k2k audio sound-design
Projects
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k2k is a node-based spectral audio explorer and polyrhythmic sequencer in one application.
Editor mode — load audio, build processing chains with a visual node graph, and see the results through four scopes: waveform, spectrum, spectrogram, and 3D spectral terrain. Eighteen color modes act as different lenses on the same sound — amplitude, harmonics, transients, phase behavior, formants, and more. What you see, you can extract with nodes, process, morph, and recombine.
Player mode — an 8-track polyrhythmic sequencer where every track runs independently. Different pattern lengths, different time divisions, per-substep parameter control, Euclidean pattern generation. Sounds processed in the Editor flow into the Player’s sample bank.
The two modes connect through a shared workflow: dissect and transform audio in the Editor, perform and compose with it in the Player.
k2k runs standalone on Linux, macOS, and Windows, with a VST bridge for DAW integration (8 audio tracks, bidirectional MIDI/OSC).
Status: Late alpha. Available to Patreon supporters.
Documentation
- Editor — graph-based spectral sample prep. Reference (scopes, color modes, modulation), every node by category.
- Player — polyrhythmic step sequencer. Reference (panels, scopes, parameter contexts, grid automation).
Documentation
- Multi-Tap Delay
MultiTap Delay produces multiple delayed copies of the input, with each "tap" having its own delay time, level, and stereo position. - BitCrusher
Bit Crusher is the lo-fi destruction node — pairs bit_depth reduction (quantization staircase) with rate_factor sample-rate reduction (downsampling aliasing)… - Compressor (Native)
Native Compressor is K2K's full-featured dynamics processor — threshold/ratio/attack/release/knee/makeup with sidechain HPF, peak/RMS detection, and four… - Multimode Filter
Most modern multimode filters offer a choice of "circuit" — different ways to arrange the same basic filter math, each with subtly (or dramatically) different… - Spectral Mod Delay
Spectral Mod Delay is the spectral-domain cousin of the regular Mod Delay. - Pitch Shift
Pitch Shift is K2K's main phase-vocoder pitch shifter — preserves duration, shifts pitch, with quality/latency trade-off via fft_size. - Reverb (Native)
Native Reverb is K2K's algorithmic reverb workhorse — a tunable space modeler with separate controls for size, damping, predelay, width, early reflections… - Spatial Lab
Spatial Lab is the workhorse mono → stereo positioner: pan with three classic laws, optional M/S width, optional Doppler for moving sources. - Smooth
Smooth applies a Gaussian blur to the spectral magnitude — the inverse operation of Sharpen. - Time Reverse
Reversing audio is normally a time-domain operation: play the samples backward. - Matrix Delay
Matrix Delay is a 4-delay-line FDN (feedback delay network) with a 4×4 gain matrix that controls how each line feeds into the others. - Wavefolder
Wavefolding comes from West Coast synthesis (Buchla, Serge), where it's a primary tone-shaping element instead of a distortion afterthought. - Limiter (Native)
A limiter is essentially a compressor with infinite ratio and a fast attack — anything that tries to exceed the ceiling gets clamped down hard. - Comb Resonator
A comb filter is a delay line fed back on itself — short delays create resonant tones at their reciprocal frequency (a 2.27 ms delay resonates at 440 Hz). - Mod Delay
Mod Delay is a short-delay-line modulation effect. - Harmonizer
Harmonizer stacks 2–4 pitch-shifted copies of the input on top of itself for harmony generation — set intervals via the multi-point widget, balance each voice… - Dattorro Plate Reverb
The Dattorro plate reverb (designed by Jon Dattorro and published in his classic 1997 paper) is one of the most musical algorithmic reverbs ever designed. - Spatial Mix
Spatial Mix places two mono sources independently in a stereo scene with a shared distance model. - Sharpen
Sharpen applies a Laplacian convolution kernel (the same image-processing filter used to enhance edges in photos) to the spectral magnitude. - Time Crop
Time Crop extracts a specific time region from the input ComplexBuffer, optionally with fades at the boundaries. - Delay
Echoes and rhythmic repeats. - Delay (Native)
Native Delay is K2K's full-featured stereo delay — two delay lines (L/R), independent or synced, with feedback, filtering inside the feedback path, stereo… - Harmonic Shaper
K2K's Harmonic Shaper uses Chebyshev polynomials, which let each h-knob control the amplitude of one specific harmonic with surgical precision — h2 controls… - Gate (Native)
Native Gate is the inverse of the compressor — silences (or attenuates) signal below threshold rather than clamping signal above it. - Parametric EQ
The Parametric EQ exposes 4 bands: a low shelf, two parametric (peaking) bands, and a high shelf. - Frequency Shifter
Pitch shifting (semitones) preserves musical intervals — a chord stays a chord, harmonics stay harmonic. - Shimmer Reverb
