It might be a matter of personal preference, but for me, adding the 251 to any mf (although I don’t yet own/haven’t tried a MuRF) made them like a whole new module to me.
For example… start with a 101. By itself, its a great module that you can use as a static filter, as a manually manipulated filter (ie., you turn the knob with your fingers), as a sine wave generator, as a envelope to cv convertor, as an envelope follower hard-wired to the filter’s frequency cutoff. You can go a little further by adding an expression pedal (a variation on the manually manipulated filter or as a volume pedal) and by just patching stuff on the back of the pedal (I haven’t found a whole lot of useful stuff here - anybody?).
Now add a 251.
You can now modulate the 101’s frequency, resonance, or mix:
-with noise
-with a triangle lfo
-with a square lfo
-with either of the above shaped with the lag
-with noise sampled s/h
-with smooth noise sampled s/h
-with the output of the 101’s envelope follower attenuated or offset
-with the output of the envelope follower as the source for the s/h
-with either shape lfo or the s/h with the lfo rate modulated by the env follower
or a combination of these, using the mixer.
With a 101 and two 251’s you can get into even more complex modulation:
-combining multiple lfo’s
-using one lfo to modulate the rate of the other
-using the second lfo as the source for the s/h - this one is particularly cool, as it sets up strange scales and apreggios in the result
-cross modulation of the s/h’s (I’ll let you work our the possible permutations there!)
also - with expression pedals - a 251 is excellent for tuning the pedal to the effect you want it to have on the mf, mostly with attenuation/offset and lag. and using an expression pedal as a source for the s/h is pretty interesting:)
you can use an expression pedal to control the rate of the lfo - even push it beyond the frequency that turning the know all the way up will get you!
this is not to say the a 101 and 102 are not a formidible pair - allowing you to do stuff like env followed ring mods, routing the 102’s lfo to the 101 and so on - there’s a similarly long list of amazing things these two together will do as well.
but to me, for a new user, picking up a 251 instead of a second mf right away:
1 is less expensive
2 goes farther teaching you about how CV works and what you can do with it
3 helps you explore the limits of what your mf can do and get the the most out of it
5 when you eventually get that second mf, you’ll already have 251 you can explore it with and make you want another 251
if anyone feels like talking moogerfoogers and related stuff - i’m usually on IM - s16016wb is my screenname
Will 