VSL VCO-81 Prototype

Published on May 7, 2019 Vintage Synthlab

Playlist:

1. VSL VCO-81 prototype (x3 voices) with SYNC and FM interaction CEM3340 analog

VCO-81 prototypes with brief SYNC modes and FM explored.

2. VSL VCO-81 Eurorack 12hp precision analog VCO CEM3340 4-voice unison tracking demo

Here we have 4 of our VCO-81 prototypes sharing the same CV (1v/oct) source, acting as one quad VCO voice in unison. Tracking for our design is the most accurate and linear response of any CEM3340 on the synthesizer marketplace as of today. Pricing and availability TBA soon.

CEM Filter demo

CEM Filter demo from Bill Felton on Vimeo.

"This is a quickie demo of the Modcan CEM Low Pass Filter, model 29A. The video was shot under bad lighting conditions that QuickTime had trouble compensating for. Sorry about the image quality, but it is, after all, more about the sound ;-)
Dual VDO provides the input sound, cutoff, resonance, vc of resonance and self-resonance, and the difference between 0 and -12dB modes are shown/heard.
Primarily intended for the audience at Muff Wiggler forum."

1980 CEM Ad

via Retro Synth Ads where you'll find the write-up.

"Curtis Electromusic Specialties "What a Difference a Chip Makes" 1/4-page advertisement on page 71 in Contemporary Keyboard February 1980.

This rare advertisement only seems to have found its way into CK a couple of times. But ain't it the truth: what a difference a chip *does* make."

CEM3360 CURTIS ANALOG Filter and CEM3340 VCO Chips

via this auction

You can see what synths these were used on Synthesis Technology/MOTM's CEM & SSM page.

Update via Qwave in the comments: "MIssing Curtis/SSM chips in Waldorf synths on the Synthesis Technology/MOTM's CEM & SSM page:

MW I (Rev A):
8x Curtis CEM 3389 Filter
4x Curtis CEM 5508H Octal Sample & Hold

MW I (Rev B):
8x Curtis CEM 3387 Filter
4x Curtis CEM 5508H Octal Sample & Hold

waveSlave:
8x Curtis CEM 3389 Filter
4x Curtis CEM 5508H Octal Sample & Hold

WAVE:
16x Curtis CEM 3389 Filter
16x Curtis CEM 5508H Octal Sample & Hold
16 x SSM 2024 Quad current controlled Class A amplifier with S/N > 82dB

4-Pole (12V version):
1x Curtis CEM 3387 Filter"

CEM3394 DIY SYNTH MFOS 16 STEP SEQUENCER

YouTube via nicotinetech
"This video is to desmonstrate the possibility of the Curtis cem3394 ( video games board recycled chip)."

Pictures of dead CEM chips

"It has long been known that the CEM chips used in so many synthesizers were semi-custom IC. Doug Curtis, just out of college, had won a design contest sponsored by Interdesign (later sold to Ferranti/GEC Plessey) and went on to work for Interdesign before founding Curtis Electromusic Specialties, later to fold into OnChip Systems. The founder of Interdesign and designer of the '555 timer chip, Hans Camenzind, still operates consultancy business in mask programmable analog semicustom IC, Array Design and has written the book Designing Analog Chips that is available free for download or as a print-on-demand hardcopy.

Here are the first two pictures of de-encapsulated (defect) CEM chips, more to follow as time permits."
CEM3340/CEM3345 on top
CEM3310 on bottom
You can find more including the data sheets on Stromeko: DIY Stuff.

CEM5530

via this auction
"CEM5530 Synth Part,30 channel Sample and Hold multiplexer. These are extremely rare I.C.'s. This is a new part,(not used or pulled from a synth). This part is found in the Prophet VS,Studio 440,Keytek etc... I have other CEM ans SSM parts available as well."
You can find a pdf for the chip on MOTM's CEM chip page.