Feague

Four pole VCF and quadrature oscillator

The Feague is a 4 pole VCF and quadrature oscillator with 0, 90, 180 & 270 degree outputs. It is based on the design in Electronotes 41.
It features a Lo/Hi switch to run it at audio rates or LFO rates, plus a nonlinear Q pot which makes for interesting behaviour when using as a VCF.
When using as a QUO, the nonlinQ pot is used to increase the amplitude of the output signal, which is known to shrink somewhat at low frequencies in these kind of oscillators.

https://www.nonlinearcircuits.com/modules/p/feague?rq=feague