Features Preamp Board: This preamp board can adjust the input audio signal, and then send it to the power amplifier board. Smart Design: Equipped with dual 5532 chip, the pre amplifier module works with good stability and high efficiency. Simple Using: Compatible with 2.54mm and 5.08mm connectors, the output is DC12V, and frequency range is 20‑20KHz. Good Control: Enables continuously adjustment on treble, mediant, bass and volume, very simple to adjust as well. Easy to Install: Comes with M3 installation hole, the convenient installation can be quickly finished in minutes. Specification: Item Type: Tone Board Chip Model: 2 x NE5532, 7812, 7912 Input Voltage: AC dual 12V-18V. Structure: Dual 5532 high, middle and low, 3 sections continuously adjustable. Frequency Range: 20-20KHz Features: DC12V output, input and output 2 kinds of interfaces. Input Interface: Approx. 2.54mm / 0.1in interface, 5.08mm / 0.2in terminal. Output Interface: Approx. 2.54mm / 0.1in interface, 5.08mm / 0.2in terminal. Adjustment Type: Treble + Midrange + Bass + Total Volume Appearance Size: Approx. 100 x 43.5 x 23mm / 3.94 x 1.71 x 0.91in Mounting Hole: M3 (Diameter: Approx. 3.3mm / 0.13in) Package List:1 x Tone Board8 x Accessory Note:Compatible with 2.54mm and 5.08mm connectors. When using, only select one interface to input or output. Package List 1 x Tone Board 8 x Accessory