Jumper A and B control the bass frequency range. Jumper A sets the lower limit, while Jumper B sets the upper limit of the bass range. Excessive bass boost may cause speaker distortion. To reduce distortion, remove the jumper cap from Jumper A to limit ultra-low bass frequencies. Removing the cap from Jumper B increases bass output; with the cap installed, bass output is reduced. Jumpers C and D control the treble frequency range. With both caps installed, treble output is at maximum level. With only the cap on Jumper C installed, treble output is reduced. With only the cap on Jumper D installed, treble output is further reduced. With both caps removed, treble output is disabled. To use the crossover board: 1. Connect as shown in the wiring diagram (Treble, Low, Input). 2. Connect to your speaker system. 3. Ensure proper enclosure sealing. 4. Play audio and adjust jumpers for optimal sound. Typical configuration: Use Jumper A with Jumper B left unconnected. For treble adjustment, test different combinations of Jumpers C and D based on listening preference. Common configurations: - A + D: Enhanced bass response - A + C: Balanced treble and bass clarity - A + C + D: Clear treble and bass, with slight treble emphasis - A + B + C + D: Emphasis on midrange frequencies If bass output is excessive, remove the cap from Jumper A. Finalize settings based on auditory evaluation and secure the board to your speaker unit. Power rating: Up to 400W Impedance range: 4–16 ohms Frequency response: Adjustable via jumpers Color: Red PCB Material: ABS plastic + metal components Dimensions: 7 × 5 × 2.5 cm Package includes: - 1 × Crossover board Note: Actual product color may vary slightly due to lighting and screen settings. Dimensional tolerance: ±1–3 cm.