Expert Sleepers Disting NT: Spectral Conquest – FFT Mayhem in Modular

With firmware 1.14, Expert Sleepers introduces the Spectral Conquest algorithm to the Disting NT, transplanting a decade-old VST concept into the Eurorack ecosystem. The core of this algorithm is FFT-based spectral manipulation, giving modular users access to digital audio analysis and transformation typically reserved for software. The video opens with a quick patch-in and a look at the UI, which provides real-time spectrum analysis so users can see exactly how their audio is being dissected and reassembled. Adjustable FFT size and sample rate settings allow for balancing CPU load and bandwidth, though the video skips deep dives into these parameters. The focus is squarely on what spectral processing can do to incoming audio, setting the stage for a tour through a series of transformative effects.

The first stop is spectral shift, a process that moves frequency content up or down by FFT bins—distinct from pitch shifting, as it disrupts the harmonic relationships within sounds. Applied to a piano, this yields clangorous, bell-like textures, while the reverse function flips the spectrum, turning low frequencies into piercing highs. The effect is especially dramatic on drums, where bass energy is catapulted into the upper registers, resulting in unusual and sometimes abrasive timbres.

Next, the spectral gate introduces threshold-based filtering, letting only frequency bins above or below a set level pass through. This can isolate loud transients or, conversely, preserve only the quieter spectral components, offering precise control over which parts of the signal survive. The comb filter, meanwhile, uses step, width, and offset controls to carve out repeating patterns in the spectrum, producing effects reminiscent of flangers or phasers but with a distinctly digital edge. Finally, the sieve algorithms—harmonic and chordal—act as resonators, allowing users to emphasize specific harmonics or chord tones. The chord sieve even lets you blend in intervals and choose the number of octaves, resonating with particular keys or notes for targeted spectral reinforcement.

The final section covers the suite of FFT-based filters, which include low pass, high pass, band pass, and notch types. Unlike analogue filters with gradual slopes, these are described as ‘brick wall’—their frequency cutoffs are absolute, with no gentle roll-off. This precision allows for surgical removal or isolation of frequency bands, though the resolution is limited by the size of the FFT bins, which can result in a somewhat coarse effect. The video demonstrates each filter type, showing how the spectrum is sliced and manipulated in real time.

These FFT filters offer a different flavour of sound shaping compared to traditional filters, excelling at drastic spectral edits rather than subtle tone sculpting. For modular users seeking extreme frequency control or experimental processing, this approach provides a unique addition to the Disting NT’s already formidable arsenal.