Squier Classic Vibe '60s Jazzmaster: Rhythm circuit

A lot of people wonder what the switch on the upper bout of a historical Jazzmaster (or Jaguar) is for. It engages the "rhythm circuit," which essentially runs the neck pickup through a different set of capacitors and pots, resulting in what might be described as a low-pass filter. It produces a mellow, "dead" sound that was intended to be used for jazz rhythm playing and was patterned on single-coil jazz pickups such as the DeArmond Rhythm Chief.
Most Jazzmasters (and Jaguars) no longer include this feature, but the Classic Vibe models do. This demo gives you a sense of what the rhythm circuit sounds like in a clean setting.
Strings: D'Addario flatwound Chromes, 0.011 (Jazz Light) set
Amp: Fender Champion 20, "Blackface" setting, gain at about 3.5, reverb set to about 3