Do i spot a moog drummachine????

[CZ Rider]

Unbelievable!
This just showed up today on the BMF site.
Bob's schematic drawing of the #1 board VCO/CVF/VCA of the 701.

And there it is! Well half of it. My guesses were close, three saw core VCO's, a two pole LPF and VCA.
And my guess was spot on that the BMF has these schematics they should be sharing with the synth community. AFAIK this is the first time these drawings of the 701 have been shown to the public.
I still want to see the drawings for the Red Noise Filter.
I am currently cloning the 901C and wanted to add the "Modulation Mix" pan pot the Minimoog has for added function. I have the schematic to filter the 903 white noise to pink, but I have to guess on the red noise filter. A drawing from Bob would make it so much easier and correct.

[CZ Rider]

They posted another drawing. Had to study it a little, very low resolution pic of the drawing. Looks to be the component layout on the second 701 board with the envelopes.
(Drawing below with pic of the board I pasted above.)


I'm finding this newly released info very interesting. I could almost make a 701 clone from these bits of info. I like the way Bob drew the components out for the Plugbaord. Never saw these kind of drawings from Bob before. A higher resolution scan of all the pages/notes Bob kept would be all that is needed. I'm sure Bob kept similar type notes for all these early modules.

Somewhere out there is all this missing info on these and other unique modules Bob designed. Like the 901D Variable Output Stage. Probably a hand drawn set just like the 701 drum module, with schematic and layout. Then there is the 902-A Band Pass Filter Adapter, 906 Impulse Generator, 913 Triggered Envelope Generator, and that 702 percussion module.
Would be fun to have a look at these!

[EricK]

You sound excited, CZ.

Are these patented or public domain or what?

[CZ Rider]

The 701 is an old prototype design from 1969. Some of those parts are hard to source, a few transistors and those CL-1 diodes.
Just seems funny for all these years the 701 and 702 modules were one of those Moog mysteries. No one really knew anything about them, other than they were used for the historic "Jazz in the Garden" concert. And a custom system was sold to Eric Siday. Most recently Tomto posted the first ever demo of a working 701, and some photos of the circuit boards. And now the actual schematic/drawings Bob drew out appear?
Anyhow this was probably the first ever synthesized drum/percussion modules ever made. Doubt there was ever any patent applied for. The 702 is still a mystery. With the "excitation" section using "repition" and "regularity" knobs, one can only guess what this did. For drum rolls?
But I am fascinated with those early transistor designes Bob came up with, and that Vectorboard they used, very 60's. Have been trying some of my own. Here is the 901C board with room for the pink and red noise filter. Using that same method of Vectorboard with the little pins and 22 pin edge card. A Moog S-trig to V-trig converter below.


It would be fun to make some of those 701 drum modules.