight phase/timing shifts, it may be discernable after extended listening. Would be interesting if such a suggestion could actually be objectively measured with scientific apparatus.

It's common for the shield on studio cables to be connected to ground at one end only, a practice employed to eliminate ground loops.  I've spent a fair proportion of my career on HF transmitter sites working with the BBC and VoA; audio cabling in the control room is often grounded at one end.  The cables often run in close proximity to 500kW transmitters with no ill effects, so you should have no worries about the efficiency of the shield if connected in this manner.  By convention, the cable end closest to the audio matrix is grounded.

I have a couple of van den Hul cables which are grounded at one end only — the manual advocates connecting the ground at the signal source side.