OBP + PIEZOS The OBP-1, OBP-2, and OBP-3 have only one input each. This means any blending of multiple pickups must be done outside the OBP preamp.
As a general rule, piezo pickups require a high impedance input of 1 megohm or more. The OBP series preamps have 1 megohm input impedances, so they can be used with most piezos. Some piezos require even higher impedances, so you need to check with the pickup manufacturer to make sure.
Passive magnetic pickups are relatively low impedances, and are designed to use 100k to 500k potentiometers. Active pickups are designed to use pots that are in the 25k to 50k range. So the problem is that magnetic pickup impedances are not compatible with piezo impedances.
The best solution is to have a buffer for the piezo before it combines with any other device. This way it can use the blend pots that are compatible with any magnetic pickup.
