Vintage Rickenbacker 330s included a 0.0047µF capacitor between the switch and the volume knob for the bridge/treble pickup. The capacitor filtered out lower frequencies resulting in a more trebly output. Some players credit this capacitor for creating the more vintage "jangly" tone as opposed to the much fuller sounding bridge pickup without the capacitor. A side effect of this capacitor was a volume reduction in the bridge pickup's output. This contributed to the need for the fifth control knob for balancing pickup volumes. The capacitor was removed from the circuit by the mid-1980's. A popular modification is to reintroduce the capacitor back into the circuit on more modern 330's, but it is usually attached to a push/pull potentiometer switch so it can be engaged by pulling up the knob and disengaged by pushing the knob back down - this allows for the more modern full bridge pickup sound as well as the thinner, more trebly sound.
