A waveform has DC offset when its crossover points are other than zero.
That is, the entire waveform is moved up by the presence of DC current in the signal. When there is no DC offset (good) the waveform is centered around 0 and goes positive and negative from there.
It is typically caused by an electrical mismatch in the recording chain. This is typically inaudible.
However, in this discussion it is probably caused by a ground loop with a difference in potential of multiple grounds. In this latter case, you can hear a low level hum at 60Hz (and its harmonics such as 120Hz, 200Hz, etc.).
@maniac The P10 will remove DC offset on its output. It has a fairly sophisticated DC servo system built in that should remove any DC component on the output.
@admin Thanks Paul, I did not know about it (maybe good tip to add it to Powerplant specs )
I also have transformer hum problem on all my Electrocompaniet devices. EC is using some FTT technology (floating transformer) - could it be that this technology does not like regeneration from the P10? It’s audible on Sine and also Multiwave, but to be honest it’s slightly buzzing also when directly connected to the wall (that’s why I though I might have DC offset on my wall socket).
So I guess the next question is does it hum when it is plugged into the P10 but disconnected from the audio chain otherwise eliminating the ground loop? Guess you’ll have to “wait till your ship comes in.” ;))
Thanks elk I understand now . I always thought ground loops looked like a smaller wave over the signal .
But how does dc appear to be there in the first place ? Is this a change in the potential from output to input of different devices with separate PSU , s ?
Unhook the connections other than the AC to check for ground loops?
Yes, I will try a cheater plug when I come back from my cabin in the Norwegian mountains :)
The strange thing though is that the presence is irregular, at least wrt. intensity.
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