Jumpers A and B control the bass range. A sets the lower limit and B sets the upper limit of the bass audio range. Jumpers C and D control the high range. When the caps on C and D are on, the highs are the loudest. How it works - If distortion occurs when bass is turned up too much, remove the cap from Jumper A to limit super-deep bass and reduce distortion. - If you want more bass, remove the cap from Jumper B. When the cap on Jumper B is on, the bass is reduced. High range adjustment - To increase the height range, leave the caps off or remove them as needed. When the cap on Jumper C and Jumper D is on, the highs are the loudest. Key benefits - Precise, user-adjustable bass and treble control using simple jumper caps - Quick, tool-free adjustments to tailor sound to your speaker and room - Helps prevent bass distortion while enabling bass or treble boosts as needed - Reversible and easy to reset to default by reinstalling caps Compatibility and use - Designed for speakers that use jumper caps A, B, C and D for range tuning - Works with units that provide selectable bass and high range control via jumpers Use scenarios - Scenario 1: Home stereo with bass distortion at high volume. Remove the A cap to limit deep bass and reduce distortion. - Scenario 2: Music with strong bass that sounds thin. Remove the B cap to increase bass, then adjust by reinstalling B cap if it becomes too strong. - Scenario 3: Dialogue-heavy films or treble-rich music. Put caps on C and D to maximize the highs. Tips - Caps are easy to remove or install for quick sound tailoring - If you need to revert to original sound, reinstall all caps onto A, B, C and D