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

[jhaible at debitel.net]

 > > > That picture dosent tell me anything!
> >
> > The picture should tell you that Moog core clips at roughly 
> 1/4 the signal
> > level compared to OTA filter (due to OTA nonlinearities cancelling
> > better).
> > Practical meaning is that if you set up Moog & OTA filter 
> so that core
> > sees same signal level, the self oscillation amplitude is 
> 4x for OTA _and
> > therefore any clipper in feedback loop affects OTA more 
> than Moog when
> > other things are equivalent_.


I think now I understand what you mean.
"when other things are equivalent" is the important point here.

But you have so many degrees of freedom to design these filters.
Especially when you're using OTA filters with buffers and resistor
dividers, you can set your "working level" (and the clipping which
would occur in another OTA for feedback) just as you like.
And with the buffers clipping themselves, unsymmetrically as
in the 2040 even, you have that wonderful interaction of frequency
depended differential pair distortion (around the cutoff frequency,
as you explained), and the frequency independend, but somehow
transient depended, distortion from the buffers.
And you can set the operating level of a feedback OTA such that it
conztributes to the distortion, or such that it doesn't contribute
anything of importance at all.
Any colours you like.

JH.



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