Four jumper caps A, B, C and D provide hands on control of bass and treble in this audio tuning module. The caps and jumpers are used to set limits and ranges for the sound. How it works - Jumpers A and B define the bass range. A for the lower bound, B for the upper bound of the bass audio range. - Bass adjustments - Removing the cap from Jumper A limits super deep bass and reduces distortion. - Removing the cap from Jumper B increases bass. - Installing the cap on Jumper B reduces bass. - Jumpers C and D control the treble range. When the caps on Jumper C and Jumper D are installed, the treble is at its loudest. Key benefits - Precise hands on control of bass and treble without software or external processors - Ability to reduce distortion by limiting very deep bass - Flexible bass tuning: boost or reduce bass to suit speakers and room - Simple mechanical adjustments using removable jumper caps What this helps with - Improves sound clarity on bass heavy tracks by limiting extreme bass - Prevents bass related distortion on speakers that clip at high levels - Tailors treble output for better balance with your listening environment Use scenarios - Home stereo in a medium room: tune bass depth and treble balance for smoother music playback - Bookshelf speakers in a small room: lift or reduce bass to avoid distortion while preserving clarity - Small venue or studio setup: dial in a clear, balanced sound for reference listening Compatibility and notes - Designed for systems that use removable jumper caps to adjust bass and treble ranges - Changes are hardware based and require no software - Some speakers may distort if bass is set too high; use A and B settings to stay within speaker capability