M 505

Voltage Controlled Multi Mode Filter

The MULTI MODE FILTER features low pass, high pass, band pass (12 dB/oct each) and notch mode (6 dB/oct), which are available simultaneously as well as combined at the mixed output, where the filter mode is voltage controlled. Cutoff frequency and resonance are voltage controllable too.

M 509

Low Pass/Band Pass 

Polivoks Type Filter  

The VOLTAGE CONTROLLED LOW PASS/BAND PASS FILTER is inspired by the filter part of the famous Formanta Radio Factory Polivoks synthesizer from 1982. 

It features a switchable band pass/low pass filter with voltage controllable cutoff frequency and as an enhancement of the original voltage controlled regeneration.

Filter slope in low pass mode is 12 dB/oct, in band pass mode 6 dB/oct.

M 517 

Coupled Dual Voltage Controlled

High Pass/Low Pass Filter

This module combines two VOLTAGE CONTROLLED FILTER circuits in one triple-width unit. The two identical filters are switchable high pass/low pass filters with independent controls for cutoff frequency and regeneration. 

The four-mode combinator allows using the filters as – two separate filters (”stereo mode“) – two filters in series (”maximum slope“) – notch/band reject mode – band pass mode. 

The balance between filter 1 and 2 and the bandwidth are voltage controllable. 

An additional jack combines both filters' audio outputs.

M 517 S

Voltage Controlled

High Pass/Low Pass Filter

The SINGLE VOLTAGE CONTROLLED FILTER is one half of the 517 module without the combinator part, featuring a single high pass/low pass filter with voltage controllable cutoff frequency and regeneration.

M 518

Voltage Controlled

Low Pass Gate Filter/VCA

The VOLTAGE CONTROLLED LOW PASS GATE is inspired by the
special module from Don Buchla found in his  famous “west coast type”
modular synthesizers (Series 200) from around 1970. 

The 518 module features a switchable combination of a low pass filter circuit with voltage controllable cutoff frequency and a VCA (here called “Gate”).

Both functions work separately or in combination.
The filter resonance ist voltage controllable.

The low pass filter slope is 12 dB/oct.