[sdiy] CEM3328 seems to only have buffers at the end

[Harry Bissell Jr]

IMHO the Moog distortion is more a product of the differential
  pair diatortion, and has very little to do with 'filter'
  
  They might be comparing the 'open loop' design with the state variable
  design.
  
  Open loop (with no resonance) would also have no Global Feedback...
  
  H^) harry

Mike <mirwin at marketbridge.ca> wrote:  Aaron & List,

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Is that what the datasheet means by "open loop design for enhanced sound
richness?" ;)
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I find this rather curious as well.... the datasheet for the SSM2045 says
something about "rich open-loop filter sound".

If you look at the typical OTA-based filters, there is (always?) a resistor
from the output buffer to the inverting input of the OTA,  which sets the
passband gain to unity, helps establish the output quiescent voltage, as
well as providing some linearizing action through negative feedback to
reduce distortion at the OTA input pair.  Each stage is independent of the
other stages. In contrast, the Moog filter and diode ladder filters do not
have this "closed-loop linearization per stage", perhaps this is part of the
reason for the different sound of the filters when they are over-driven?
Different distortion behavior as the filter is over-driven?
Mike




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