Feature: 1. Onboard bass frequency regulator potentiometer can make a relatively wide adjustment, so that subwoofer can be blend in the mid‑to‑treble harmoniously without a sense of violation 2. Dual 5532 2.0 full‑tone + 0.1 bass structure can control the volume of each channel of 2.0+0.1, adjustable bass frequency phase with powerful bass 3. Both full frequency and bass output signals have independent interfaces, which is very convenient 4. Support both DC 12‑30V and AC 9‑20V input voltage, powerful and practical 5. Made of high quality material with fine workmanship to guarantee a stable performance Specification: Item Type: Preamp board Chip Model: NE553278M12 Architecture: Dual 5532 2.0 full tone + 0.1 bass Frequency Range: Full tone 20-20KHz / bass 20-200Hz Features: 2.0+0.1 controllable volume, adjustable bass frequency and phase. Package List: 1 x Preamp Board