[sdiy] Ladder filter pole

[Gene Stopp]

Thanks, Tim!

Yup it's a Moog ladder allright... I wonder if the LF353 dual buffer is
*really* needed before the two 3080's at the audio output. Would parallel
3080's load down the final stage that much? One for output, one for VC
resonance. Also the expo converter is VCO-quality with a tempco and
everything. Seems like typical late-70's Moog engineering overkill to me (a
la polymoog)... guess it made sense at the time in a polyphonic machine.

One thing that bugs me about CEM-based poly machines is that they sometimes
sound "too perfect", almost to the point of sounding actually thin. It was
as if the goal at the time was as close to repeatable perfection as
possible, what with the looming threat of the digitals on the horizon. So
lots of conservative design, lots of trimpots, and matched everything. The
problem was that they could get close, but never perfect, and the perfect
repeatability of the digitals meant you could deeply FM or ring modulate one
thing with another and get the same thing every time you called it up. This
was their big advantage, since anything that was ultimately analog could
never get this kind of perfection. When your modulation depths and
frequencies are so large, you only need to be off by part of a waveform
phase and your repeatability is lost.

The bright side of this is now that these hybrid dinosaurs are 20 years old,
they've all drifted and are out of calibration so they sound better than
ever (as long as you don't try to make piano sounds). Like an Oberheim
8-voice SEM system without the programmer.

Best Regards,

- Gene


-----Original Message-----
From: Tim Ressel [mailto:madhun2001 at yahoo.com]
Sent: Wednesday, April 17, 2002 5:09 PM
To: Gene Stopp; Synth-DIY
Subject: RE: [sdiy] Ladder filter pole


Here is a site for memorymoog filter schizmoos:

http://www.retrosynth.com/docs/memorymoog/index.html

--TR