Heavily Modded Doepfer MS404 Analog Synth with Moog 24dB Filter

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"This is a heavily modified Doepfer MS404 anlog monophonic synth, one of only two in the world. Already capable of strong bassline and leadline sounds, the mods turn this MS404 into a miniature modular system capable of some incredible sounds.

Unfortunately after being brought out of three years storage in good dry warm conditions this is no longer working. You will need a professional service to do anything useful with it, unless you intend to disassemble it for spares.

The MS404 features a single genuine analog oscillator with two waveshapes and Pulse Width Modulation, a Moog type 24dB per octave lowpass filter with full resonance, two LFO's with switchable speed ranges, ADSR and MIDI Input with Glide.

This specification makes the MS404 capable of some heavy analog bass sounds and cutting lead lines. With a similar layout to a Roland TB303 Bassline, it's not really a TB303 clone since its oscillator and filter are both much more powerful. Think more in terms of a MicroMoog in a rack.

The modifications take this MS404 to another planet. Firstly the ADSR can be bypassed so the synth drones on whatever note is played, and the VCA simply becomes a volume control. This makes the synth incredibly useful for drones and special effects sounds rather than simply bass or lead notes.

Secondly the two LFO's can both be switched from triangle to square wave - this was on the PCB as a jumper and makes a much wider variety of modulation types available.

Thirdly the output of the two LFO's can be merged so that both waveshapes reach filter and (if required) VCO. This is the killer modification, making the MS404 with its filter fully resonating sounds like the EMS VCS3 Synthi as used by Jean-Michel Jarre and by Tim Blake with Gong. Double modulation (at differing speeds) is a killer application for anyone wanting versatile analog synth abstract sound effects.

Fourthly the second LFO can repeatedly trigger the Envelope, making even more versatile effects noises and arpeggio-like patterns available.

Fifthly there's an added front panel minijack audio input to the filter making the MS404 easier to patch to a Doepfer or other modular system.

These modifications mean that this MS404 when working acts as incredible mini modular system with MIDI, in a very compact 1U 19-inch mounting.

How dead is this MS404? It powers up, so the power supply isn't burned out and there is no internal fuse to suspect. However there's currently no sound output and the LFO's appear to have stopped running. A shame, because immediately before going into storage it was sounding devastating.

You will need to be an experienced service engineer to get this working, or be willing to send it to one. You will not fix it by replacing a fuse or a loose socket. You will need someone who appreciates what the modifications are doing (they're very simple, mostly just a case of leading an existing PCB jumper out to a toggle switch).

Power cable not included (a simple IEC kettle mains lead). Knob caps not included (it had non-standard Moog-style knob caps anyway, not Doepfer system knobs). Some chassis screws missing, easily replaced.

Obviously this is sold on a no returns, absolutely no guarantees non-working basis. If fully working, it would probably fetch around £350."