[sdiy] Figureing out Buchla timbre waveshaper

[Peter Grenader]

Another diff, the Easel VCO uses the infamous 726 heated tranny pair.  The
259 used the (also extinct) AD811.  And although he spec'd the 726 in the
Easel as he did in the original 258, he abandoned the 258's servo drive for
(the push pull) and introduced the drive which would also be used in the
259, sans, the gain trimmer.

More evidence of the Easel VCO being the missing link of sorts between the
258 and 259 -- you'll notice the Easel still used the discrete (tranny)
comparator  the 258 did for the reset.  On the 259 he got smart and stuck a
311 in there instead.

If I remember correctly, there are also some caps in parallel on the Easel
somewhere.  A true Don-ism. Hey, some chefs cook by feel, some stick to
recipes.  You'll never find anyone willing to accuse Buchla of being
boilerplate, or a textbook electronics design engineer, either.  He bends a
lot of rules and his circuits are full of band aids.   Who in their right
mind would design a VCA using the world's slowest-reacting component - the
vactrol?    But hey  -the shit sounds great!

He was a Physics major at Stanford, not an EE.

- P