The OBP-3 is Aguilar's most flexible onboard preamp design, providing +/-18dB of cut and boost at 40Hz, +/- 16dB of cut and boost at either 400Hz or 800Hz and +/- 16dB of treble cut and boost at 6.5 kHz. The OBP-3 has multiple wiring options, and can be wired with either a mini-toggle or internal dip-switch for midrange frequency selection.