'High headroom, low-noise, 2-Band active onboard EQ preamp in two configurations voiced specifically for fretless basses with either active or passive pickups. Seymour Duncan Tone Circuits will add a tremendous amount of on-board tonal versatility to any dual pickup bass. Our design enables players to boost or cut specifically focused frequencies in order to achieve signature tones and to dial in a great sound no matter what the situation. We even added the two small trim pots on the circuit board can be tweaked to preset the frequency contour EQ just the way you want. The STC-2ASB and STC-2PSB Tone Circuits provides bass and treble controls, a master volume, a blend control, and our special frequency contour switch. These preamp were voiced by Steve Bailey to have two bands of focused EQ, together with a switch that engages a frequency contour optimized to bring out fretless harmonics as well as mid-range boost. The frequency contour is engaged by pulling up of the volume control. The STC-2ASB is designed to be paired with active pickups, while the STC-2PSB is designed to be paired with passives.The STC-2ASB and STC-2PSB will work in any fretless bass that is equipped with two pickups and has space for 3 control knobs (volume/freq switch, blend, concentric bass and treble controls) and a single 9v battery in the control cavity. Two 9v batteries can be wired together in series for added headroom. We include all necessary mounting hardware high-quality potentiometers on pre-wired harness, battery clip, and black anodized, knurled, dome-style knobs.'