Dual 'Q' Filter

Audio Mixer w/ phase switch (3x1) (AMX)
[The Audio Mixer is a three-in/one-out manual mixer with a phase switch on input 3]

Dual Variable Q VCFs (2x VCFQ)
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 incorporates an automatic gain control to prevent the filter from overloading 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 conjunction with signals applied to either of the audio inputs to achieve highly controlled complex tonal qualities.

[With the inclusion of the HI/LO switch, the M-Class VCFQ is actually the VCFX, described below]

Extended Range VC 'Q' Filter (VCFX)

In addition to the three VCF's, Serge Modular offers an 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). 

Dual VCA (2VCA)
The DUAL VCA (2VCA) employs two high-quality VCA's. This module is an excellent inter-patch VCA, featuring very low noise and exponential response. It was designed as a small VCA function for use at various places within a system for internal VCA functions (as opposed to the VCA's for output mixing). Like the new Universal Audio Processor and the Cross-Fader this VCA has an audio taper that is an exponential curve with a 12 db per volt sensitivity throughout the range except below about .5 volts. Below this threshold, the output of the VCA will decrease rapidly to completely attenuate the signal. This response is perfect for our envelope voltage range and is responsible for exceptionally quiet operation. Control voltage rejection is very high, and the unit cannot be overdriven beyond a gain factor of two.

[Note that on this version of 2VCA, the top VCA is DC-coupled and the bottom VCA is AC-coupled] 

Mixer / CV Processor (3x1) (MPR)
[Note: Similar to the Audio Mixer (AMX), the Mixer / CV Processor's inputs and output are DC-coupled with blue jacks, indicating that they can process CV or audio. The other differences are 1) rather than a phase switch, IN 3 includes a single level and polarity control, and 2) the output includes a DC offset control.]