35 - the next step

[tomg]

> I have further improoved the MS-20 style filter.

Yes you did. The hi-pass modification works well and the overall
performance is better. I still though there was too much clipping so I
started messing around with it and found why. The circuit doesn't oscillate
symmetrically the diode pair are there to help as much as they can but it
doesn't help much. That's why I thought the oscillation sounded different,
I'm only listening to half a sine wave. The ota version doesn't put out a
true sine eater but it is symmetrical and absolutely wonderful to listen
to.

Once I realized I wasn't going to get a better sine and abandoned  the
notion I set about getting it to sound as good as I could.  With the gain
set so high you can hardly hear the filter at work. Oh you can hear the
cutoff change but not the filter really working. I went back to 6 diodes
and a 47K in the fb loop. changed the rc resistor from 5.6K to 2.2K ,
changed the input resistors from 2.2K to 100K and the 47 ohms to 100. I
also changed the .01 hi-pass input cap to .001. 

 Pretty nice sounding, but the closer you get to oscillation the more
effect the half-sine has on the signal. At points it becomes bad and on
it's own is not that pleasing. When you get both filters beeping and
bopping on the ota version it turns into a this wonderful symphony of sine
waves warping all around. 

Juergen.... if you like this one please do the ota version you'll never
regret it. I did a AB on the bench tonight and the difference is huge.

-tg