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AM Odyssey 500 - Analog Monosynth
Project Status at 11/2004 Some of the circuits have been transferred into Eagle CAD, and most of the unusual parts have been located. All PCB's should be prototyped by Easter 2005,
and production CAD files should be ready in mid 2005.
Introduction The ARP Odyssey is a classic analog synhesizer, with a great sound and a unique design. However 30 years on it has some weaknesses. There is no MIDI, the
keyboard is hopeless and the VCA is really noisy. The sliders are stiff and irreplaceble. I bought my Mark 3 model in 1985 and I loved its sound, but hated its downsides. So rather than modernise it I sold it in 2003 to the UK's leading
Gary Numan "replica" band and started work on the ultimate Odyssey - the Model 500.
Overview
The Model 500 is an enhanced replica of the original but with some new features to make it look and sound amazing! The Model 500 I am building is a closed design just like the original but without a keyboard, not a modular design with external signal and audio inputs for each module. However you could build the circuit blocks into a modular synth, if you wish.
The original Odyssey circuits are being replicated and slightly upgraded, then transferred to modern PCB's. The CAD files will be available as free downloads on this web page, so anyone can build a Model 500 by sending the files to
a prototype PCB manufacturer, and then populating the boards with parts and wiring them into the control panel. See the Project Notes on the right for details.
Key Features The Model 500 is built into a 4U high 19" wide rack
with a wooden cabinet, and has the following features:
- There 6 are circuit blocks:
- VCO1 and Ring Modulation
- VCO2
- Modulation (S&H, Noise, LFO)
- VCF (choice of 3)
- ADSR
- High Pass Filter, VCA and AR
- The VCO's from the Mark 3 are stable and work well - they are easy to replicate and are the basis for the Model 500.
- There are 3 low pass filters that can be used with the Model 500:
- ARP 4023 (12dB LPF - Odyssey Mk1)
- ARP 4012 (24dB Moog LPF - ARP 2600)
- ARP 4075 (24dB ARP LPF - Odyssey Mk3)
- The high pass filter, LFO, Noise and S&H are retained.
- The LFO has a "run free" option
- The ADSR and AR envelopes are a tad slow with 5ms attack times, but they are retained unchanged.
- The CA3080 based VCA is really noisy, so it is replaced with a low noise THAT2180 design.
- MIDI with aftertouch, velocity and modulation busses will be fitted if there is space
- The sliders have been replaced with rotary pots, high quality Bourns models with small 3.18mm shafts so we can keep the packing density high.
- Knobs are small, black and silver.
- Slider switches are high quality sub minatures
- The panel colour scheme will be light blue with white lettering. A complete change to the previous Odysseys
- Integral high quality power supply
- Everything is housed in a wooden cabinet
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