The Doepfer MS-404 MIDI Synthesizer

The Doepfer MS-404 is a MIDI-controlled monophonic analog synthesizer designed to be a rackmounted Roland TB-303 synth clone. It offers additional features, like MIDI and LFO’s, that give the synth additional flexibility.

The sound generating section of the MS-404 is 100% analog (VCO, Noise, VCF, VCA, ADSR, 2 LFO’s). Even the envelope and the LFO’s are pure analog and not simulated by software. Immediate access to all sound parameters is offered by 15 knobs and 6 switches. An external audio input enables sound mangling of other sound sources like samplers, digital synthesizers or expanders.

On top of that the MS-404 works as a monophonic MIDI-to-CV interface to control another analog synthesizer. The MS-404 is capable of controlling VCF frequency and VCA envelope amount (accent) via MIDI.

If you’ve used the Doepfer MS-404 MIDI bassline synthesizer, leave a comment with your thoughts.

MS-404 Features


  • real VCO (no DCO)
  • switchable between sawtooth / off / rectangle (pulse)
  • pulsewidth of rectangle adjustable, pulsewidth modulation with LFO1
  • glide time adjustable, glide on/off via MIDI-Controller #65 (Portamento)
  • frequency modulation with LFO1, even in audio range for producing typical FM sounds


  • white noise as alternative sound source (switcheable instead of VCO)


  • 24dB resonance filter (low pass), resonance/emphasis adjustable up to self oscillation
  • frequency may be controlled via any MIDI controller and/or MIDI velocity
  • frequency modulation with LFO2, even in audio range for metallic/FM sounds
  • keyboard tracking switchable off/half/full


  • envelope amount (accent) controllable via MIDI volume (ctr.#7) and/or velocity
  • effect of accent adjustable (accent knob)
  • full ADSR type (Attack-Decay-Sustain-Release)

LFO1 and LFO2

  • 3 frequency ranges from sub-LFO (some minutes oscillation period) up to audio (max. 5kHz)
  • waveform triangle
  • frequency and level adjustable
  • LFO1: to VCO frequency or VCO pulsewidth modulation switchable
  • LFO2: VCF frequency

External Audio Input

  • level adjustable
  • alternative sound source instead of VCO or Noise

MIDI-CV Interface (internal):

  • MIDI channel and transpose (reference note) selectable via learn button
  • retrigger on/off (new trigger if playing legato)
  • controlling of glide on/off via Controller #65
  • controlling of VCF frequency via any Controller and/or Velocity
  • controlling of VCA envelope amount via Controller #7 and/or velocity
  • two 1/4″ jack sockets for CV und Gate Output (may be changed to CV/Gate Input when changing jumpers inside by authorized dealers)
  • light grey 19″ housing, 1 unit


One thought on “The Doepfer MS-404 MIDI Synthesizer

  1. I have used one together with an MAQ16/3 Midi Sequencer. I disliked the single envelope. One modulation which I have used a lot is not shown in the video though, namely the Filter FM by LFO 2. It goes high into the audio range, and this is a feature not very common in compact analog synths.

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