Steve’s MS-22 dual VCF

A dual voltage controlled filter (inspired upon a classic OTA design) 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 and is currently in a late prototype stage. Have a look at the teasers below.

Pictures

Videos

Specifications

  • General features
    • Dual VCF inspired by the Korg MS-20 OTA filter
    • Low-pass into high-pass 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 matte 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

Block schematic

Steve’s MS-22 filter topology
Steve’s MS-22 modulation matrix

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