Jumper A and Jumper B let you tailor the bass range on compatible speakers. A sets the lower bound while B sets the upper bound of the bass audio range. If the bass is boosted too much and distortion occurs on some speakers, use these adjustments to stabilize the sound. - To reduce ultra low bass and distortion: remove the bridging cap from Jumper A. - To increase bass: remove the bridging cap from Jumper B. - To decrease bass: keep the bridging cap on Jumper B. Jumper C and Jumper D control the treble range. When the caps on both Jumper C and Jumper D are on, the treble is the loudest. Compatibility and usage notes - Designed for systems that expose Jumper A, B, C and D for direct bass and treble adjustment. - Simple hardware-based tuning without software or presets. Use scenarios - Distortion prevention in loud bass playback: if distortion is heard at high volume, remove the cap on Jumper A to limit ultra low bass. - Custom bass shaping: remove the cap on Jumper B to boost bass, or leave it on to reduce bass, depending on listening environment and preference. - Brightness enhancement: enable caps on both Jumper C and Jumper D to achieve the strongest treble presence. This configuration provides clear, hands-on control over bass and treble using only jumper adjustments, without changing the core speaker design.