Shimmer reverb (popularized by the Eventide H8000 and similar units, used heavily on cinematic strings, ambient guitars, and worship music) is a reverb where… - Dynamic Brightness
This node uses Harmonic-Percussive Source Separation (HPSS) to split the input into three streams — harmonic (sustained pitched content), percussive… - Time Concat
Time Concat joins two ComplexBuffers in sequence — Input A first, then Input B. - Distortion
From gentle warmth to controlled destruction. - Soft Clipper (Native)
Native Soft Clipper is the lightest member of the distortion family — peak management first, harmonic coloration second. - Expander (Native)
Expansion is the gentler cousin of gating. - Envelope Resonator
An envelope resonator is a resonator (like the Comb Resonator) whose ring is gated by the input level. - Leslie
The Leslie speaker cabinet (originally designed by Don Leslie in the 1940s) was the iconic partner to the Hammond B3 organ. - Spring Reverb
Spring reverb is a vintage reverb technology where audio drives a transducer at one end of a metal spring, and a pickup at the other end captures the signal as… - Spectral Saturation
Time-domain saturation (the kind in the Saturator and SoftClipper nodes in the Distortion category) works by waveshaping — bending the waveform to generate… - Time Warp
Time Warp is non-linear time-stretching. - Saturator (Native)
Native Saturator is the color-focused middle ground of the distortion family — sits between Native Soft Clipper (peak management with mild coloring) and Native… - Dynamics
Volume control with a brain. - Spectral Compressor
Spectral dynamics nodes are unique to K2K's domain: they operate on the spectral data directly, frame-by-frame, with independent control over each frequency… - Monophonic Noise Filter
This node assumes the input is monophonic — a single voice, a single solo instrument — and uses pitch detection to identify which spectral content belongs to… - Phaser (Native)
A phaser passes the audio through a chain of allpass filters whose center frequencies are modulated by an LFO. - Convolution Reverb
Convolution reverb works by recording the impulse response (IR) of a real space (or a piece of gear), then mathematically applying that IR to your audio — the… - Spectral Roughness
Digital signals are mathematically smooth — every bin is exactly what the algorithm calculated. - Frame Hold
Frame Hold is sample-and-hold for the spectral domain. - Distortion (Native)
Native Distortion is the heaviest of K2K's harmonic-distortion family — designed for full amp-style aggression rather than the gentler coloring of saturation… - Spectral Expander
A spectral expander pushes down quiet frequencies per frame, rather than pushing down quiet moments. - Adaptive Notch
A regular notch filter sits at a fixed frequency. - Spectral Dither
In its traditional form, dither is a tiny amount of noise added during bit-depth reduction to mask quantization distortion. - Spectral Smear
Spectral Smear is "motion blur for audio" — where motion blur in video averages adjacent video frames to convey movement, this averages adjacent spectral… - Spectral Gate
Spectral gating reduces noise band-by-band rather than time-by-time. - Filter
Sculpting the spectrum. - Spectral Erosion
Spectral Erosion is named for the visual analogy: like rocks worn smooth by water or paint flaking off an old wall, this node "wears away" at the spectrum… - Spectral Echo
Spectral Echo generates a fixed number of decaying repeats at equal time intervals — closer to a tape echo or simple delay-line effect, but operating… - Spectral Ducker — Per-frequency-band sidechain ducking
Ducking pulls one signal's level down in response to another. - Spectral Stutter
Spectral Stutter is rhythmic capture-and-replay in the spectral domain. - Spectral Limiter — Per-frequency-band brickwall limiter
A spectral limiter clamps peaks per frequency band rather than across the whole signal. - Modulation
Movement and motion. - Time Quantize
Time Quantize is a creative spectral-domain quantizer with three strategies. - Spectral Transient Shaper
Most transient shapers are broadband: they detect transients across the whole signal and boost or cut them globally. - Spectral Freeze Stutter
This node combines two ideas: freeze (spectral hold of a single moment, like a held capture) and stutter (rhythmic repetition triggered by an LFO). - Spectral Gating
Cross-spectral gating uses one signal's spectrum to control another's. - Spectral Delay
A spectral delay applies a different delay time per frequency bin — unlike a normal delay where all frequencies arrive at the echo together, a spectral delay… - Pitch
Re-tuning, re-voicing, harmonising. - Grain Cloud
Grain Cloud is K2K's flagship granular synthesis node — the source's audio is chopped into short windowed grains and re-fired into a continuous cloud, with… - Paulstretch
Paulstretch is a specific algorithm (named after its creator Nasca Octavian Paul) designed for extreme time-stretching. - Reverb
The shape of a room, captured in code. - Spatial
Where the sound sits. - Nodes
Reference for all 103 nodes in the k2k Editor — spectral analysis, distortion, dynamics, filter, time, texture, extractors, masks, and more.