Subwoofer low pass filter module cannon tone board1. rectifier uses two 2200uf/25V a large capacitor to do filtering, op amp with large SNE5532, welded op amp IC seat, easy to replace the op amp to enhance playability, all Philips CBB capacitors are capacitors, potentiometers Taiwan produced using high quality sealed potentiometers. 2. the input / output interface board of A and B boards, user-friendly DIY, please indicate the time of purchase or B to A panel board, if not explain the default hair A board. 3. there are LED lights, real-time monitoring power status. 4. reasonable PCB line coupled with excellent choice of materials, basically no background noise. 5. Input voltage: AC dual 12v to 15v can double. 6. can be a single / dual-channel input, mono output. 7. PCB FR-4 ultra-hardness glass plate, specification: 78x42mm, thickness: 1.6mm. 8. frequency adjustment range 22Hz-210Hz, this frequency range is not the human voice, the so-called low-pass only the low-frequency output stage amplifier to be added after the amplifier board can be used. The intensity of the low-frequency performance and power amplifier board with matching speakers, please choose a different amplifier board and subwoofer (passive subwoofer) according to different occasions.