The Electro-Harmonix Riddle: Q Balls is a powerful envelope filter pedal tailored specifically for guitar, offering tight and smooth control across an 80 Hz to 5 kHz frequency range for expressive auto-wah and “Q” filter sounds. It uses a fully analog circuit with switch-selectable analog distortion and numerous controls (Start, Stop, Attack, Decay, Q, Sensitivity, and Blend) to shape funky filter sweeps. An optional expression pedal input allows manual control of the filter sweep, and separate dry and effect outputs add versatility.