The Marshall Valvestate VS100 has a "Power Dimension" switch. It seems like the circuit is supposed to emulate some of the characteristics of a tube output section. There's a phase splitter, JFET gain stages for the two signals to simulate phase inverter and/or output tube distortion, a differential op amp combining the two signals and finally a fixed EQ filter that looks somewhat similar to the impedance curve of a 4x12 connected to a tube power amp, although much more exaggerated, especially in the lows.
Anyway, this last filter is what I can't wrap my head around. If anyone cares to shed some light on why the frequency response is such as it is that'd be much appreciated
Power dimension circuit:
Just the EQ filter redrawn in LTSpice:
Frequency response of the filter:
Anyway, this last filter is what I can't wrap my head around. If anyone cares to shed some light on why the frequency response is such as it is that'd be much appreciated
Power dimension circuit:
Just the EQ filter redrawn in LTSpice:
Frequency response of the filter:
