
Update via Sneak Thief in the comments:
"It sounds good because the ASM-2, synthesizers.com & several CGS modules are based on a series of DIY plans released in the early 70's electronics publication called Electronotes: http://electronotes.netfirms.com/
In 1975 the authors of Electronotes, Bernie Hutchins, wrote a book called the "Musical Engineer's Handbook" - both the Electronotes series and this book have basically been the reference and inspiration for a good portion of todays modular synths.
In fact, Don Buchla, Bob Moog and Serge Tcherepnin were all subscribers to Electronotes and were definitely inspired by the schematics, and even contributed their own to the magazine.
I would even go so far to say that almost every current modular manufacturer has "borrowed" designs from the Electronotes series ; )"