The OBP-1 bass preamp's boost-only design gives you the tone-shaping benefits of active electronics without losing the inherent sound of the instrument. The OBP-1's discrete, all-FET circuitry features up to 18dB of boost at 40Hz and 4kHz, creating a sonic environment high in dynamic headroom and low in noise. Aguilar preamps have high headroom, low distortion and reproduce the full dynamic range of your instrument. A great upgrade for any bass!