Q Filter

A classic highly resonant 2-pole pingable filter based around a classic 4U Modular Filter design with HP, LP, BP and Notch outputs.

From the original Catalog

“The Variable Q VCF (VCFQ) is an excellent general-purpose VCF offering simultaneous Low-Pass, High-Pass, Band-Pass, and Notch (Band-reject) outputs. The resonance (Q) of this filter is dynamically variable by manual or voltage control. The VCFQ has two signal inputs. One incorperates an automatic gain control to prevent the filter from overloding at high Q settings. The second input has a level control so that the percussive effects of overloading the filter can be exploited. When a pulse is applied to the Trigger input, the filter will ring, producing a damped waveform similar to that produced by striking a resonant object. The nature of this ringing is controlled by the Q and the filter frequency. Percussive effects ranging from clicks to the sound of wood blocks and bell tones can be produced and controlled. This ringing effect can be used in conjuction with signals applied to either of the audio inputs to achieve highly controlled complex tonal qualities.
In addition to the three VCF's, the EXTENDED RANGE VCF (VCFX) which is identical to the VCFQ except it features a second sub-audio range. This low--frequency range allows use as a control voltage processor . A fast envelope or trigger applied to the filter in
the low range at high Q settings will cause low-frequency ringing, generating complex envelopes and damped vibrato effects . The VCFX can be patch programmed to oscillate by patching the band-pass output to the manual input . The outputs will be in quadrature relationships (90
degrees out of phase) . ”

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