by m05iSo74BElAz6u3Wi » Sat Nov 19, 2022 5:12 am
It's just inverting the signal, a gain of -1.
If the filters are side-by-side (parallel), then the 0° setting has the two filters adding together. With the 180° setting, that signal is inverted, and in effect we subtract one signal from the other. That's what I think it is, anyway.
It probably doesn't matter with a the series connection... the second filter doesn't care, it just sees a signal coming in.