Forgive me if this has been raised before. Most of the hum in a passive bass with mag pickups seems to come from the pickups themselves. You can see this by moving the instrument around in the interference and by the fact that hum from two single coil pickups cancels out to a large degree by being added out of phase when the balance is centered. So 1) how much improvement can you expect out of (electrostatic) foil shielding that has obviously NO effect on magnetic fields? and 2) what prevents a redesign of the circuit using lower resistance pots (and a bigger cap) to lower the whole impedance of the circuit and reduce electrostatic hum pickup that way? 3) where can I get data on typical Jazz pickups, the resistance, the frequency response, impedance at different frequencies, etc?