Frap Tools Bagài: Turning Aliasing into Analogue Alchemy

Aliasing, Reimagined: The Bagài’s Analogue Approach

Aliasing is a term that usually sends shivers down the spines of digital purists, but Frap Tools’ Bagài module invites us to reconsider. In this video, Giovanni from Frap Tools sets the stage with a straightforward patch: two melodies sequenced and filtered, then introduces Bagài as the centrepiece for exploring aliasing in an all-analogue context.

Rather than treating aliasing as a flaw, Bagài harnesses it as a creative tool. The module’s design allows users to manipulate the sampling rate of incoming signals, producing quantised, unpredictable voltages and, crucially, artefacts that would be considered undesirable in a digital system. Frap Tools’ presentation style is as clear as ever, focusing on how Bagài’s quirks can be musically useful rather than simply technical oddities.

Sample & Hold: The Heart of Bagài’s Magic

At the core of Bagài lies its sample and hold circuit, which captures and freezes voltages at rates defined by an internal or external clock. This function is demonstrated by sampling both random noise and audio-rate signals, showing how the module can generate stepped voltages or even audio textures, depending on clock speed.

The flexibility of the clocking system is key. With the flip of a switch, Bagài moves from slow, modulation-rate sampling to audio-rate operation up to 32 kHz. This range enables everything from classic random modulation to the sort of down-sampled, crunchy sounds more often associated with digital bit manglers, all while remaining firmly in the analogue domain.

Downsampling & Fluctuating Random: Textures in Motion

The video dives into the sonic results of Bagài’s downsampling abilities, using fluctuating random voltages to modulate filter cutoff and create evolving timbres. As the clock rate is reduced, classic aliasing artefacts emerge, introducing a noisy, grainy edge to the sound. This is demonstrated both on noise sources and on a sine wave from the Brenso oscillator, highlighting how the module’s behaviour changes with different inputs.

By varying the clock speed and bit depth, Bagài can morph from subtle modulation source to aggressive bit crusher. The resulting textures range from tolerable digital grit at higher rates to full-on pulse wave madness when only a single bit is active. The demo makes clear that these artefacts are not just side effects, but central to Bagài’s creative potential.

"These artifacts introduced by variating the clock speed are basically aliasing."

© Screenshot/Quote: Fraptools (YouTube)

External Clocks & Bit Crushing: Expanding the Sonic Palette

"You can hear that now the aliasing effect is consistent with the pitch played by this oscillator here."

© Screenshot/Quote: Fraptools (YouTube)

Frap Tools takes the patch further by introducing external clocking, syncing Bagài’s sample and hold to the pitch of the Brenso oscillator. This alignment ensures that the aliasing artefacts track musically with the notes being played, making even the harshest digital textures feel intentional and integrated. The ability to modulate the clock source—via FM or sync—adds yet another layer of timbral complexity.

Bit crushing is also explored, with Bagài’s quantised output reducing audio signals to a handful of voltage states. The results are unpredictable and often noisy, but always musically interesting. The video wraps up by reintegrating the processed signals into the full patch, demonstrating how Bagài’s unique flavour stands apart from more conventional modulation sources. It’s a reminder that sometimes, the best sounds come from embracing the artefacts others try to avoid.