Aguilar OBP-3SK/PP Pre-amp/Rack Amplifier

Aguilar OBP-3SK/PP Onboard Bass Preamp — Three-Band EQ Built Within the Instrument

This onboard preamp places Aguilar's most flexible EQ circuit inside the bass's control cavity. Designed around a low-noise discrete FET input stage, the three-band layout reproduces the full dynamic range of any pickup. With the SK/PP layout, a stacked Treble/Bass pot pairs with a separate Mid pot — pulling the Mid pot out alternates between 400 Hz and 800 Hz, removing the need for a second toggle. Both 9 V and 18 V operation maintain clean headroom, and the preamp remains quiet enough for direct-in studio recording.

Push/Pull Mid Frequency — Dual Voicings from One Control

Distinct from other OBP-3 kits is the integrated push/pull on the Mid pot — one knob switches the center frequency between 400 Hz and 800 Hz with no external toggle or dip switch. Center-detent 50 K linear pots offer a tactile flat reference, while the 1 M 3 input impedance keeps the passive pickups' natural sound intact.

Low-End Control and Top-End Clarity — Shaping Warmth and Brightness

The Bass and Treble EQ controls live at the spectrum's edges with symmetrical boost and cut. Achieve everything from warm and full to sharp and articulate without needing additional pedals.

• Bass cut/boost: +/-18 dB at 40 Hz — essential weight without muddiness
• Treble cut/boost with a range of +/-16 dB at 6.5 kHz provides airiness for slap styles or smooths harshness effectively.

Midrange — Switchable Centers for P-Style and J-Style Sounds

The midrange band shapes modern bass tone, and this SK/PP variant delivers two distinctive centers without external rewiring. Pulling the Mid pot shifts the center between 400 Hz — fat and woody, akin to P-Bass — and 800 Hz — bright and honky, reminiscent of J-Bass. This setup keeps the control cavity tidy and preserves the original pickguard layout.

• Mid cut/boost: +/-16 dB at user-selectable 400 Hz / 800 Hz — changed via push/pull
• Freq selection method: push/pull mid potentiometer — removes the need for an external mini-toggle during installation

Signal Quality, Power, and Construction

Engineered to provide clean headroom and low-noise performance with support for both 9 V and 18 V power supplies, the analog front end delivers clear, quiet tone. A 25 mm × 25 mm board with a 165 mm wire lead fits into tight cavities, while the FET input stage keeps signal noise below -95 dBm unweighted.

• Input impedance: 1 M 3 — retains passive pickup resonance
• Operating voltage: 9 V or 18 V (18 V offers +6 dB extra headroom)
• The battery lasts for 324 hours on a single 9 V cell, allowing for extended playing sessions.

Intended Users

This push/pull-equipped onboard preamp suits bassists seeking studio-quality tone shaping inside their instrument rather than relying on pedalboards. Touring players benefit from its 324-hour battery life and low-noise FET technology across venues. Studio musicians appreciate the -95 dBm noise floor and 0.019% distortion for recording direct-in without engineer concerns. Alternating between P- and J-style pickups is simplified by the mid-frequency switch, which emulates both tones without external pedals. Those restoring passive instruments find that two knobs plus one push/pull control replace three knobs and a toggle.

Aguilar — Bass-Focused Electronics Made in the USA

Aguilar Amplification crafts preamps, pickups, and amps for bassists in the United States, with distribution through KORG USA. Their OBP-3 series remains the most adaptable three-band onboard preamp platform, offered in various wiring kits suitable for OEM factories and DIY installers. Every kit includes a three-year limited warranty against defects in materials and workmanship.