In other words, can I plug my guitar into the Slim Phatty’s audio in and process the signal like I would with a moogerfooger?
I would like process my guitar signal while controlling the SP with my MP-201.
Yes, you can. Anything plugged into the Audio In on the LP goes through the filter and the amplifier – so anything you do to filter or volume parameters will have an effect on the sound. That opens up a fair number of possibilities: you can do anything you could do with an MF-101 pedal, plus additional filter effects because of the filter envelope, and also amplitude modulation and gating effects using the Gate CV input and/or the Volume CV input and/or the onboard volume envelope.
Except no envelope follower, or expression pedal input for anything except for Filter Cutoff and basic Volume.
This may or may not be important to you but if playing a guitar, you might want the “auto” wah sound and the Envelope follower of the MF-101 tracks amplitude wo when you play harder, the envelope opens more and you can control the waveform somewhat.
On the other hand, the SP run an LFO to control the rate and waveform at which the Filter envelope is open/closed and you can SYNC to Midi if that is important to you. If you wanted to do this with MF’s directly, you’d need either another LFO source or a MP-201/CP-251 to drive it.
For what it’s worth, the MF-107 has an envelope follower also but it’s somewhat different than the one within the MF-101. If you ONLY have the 107, you could send the ENV follower into the SP’s Filter EXP input, but wouldn’t have control over Resonance or other CV inputs unless you had an external box or pedal to send Midi CC data to the LP.