The Electro-Harmonix Bad Stone is an analog phaser pedal designed for electric guitar and bass. It is based on the original Bad Stone circuit first released in the 1970s. The pedal produces smooth phasing effects ranging from subtle movement to pronounced sweeps. A manual mode allows the user to stop the sweep and fix the phase at a specific point. The effect is controlled with simple rate and feedback style controls. The pedal is intended for use in both live performance and studio recording environments.