I got 2 OBP preamps put into 2 different basses. A 3SKPP in a Spector rebop with emg hz pickups and a 3TKPP in Ibanez ATK with Nordstrand pickups. They were installed by a pro in a guitar shop.
I am experiencing the same problem in both basses. When i turn the bass or the mids up on the EQ of...