[sdiy] You all missed my arp omni chronicles..

[Bob Weigel]

Oh my..what a basket case.  Several 4069 chips were bad.  Connectors had 
been stuck on wrong and even pins reversed in interconnects.  One caused 
a transistor to decay then burn out for the sustain voltage ref.  That 
was our final treat last night. But

1) I swapped in an op amp for the AD envelope buffer...figured I'd 
upgrade the 1458 since I saw no reason not.  Put in the 4560.  Now my 
attack was fine...but as soon as the attack reached the voltage rail 
WONK!  Sound dies.  After scratching my head a bit I finally got around 
to scoping both the output AND the capacitor charging on the other side 
of the buffer amp.  The cap did exactly what it was supposed to do...the 
amp output....did exactly what I was hearing!  A guy in AH suggested 
that there are some op amps which actually in a buffer ap will invert 
the output when you hit rail!  I had already tried a 4558 also and this 
was the case.  The 1458 is the only amp that works in that particular 
type of applications of the three!  Nice...to know that! :)

2) There is a remaining strange problem.  The synth bass if you release 
before it's envelope runs the course, triggers the low C on release in 
place of the note that should continue to decay.  The String bass and 
cello both do it no matter what.  All the envelopes and everything work 
fine and consistent now.  Quite strange. 

-Bob