Re: Adding a capacitor to a coil split to reduce brightness?
The resistor by itself will accomplish that because the way that the filters that make up the volume and tone controls work. Ignoring the inductance of a pickup to keep the math simple, the tone control acts as an RC filter. When the resistance is in series and the capacitor is in parallel, like our tone control, highs get dumped to ground. Increasing the size of the capacitor bleeds off more highs, but so does increasing the series resistance.
For example, lets take a PAF-ish neck humbucker with a resistance of 8kΩ and a .022µF tone cap. That gives us a filter with a corner frequency of 904.7Hz. Add a 470kΩ resistor in series and now our 478kΩ/.022µF filter has a corner frequency of 15Hz. Much more highs will be bled off in the second configuration.