The ZUUL’s threshold knob also controls the dynamics of the gate circuit. Perfect for guitar, bass or any signal source as it has studio quality specifications. Use in front of an amplifier or in a series effects loop. Dual colour LED for visual feedback gating action: Green = Open, Orange = Closed, Off = Bypass. The KEY input signal can be directly from your guitar (ex. split from ROACH or SPLIFF) or other signal source which lets you go from clean to high gain without changing the Threshold knob. This powerful feature lets you control the gate with a different signal than what flows through the input/output jacks of the ZUUL. Side switch (internal jumper or early versions) to change the threshold range to compensate for different input signal levels. Industry standard true bypass switching. Proudly made in North America.