[sdiy] help finding roland filter schematics?

[David G. Dixon]

> Have a read of Tony Oakley's COTA filter for some excellent insight and a
> great filter!
> http://www.oakleysound.co.uk/cota.htm

Thanks for the heads up, Rob!  That was very enlightening!  I guess I'm on
the right track, although I'm putting the extra gain into the 4 inbuilt
resonance amps rather than directly into the filter-block buffers.  This
way, I'll maintain the "classical" unity-gain relationships of the
filter-blocks without resonance, but still have constant-amplitude
oscillation.

It strikes me that the Oakley method of increasing the filter-block gains to
1.47 is dangerous when the cutoff frequency is turned way up.  A typical
unity-gain filter will put the incoming signal out at full strength from
each pole at very high cutoff.  This would imply that the Oakley filter will
output the signal from the 4th pole at a gain of 3.18/2 = 1.59 (given that
the first pole has a gain of 0.5).  Doesn't this imply that the outgoing
minus 24dB signal at high cutoff would be +/-8V for an incoming signal of
+/-5V?  It would also imply that the cutoff control would effective act as a
volume control at high cutoff.  Is this right?  Maybe this is desirable. (?)