Q

If you come from the pro audio world, you may be used to Q referring to the width or narrowness of a peak or notch filter. In a synthesizer filter, when you increase the resonance (feedback), a peak forms around the cutoff frequency of the filter’s curve or shape. The higher the resonance, the higher and narrower this peak. As a result, some used to use the audio term Q to refer to the resonance amount, although you don’t hear that term used nearly as much today.