If we combine my last two posts a little, and now know that I also measure a.o. electro magnetic field (which is the least one under our control), then it surprised me a little how much even a loose (!!) connection emits electro magnetic (EM) field.
It actually does not even matter whether the cable is connected or not,
it just radiates once it is connected at one end. This counts for your power cord, for the USB cable and for the Interlink (and maybe more, but I just want to say "for everything and all").
What I do not know is to what degree devices suffer from this. But anyway what seems to be important is that all you isolate may not isolate really at all because something wants to go through air anyway (a not connected cable is fully isolated of course).
But this also means that when we "isolate" something, we must do it at both ends. Or "around" the device we want to isolate. Now think why there is this Sw#3 *and* the PE switch at the Stealth PC. Hey, not that I could reason it out, but I sure made them at both ends because that is what it comes down to.
Now we need to have both switches engaged. Why ? well, this has to be about something going over PE (which is indeed just the same as the neutral, which is ... just your power supply signal), and this is this analogue backdoor.
My device in between those two switches (which is now the NOS1a/G3 up to its analogue outputs I'd say), is still isolated. And the more I do that, the more the influence - now just originating from the PC of its own - must go via the mains.
Theoretically this implies a "draw" on the outputs of the DAC, which impy a "reversed" impedance to the D/A section. Thus, something is hammering on that impedance from the outside now, and any impedance change might be able to change the D/A process itself. You could even call it jitter, because it may cause the D/A "gate" to open a bit sooner or later. Say that current leaks through in reversed direction. Now THAT kind of jitter would be new !
And so I think that I just found something important. The missing link. Something which shouldn't influence so largely because it should disappear in the massiveness of high voltage (like 200uV of distortion should not be able to influence devices which run at 115V/230V). But it should imply jitter via that same backdoor.
OK, if I see radiation of 0.5V/m spouting out of everything, why shouldn't that influence fragile voltage stuff like a D/A conversion ?
And I
suppose some other way around : why wouldn't that radation be
less when the capacity (so to speak) is fully utilized ? This is just wild guessing. But I have something like : if radation (EM) emerges because of something not being able to go anywhere (a loose-end cable), then there should be no radiation when all is 100% connected. But not only connected - also fully consumed (no losses).
This is a bit of the opposite of isolation, but alas.
Peter
