@microstrip: I was responding to andromedaaudio's comments about capacitors. I am not sure if he was addressing me or another poster.
Frequency range was DC to whatever upper end was deemed appropriate for the system. That would range from a low of maybe 100 MHz to a high of 100+ GHz, but most of my work targeted X-band systems (8 - 12 GHz) with an IF of maybe 1 GHz. I'd guess most measurements were taken to 20 GHz or a little above, many to 44 GHz (upper end of one of our standard HP/Agilent/Keysight VNAs), only a few above that. Highest I ever dealt with was a few things up around 110 GHz, and a brief sojourn around 300 GHz but that was all waveguides. As I said, these were primarily baseband systems using in-phase/quadrature converters so response to DC was required. To the front-end RF guys, X-band was often baseband and 1 GHz they considered "DC".
I am not really an RF guy, just worked around it a lot since I had to design or at least deal with the RF front end in spec'ing the data converters and associated circuits I designed.
As I said, these were not audio measurements, or at least not targeting audio systems. Measurements I have taken specifically on audio cables were much more mundane. Many of the cables were similar, with the caveat that virtually none were 75 ohm cables that are commonly used in the audio world (rader/ELINT/EW/com systems use 50 ohms almost exclusively, although CATV and video satellite links use 75 ohms). And as mentioned in my previous post I was assuming below -100 dBc was inaudible, or at least thoroughly masked by room noise, the music or movie signal, etc. I am aware some (many?) feel that too low a threshold.
microstrip, I am not trying to debate or prove myself credible to anyone else, just reporting what I found in the past and have acknowledged most won't understand nor care, and that it was not for audio systems. The main thing I wanted to highlight was that there are subtle things that happen in cables, but IMO they are too subtle to be audible. That said, I have not done a real controlled listening test, nor done measurements anytime recently that would bolster my position
vis a vie audibility.
However, since you do not find my experience credible for audio, what exactly do you think should be measured? The catch for me now is that my current job is focused on different signaling (computer stuff, SAS/SATA/PCIe/DDR) and we have no good audio-frequency test equipment so I don't have an easy way to do LF measurements. The VNAs, SA's, and such have LF limits well above the audio band, and I do not have fA and nV meters as I had back then.
