The device is presented as a “sample/hold filter,” but that soundbite can be confusing. This ain’t no audio sampler nor a looper, but – to quote Wikipedia – it utilizes an analog circuit to “sample (capture, take) the voltage of a continuously varying analog signal and hold (lock, freeze) its value at a constant level for a specified minimum period of time.”
This kind of circuit was used in filters on some vintage synths and adopted in other filter pedals like the Subdecay Proteus, ZVex Ooh Wah, and Xotic Robotalk.
So yes, the Psychotropia is a Filter pedal, and a rather unusual one that continues Yellowcake’s interest in creative stompboxes inaugurated by the 2018 release of the Lida Machine.
The Psychotropia is at its heart a tap-tampo enabled autowah-style filter using “weirder” LFO waves, controllable Resonance and an a series of controls that allow to modify the resulting LFO shape and EQ. CV In/Outs make it compatible with synths supporting that format (read: Eurorack).
The shape of the LFO can be set to three different waves that are way more complex than your regular autowah sine wave, featuring an assortment of sweeps and steps; they can be changed through the left toggle (see minute 2.07 in the video below). The “angularity” of the steps can be tamed by raising the value of the Glide knob. The Hi/Low toggle switch gives you a brighter and darker tone option, while the Log/Lin one makes the edges of the square waves, respectively, harder or softer.
Check out what you can do with this pedal on Eric Merrow’s video below!
A sample/hold filter with a glide knob option that that interacts with a toggle switch for rising and falling wave forms.A lin/log toggle switch, where the ‘lin’ is a hard edge square wave and the ‘lin’ position softens the edges of the square wave pattern.
Other features are hi/low eq cut, tap tempo to adjust rate on the fly instead using the rate knob, a ‘res’ or resonance knob for feedback oscillation and cv in and cv out.