Master volumes

[jmcd]

Hi jmcd

1. You have to think of the MV as the signal source with a variable impedance. A 1M pot can look like zero or anything up to a maximum of 250k as an equivalent source impedance. Working against a 22nF cap, 250k allows response to 28Hz. If the resistance drops to 5R, then bass rolls off because the RC time constant is now extremely short. Adding the 100k provides a minimum RC time constant that is quite long and thus bass response remains relatively intact over the sweep of the control.

I still have difficulty 'seeing' how the resistance (of the MV or the additional 100k R) works against the 22nF cap. My understanding of high pass filters is limited to the various configurations of the circuit below, in which a series capacitance works against a shunt resistor that is on the output side of the cap. Now I surmise that a cap can also work against resistance on the input side of the cap. Is this the (or my) missing link?