In response to Dave's observations:
>I finally figured out that I was cranking the input signal (MOTM-300) too
>hot. If I back off the attenuators to 12:00, it sounds sharp and clear with
>cutting resonance. As I crank the signal more, I get some distortion, and
at
>the same time the resonance decreases. There is a gain zone where you can
>get both distortion and high resonance. Increasing the gain beyond that
adds
>more distortion, but overwhelms the resonance. Since Paul mentions on the
>web site that this design has nonconstant Q with gain, I figure that's what
>I'm seeing.
That is correct. This is the #1 "uniqueness" of a MS-20 filter. You can get
all combinations
of resonance/clipping going, as well as a "clean" sound. I use 2 '300s and
set the IN attenuators
on about 6.
>Another tip - the notch setting is most useful either at NO resonance, or
>lots of resonance. At no resonance, you get the swept notch kinda stuff. At
>high resonance, you can add a resonant peak without cutting highs or lows
>like LP or HP modes.
>
>At mid level resonance, however, you are just nullifying the notch and it
>will sound pretty close to having no filter at all.
Exactly correct again. The Notch is really best heard with 2 '420s. Also
sweping
2 Notches makes for some good phaser effects.
∗∗∗∗∗∗∗∗∗∗∗∗∗
On another note:
If you twist the IN pots with a "hot" signal (ie VCO direct output) plugged
in, you
may hear some "grunge noise" that then disappears. This is an artifact of
the
filter "bouncing" as it gets it's level rapidly swept. The pots are NOT
"bad", the filter
is mis-behaving, in a MS-20 way.
Nice to see that '420s are coming alive this weekend.
Paul S.