Originally Posted by arthurchino
pickup loading? tell me more..
The load a pickup sees makes a huge difference in sound. Usually a pickup sees the load from the guitars volume and the tone control. Under normal conditions (load is mostly resistive, like a tube amp input) it's effect is a resonant hump in the upper mids of the frequency band, somewhat like a mild parametric EQ. The load on the pickup (and the pickup, tone control, volume control and cable as well) set the frequency and gain of that hump.
This is the normal behaviour if the pickup sees is a resistive load.
Now I'm guessing: You have connected your passive bass to a DI box. If this box input is a transformer, the pickup wouldn't see a resistive but an inductive load. This could (!!) interact with the pickup in strange ways by building a resonant circuit from the cable, capacitor of the tone control and the transformer winding. Your ripping paper sound could be such a resonant oscillation.
A short sample of this sound would be usefull for diagnostic btw.
The easiest way to get rid of it is to use some kind of line driver between the passive bass and the DI box. It can be as simple as a single transistor impendance buffer or a stomp box in bypass (some of them have an impendance buffer even if turned off).
The active basses electronic does, among other things, the same. The pickup won't be affected by the load connected to the bass anymore. All it sees is the well defined load of the active "on board" EQ. Whatever you plug into the bass now effects the load of the active electronic, not the pickup.
Hope that helps.