The voltage controlled filter is the prime method of filtering the harmonics of the input audio signals. The M²Synth has a number of filter choices:

• VC LPF 110 A low pass filter (attenuates higher frequency harmonics) with a 3-channel input mixer. Width 2U.
• VC LPF 116 A mini version of the low pass filter 110 without the 3-channel mixer. Width 1U.
• VC HPF 111 A high pass filter (attenuates lower frequency while passing higher frequency harmonics). Width 1U.
• VC BPF 113 A band pass filter that attenuates frequencies above and below the centre frequency passing only a narrow band of frequencies). Width 1U.
• VC BRF 114 A band reject (notch) that attenuates a narrow band of frequencies while passing frequencies above and below the centre frequency - opposite of the band pass filter. Width 1U.
• VC APF 115 A filter that passes all frequencies but varies the phase of the input signal at different frequencies in a non-linear way. Width 1U.
• VC SVF 112 A state variable filter that is 4 filters in 1 LPF, HPF, BPF & APF that can be used in combination of series / parallel for complex filtering effects.

Overview 

The voltage controlled 4-pole quad filter with low pass, high pass, band pass and an all pass filter commonly referred to as a state variable filter. Unlike many state variable filters, the 112 maintains a 24dB / Octave response and allows for individual CV control of each filter type. The HP, BP and AP filter input signals can each be switched between the main signal input or to the low pass output or switched off completely.  This allows for some rather complex filter sounds using a combination of series and parallel configurations.

Features 

• 1 Volt / Octave cut-off frequency CV for each filter type plus a common CV input that controls all filters at once.  
• Resonance potentiometer control with external CV control (controls all filter types)
• Each filter type has its own output
• A 4-channel output mixer blends the outputs of all 4 filter types to a common output
• Switches control the HP, BP and AP filter input route - off, main input signal or the LP filter output

Specification

• Supply voltage +/-12Vdc
• Supply current  +40mA / -55mA
• Waveform levels +/-5V
• Main PCB dimensions 131.95x174.05mm

Kit contents

Each kit contains

• Main PCB
• Jack socket PCB
• All electronics components, IC sockets and power socket
• 100mm long Power lead 
• Potentiometers, knobs, switches and jack sockets
• Front panel assembly (faceplate and 3mm aluminium back panel)
• Fixings