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 a push/pull on the Mid pot for midrange frequency selection.Amazon.comThe 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. The OBP-3SK/PP includes a stacked Treble/Bass pot and a separate Mid pot. The Mid pot is push/pull for Midrange frequency selection.Bass control: plus/minus 18 dB @ 40 Hz.Mid control: plus/minus 16 dB @ 400Hz or 800 Hz. User selectable frequency center.Treble control: plus/minus 16 dB @ 6.5 KHz.Input impedance: 1 meg ohmOutput impedance: 100 ohm 9 or 18 volts operation. Additional 6dB with 18 volts.Distortion: .019 into 10k ohm loadNoise: -95 dBm unweighted.Battery life: 324 hoursWire lead length: 6.50 inchesLow noise discrete FET input stage, center detent 50 K linear pots,with a dual concentric pot available.Dimensions: 0.98"W x 0.98"L x 0.59"DWarranty: Three year limited warranty.