Sub-filtering is bass filtering, that is, filtering out the bass, with less bass. Bypass on the power amplifier literally means bypass, English translation means bypass, and the effector means direct access; It is mainly used in the tuning and equalization circuit, that is, the signal bypasses the tuning or equalization circuit and directly enters the subsequent circuit, thus obtaining the original playback effect.

Bypass can be understood as surround sound in power amplifier sound effect.