Sound and Proportional Q
The central feature of API 560 is its proportional-Q filter topology. Waves says the filter Q narrows at the extremes of the gain range, which it describes as a more forgiving sound when boosting or cutting strongly.
The EQ has 10 frequency bands from 31 Hz to 16 kHz, spaced an octave apart. Extra resolution is included in the ±4 dB region, where the developer says finer adjustments are most important.
An analog modeling switch adds subtle harmonic distortion and hiss. The output section includes a phase switch and a ±18 dB level control.






