Features: 1. The adjustment potentiometer is fully sealed type, and the input and output ends are made of pure copper terminals. The wiring is very convenient. 2. The IC socket can be soldered at any time to experience the effect of different op amps and improve playability. 3. Designed with LED indicators to monitor power status in real time. 4. The board is simple and beautiful in design, and the wiring is reasonable, which has a very high signal-to-noise ratio. This card has strong anti-interference ability. There is almost no noise near the horn when there is no signal input. Specifications: Condition: 100% Brand New Power Supply Voltage: DC10-24V Single DC Power Supply Frequency Range: 22Hz-300Hz Audio Input: Single or Dual Channel Audio Output: Mono Standard PCB Board: Approx. 78 x 32mm / 3.1 x 1.3in, thickness: 1.6mm Circuit board material: super hardness FR-4 fiberglass board Plate fixing hole center spacing: 70x24 mm, hole diameter: 3.2mm Potentiometer shaft center distance: 32.5mm Weight: approx. 32g / 1.1oz Package List: 1 x Filter Board 2 x Screws 2 x Gasket 2 x Knob Cap Note: This board is a heavy bass preamp board. It will not sound when directly connected to the horn. It needs to be connected to a pure final stage power amplifier board to create an active subwoofer. The power of the pure final stage power amplifier board is selected according to the shock level of individual needs. The higher the power of the pure final stage amplifier, the more shocking the bass effect will be. The so-called low-pass filter panel filters the high-pitched parts above the human voice, and keeps the low-frequency part to zoom in to improve the bass playback strength, and does not hear human voices and sounds of high frequency instruments during playback.