You certainly can.
Not sure if you want to repeatedly trigger the envelope according to a drum beat (which is a bit more tricky), have the LFO drive the filter cutoff at a given rate, or just use the filter to shape the incoming audio signal but here’s a quick overview.
As an effect, you can certainly use a standard Insert cable from your mixing desk into the Audio-in (the tip), returning from the Minitaur audio out. Of if you have a direct out or effect loop on your board, you might be better served having the Minitaur output on it’s own channel, then just dial up the effect on the audio channel you want to process.
In either case, you need to be aware that there is a ‘hidden’ under-the-hood setting that controls the “EXT AUDIO IN” and it should be set to 50% by default. You will need the Minitaur Editor in order to confirm this, or you can set the level with Midi CC (see manual).
Otherwise:
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Open and keep open the gate, unless you are driving it through the KB GATE input. You can do this with a shorted cable in the KB GATE jack; a footswitch that offers either ‘latch’ or polarity that can be set the ‘wrong’ way; or put something heavy across some of the black keys on your Midi keyboard.
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You will want to have the VCOs in Minitaur OFF (unless you want a drone at a certain note) so set both VCO # LVL controls CCW/Anticlockwise.
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Play whatever audio you desire and move the Cutoff knob and RES knobs accordingly.
Remember, if you are holding the gate open (as described above), you will need to remember that the envelope will ONLY trigger once according to the settings in the ENV section. So set the ENV “SUSTAIN” knob and the VCA SUSTAIN fully clockwise so that it does not decay until closed (else no sound will come out).
LFO Rate and VCF LFO AMT is always handy, especially if you can sync your Minitaur to Midi Clock (independent of firing the envelope via snare hit).
I hope this helps. If I missed a step, somebody please pitch in.
But to address your notion of using and Audio track to ‘control’ the Filter cutoff (I think you were trying to suggest something along these lines), one thing to know is that Audio signals, while ‘voltage’ across the wire, are not normally in range of what a CV control will be able to do anything useful with. If this is your desire, you’ll need a device with an amplitude envelope follower if you wish to control one of the CV jacks based on the loudness of an audio signal, or a whole other set of gear if you are thinking of somehow tracking the pitch of a frequency and producing a signal that is higher in voltage as the frequency of a signal rises.
There is plenty you can do with the simple method above, and if interested in integrating to a DAW, have a look at the Expert Sleeper products which bridge, to a great extent, the audio, Midi control and CV worlds.