- Sets the frequency range in which the filter moves.
- Switches between a lowpass filter or a bandpass filter
- Attack (1/2)
- Peak/Resonance control?
a 70's Electro-Harmonix brochure
The most flexibile controlled filter available offering the same rugged quality as the Doctor Q but on a more sophisticated level with greater flexibility and sweep. Additional controls allow for better fine tuning with maximum range of effects.