X-Series Dual EG

Envelope Generator / VCA

Crucial to the filtering and final output of any synthesizer are the Envelope Generators. There are various types of EGs in different designs and some are simple, some more complex. The X-Series Dual EG is a classic ADS design. Using totally dicrete parts- the switch on time for this module can be very fast! I designed the X-Series Dual EG to have three ranges of operation- Fast (which is well 'snappy') Medium, which very typical of most vintage analogue synths and Slow- which is great for long drawn out rise and fall times- perfect for Ambient Music. As the name suggests- this is a dual envelope generator- typically, one would use the first EG to control the cutoff frequency of a voltage controlled filter and the second EG to control the output or volume of a VCA. I thought that it would be an important addition to include a built in utility VCA for that final output. The VCA, like most of the circuitry in this module, is a discrete transistor based design that adds extra clarity to the final output.

https://web.archive.org/web/20140525023202fw_/http://www.macbethstudiosystems.com/3udualeg.html