Aguilar OBP-3TK/PP Onboard Preamp Includes separate Treble, Mid, and Bass pots. Mid pot is push/pull for Midrange frequency selection. plus/minus 18dB bass at 40Hz plus/minus 16 db of cut and boost at either 400Hz or 800 Hz plus/minus 16 dB @ 6.5KHz Battery life: 324 hours