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AM3310 - ADSR (CEM3310)
Overview The CEM3310 of 1979 was the first of a new generation of synth chips introduced by Doug Curtis. It's snappy envelopes formed the basis for many analog polyphonic synths
over the next 5 years including the Prophet 5 Rev 3, Oberheim OB8 and PPG Wave 2.0. It was eventually replaced by micro-processor created envelopes, which struggled to achieve the fast attack times of a dedicated chip until processor
speeds increased in the late 80's.
AM Circuit The AM3310 module is based on the Digisound ADSR, which is a rather more advanced implementation than that used in SCI Prophet's. It provides an automatic means of ensuring the
sustain level does not exceed the attack level, as well as output offset trim and an inverted output.
There is a manual trigger button as well as a LED for Gate On and a LED for the Attack phase. The envelope generator can be
triggered from either of 2 internal gate buses. The circuit has been carefully checked to ensure the minimum attack times are below 2ms, to get that snappy feel.
Panel Front Panel
The front panel is an AM High Density design, 90mm wide, 3mm thick aluminium, 4U high, with black lettering. Controls pots are 3.85mm diameter, knobs are 13mm in diameter - black and chrome. Switches are sub-minature toggles and panel mounted 3mm LED's are used throughout. There is a CV signal monitor for each channel with a 10 LED bar graph.
Build History The schematic has been transferred into Eagle CAD, and the board layout needs to be completed.
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Resources
* CEM3310 Datasheet 
* AM3310 Project Notes