Frap Tools CUNSA: Unconventional Filter Patching Explored

The video opens with Frap Tools’ Giovanni introducing a patch designed to push the CUNSA filter well beyond its traditional role. Rather than simply shaping harmonics, the CUNSA is treated as a playground for creative signal routing and modulation. The approach is exploratory, with an emphasis on encouraging users to think outside the box when it comes to filtering in modular setups.

From the outset, the CUNSA is not just a filter but a central hub for sonic experimentation. The patching philosophy here is about leveraging the module’s flexibility—using it as a resonant sound source, a modulator, and a processor for both audio and control voltages. This sets the tone for a session that’s as much about discovering new textures as it is about traditional filtering.

Diving into the patch, Giovanni demonstrates how stereo filtering can be achieved by routing different oscillator outputs and random voltages into multiple CUNSA channels. By patching Sapèl’s clock output into the filter’s audio input and modulating it with a Phalistri LFO, the filter is coaxed into producing liquid, resonant textures that evolve dynamically. The Q and character controls are pushed near self-oscillation, then dialed back for a more controlled response, showing how fine adjustments can yield a wide range of timbres.

Triggers are repurposed as audio signals, with clock pulses driving the filter into rhythmic, percussive territory. The demonstration includes moving signals between filter channels and using bandpass modes for spatial effects, culminating in a stereo field that’s both lively and unpredictable. This section highlights how the CUNSA can transform simple triggers and clocks into complex, evolving soundscapes.

The next phase of the patch introduces gates as modulators, with the USTA sequencer sending gate patterns to modulate the Q and character parameters of the filter. Short gates create bursts of resonance, adding rhythmic punctuation to the sound, while longer gates subtly shift the filter’s character for nuanced dynamic changes. The interplay between these gate patterns and the filter’s response demonstrates how modulation sources beyond envelopes and LFOs can yield expressive results.

LFOs are also brought into the mix, routed to the Timbre Modulation input to affect multiple parameters simultaneously. Adjustments to oscillator tuning and filter cutoff frequencies further enhance the complexity, resulting in a patch that’s both animated and intricate. The ability to fine-tune decay times and create uneven envelopes across the four filter channels showcases the CUNSA’s depth as a modulation target.

The video closes with an invitation to embrace curiosity and experimentation in filter patching. By patching bandpass outputs to separate channels on the CGM mixer, Giovanni achieves a vivid stereo image, underscoring the value of creative routing. The overall message is clear: filters like the CUNSA are not just for subtractive synthesis—they’re versatile instruments in their own right. Viewers are encouraged to try their own unconventional techniques and share ideas, keeping the spirit of modular exploration alive.