Steve’s MS-22 dual VCF module

Description

The MS-22 is a dual voltage controlled filter, inspired by the classic Korg MS-20 filter, with an innovative modulation matrix and one of the highest function-to-hp ratios in the land of Eurorack. This module was inspired by many pleasant chats with tech journalist Steve O’Hear.

What makes the MS-22 unique

The MS-22 contains two dedicated filter circuits, one low-pass and the other a high-pass. These are configured in series, the low-pass going into the high-pass. This configuration allows for a unique duophonic fighting resonance behaviour (see the demo video below). The cutoff frequencies of both filters can be CV’ed. Compared to most bread-and-butter MS-20 clones, the MS-22 is twice the amount of filter condensed down into half the package (4HP).

Furthermore, the MS-22 also possesses the following selling points :

• The MS-22 offers CV control over input gain, basically this allows you to either CV the level of filter overdrive or use it as A VCA for signal going into the filter
• The MS-22 offers CV control over resonance, the MS-22’s resonance can also be pushed way further compared to Korg’s MS-20
• The MS-22 has a link switch, which links the cutoff frequencies of the low-pass and high-pass filters in two different ratios. This creates two flavours of band-pass filters, of which the bandwidth can be tweaked and CV’ed. The switch itself also serves as an awesome performance effect as you can use it to create an instant drop. I demonstrate this near the end of this video.
• The MS-22 has a unique modulation matrix that allows to configure many internal patches without using cables. The modulation matrix is designed to encourage happy accidents!

Manual

Demo videos

Head over here for all demo videos.

Audio

The following audio demos are courtesy of Mr. Steve O’Hear!

Specifications

• General features
  • Dual VCF inspired by the Korg MS-20 OTA filter
  • Low-pass (12dB) into high-pass (6dB) configuration
  • Innovative modulation matrix allows CV control over all parameters
  • Cut-off frequencies can be linked, resulting in a band pass filter with controlable bandwidth
  • Bipolar monitoring LEDS for the LP, HP, resonance and gain CV signals
  • One of the best functionality-to-size ratios in Eurorack with a width of 4 HP and a depth of 45 mm
• Connections
  • Filter input
  • Filter output
  • Frequency CV input (FCV)
  • Auxiliary CV input (ACV)
• Controls
  • LP cut-off frequency (“frequency”)
  • HP cut-off frequency / BP bandwidth (“spread”)
  • Resonance : from mild to screamy
  • Gain : from warm to asymmetrical saturation
  • LP Frequency CV (FCV) attenuator
  • Auxiliary CV (ACV) attenuator
  • LP-HP link switch : 0%, 50% or 100%
  • Modulation Matrix switches, routing ACV to HP cut-off / spread, Gain and resonance : +ACV, off, or -ACV (inverted)
  • Calibration trimmers for the HP and LP filter are available from the side of the module.
• Modulation
  • Designed to work with unipolar +5V or bipolar +-5V modulation sources
  • Will also take unipolar and bipolar 8 and 10V modulation signals, but this results in a smaller usable range on the ACV and FCV attenuators
  • Low frequency and audio rate modulation of all parameters
  • Bipolar monitoring LEDs (green: positive, red: negative) for all CV destinations (LP cut-off, HP cut-off / spread, resonance, gain)
• Construction
  • 4 HP wide
  • 45 mm deep (skiff friendly)
  • High quality aluminum knobs with grippy surface
  • 2 mm thick glossy black front panel with white and metallic print
  • A tasty 4-layer PCB sandwich, containing 350+ components
  • Recessed power connector, avoids your power cable from adding to the module depth
• Protection
  • Reverse power protection
  • Buffered high impedance inputs
  • Output is protected by a 1K output resistor
• Power consumption
  • +12V : 100mA max
  • -12V : 100mA max

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