SCI Pro One Modular

Overview This is my second home built analog modular synthesizer. Back in the 1980's I had a collection of analog mono-synths, and the trusty SCI Pro One was one of the ones I loved the most. But aging pots and switches didn't make it the most playable, so I eventually sold both of the ones I had acquired.

In 2006 I started building some ARP filters in a 4U format (which was my standard at the time), using PCB's as the front panel to keep costs down. I used high quality Spectrol pots and ARP like control knobs. This was the 4075 and 4023 filters. A client requested a set of SSM2030 PCB's, so I designed these and made a couple for myself - using additional PCB's to enable push buttoning switching of waveforms - like the original Prophet 5. A CEM3320 LPF and CA3280 based VCA then followed, along with two dual ADSR's based on the CEM3310. An Oakley MIDI interface and a module containaing a CEM3340 LFO and an ARP Odyssey White/Pink Noise Source completed the set of 10 modules.

Why use rare CEM chips in Modules? Well I had quite a few lying around which I would like to use, they create some really good sounds and I don't have room for monster poly synths. In fact quite a few people have CEM chips in their stores, and some are still for sale on eBay, such as the CEM372. So let's make good use of them!

Design Details The physical design originates in my use of 4U high panels on the E-mu Modular clone, which works well with 3.5mm jack sockets and 10 - 19mm diameter control knobs. It is a non standard size, and in later synthesizers I have reverted to either 3U FracRac or 5U MOTM:

• The modules are all non-standard 4U high, 90mm wide.
• The panels are PCB material spray painted with car aryclic paint and then lettered with Transmat.
• The +/-15V power supply is Oakley Sound with Oakly Dizzy.
• The Midi to CV/Gate interface is from Oakley Souns.
• Pots are Spectrol 1/8" shaft.
• Minature "round" toggle switches and push buttons with 3mm LED's.
• Lights - 5mm LED's mounted in round plastic LED holders(Clip Lites).
• The power supply is 1.5A +/-15V and the transformer is remote.