I'm pretty sure I know the answer to this but I have read and heard conflicting info so I'd like confirmation. A classic RC low pass filter (above) consists of a resistor then a capacitor to ground and the outbound signal is tapped at the resistor-cap junction. My question is does a resistor in series with the cap affect the filter corner frequency? (see tone control below) In the tone circuit below the RC resistance comes from the upstream circuit. Filter theory suggests no, the tone pot resistance doesn't affect the corner filter but it lowers the effectiveness of the filter--the corner freq stays the same but less high frequency signal is shunted to ground. Can one of you EE types confirm this?