Since I was away from home (and my Eurorack) for 6 months, I got a Korg re-issue ARP Odyssey to have something to play, and also to be challenged by the limitations of a fixed-architecture synth with very limited expandability. I hadn't expected such a big difference in playability, especially tweaking multiple nearby sliders with one hand.
As an exercise, I attempted to replicate the Odyssey functionality, in Eurorack. This rack mainly re-uses my existing modules (adding the minimum needed for missing functionality) rather than picking the best ones.
This exercise primarily showed my how important input attenuators and mixers are to the overall ARP Odyssey design! Most of the 2-position switches for input selection are replaced by patching, but a lot of small input attenuators and mixers are needed. Another big difference is price: €2,826 compared to €699.
VCO1 is a Dixie II got (tri core rather than saw core) which does have the famous excellent tracking and temperature stability, but misses a fixed PWM offset as well as the PWM input. Is Odyssey PWM linear or exponential? Needs a 2-input mixer for FM and 2-input mixer for PWM (offset and input). A-138n is used for FM mixing.
VCO2 is a Dixie II+ got which adds the hard sync input. Has the VCO/LFO switch. Again missing input mixers. Another A-138n is used for FM mixing.
There is also a more authentic VCO, based on the 2600 4027 VCO2, which also has a nice set of input attenuators and CV mixer.
LFO is another Dixie II got so has the sine out. A simpler LFO would be fine here.
Noise is my existing Liivatera noise module got, with white and pink outputs. Lots of other modules fine here.
Ring Mod is Doepfer A184-1 new which combines ring mod, S/H and slew. The G-Storm Electro RM&S new would be another, more authentic option (and would need a different S/H and slew module)
Waveform mixer for Ring Mod, Noise, VCO1 and VCO2 is the top half of an Erogenous Tones Levit8 got but any 4-input audio mixer would work here.
S/H is the Doepfer A184-1 which needs a 2-input mixer. The other half of the Levit8 module (which can be two 4-input mixers) is used for S/H input mixing of VCO1, VCO2, Noise.
For the three filter options (selected by patching):
- 4023 (12db, 2-pole) is G-Storm Electro 4023 VCF buy and is the most essential for the Odyssey sound
- 4035 (24db, 4-pole, moog copy) is AJH Minimod Transistor Ladder Filter new
4075 (24db, 4-pole, fixed arp design) is OIIIAudio ARP4075 Filter Clone new but the weakest of the three filer options tbh
Each filter module has mixer inputs, thankfully.
No module for "drive", not clear if needed.
Doepfer A106-6 got is the high-pass filter, but any simple HPF will do.
Intellijel Dual ADSR got is used for the ADSR and AR envelopes (AR by setting sustain level to max) , and has cycle switches plus retrig inputs.
Intellijel μVCA II got is the volume envelope VCA, with one spare.
Lastly a PulpLogic Exit Strategy got gives the balanced output for recording
A Duophonic MIDI to CV module is missing for the keyboard handling, which would also replace the PPE for pitch-bend and vibrato, and the legato slider, and perhaps the three-way octave switch. I'm working on a DIY module for that.
Comments welcome. No, I don't intend to build this, although the Doepfer A184-1 and the G-Storm Electro 4023 VCF are tempting to add to my rack.