Filter Terrain

A 15-band morphing filterbank where every band's gain, delay, and feedback shift continuously as you move across a 2D pad. Sweep from thin telephone tones to airy resonant shimmer to dark, warm comb-delay textures — all from two knobs. Stereo in, stereo out, with independent left/right filter and delay state.

How it works

The signal is split into 15 parallel bandpass filters with fixed centres from 50 Hz to 14 kHz. Each band feeds its own short delay line with a feedback path, so bands can ring, comb, and smear rather than just colour the tone. The sound is shaped by seven hand-authored "anchor" voices scattered across the pad — telephone, airy-bright, dark-warm, nasal, smile, scooped, and a flat rest point in the centre. Your X/Y position blends the nearest anchors by distance, so corners and edges give bold, distinct characters while the middle settles toward neutral. Moves are smoothed over about 100 ms, so even fast CV sweeps morph like liquid instead of stepping, and an auto-makeup stage keeps the level roughly even as you travel. Where X/Y navigate the terrain, three character knobs reshape what it is: Focus sets how sharp each band rings, Contrast sets how snappy the pad feels between voices, and Reso drives how hard the delay network regenerates.

Controls

  • X / Y — your position on the morph pad (horizontal and vertical). Together they choose which anchor voices blend and in what proportion; centre both for the flattest, most neutral tone and head for an edge or corner to commit to a character.
  • Mix — wet/dry blend. Fully up is all processed signal; back it off to keep the dry source present underneath the filtered colour.
  • Focus — band sharpness, the Q shared by all 15 bandpass peaks, across 0.7-16. Turn it down and the bands fatten into broad, gentle EQ-like tilts for a soft-focus morph; turn it up and they narrow into peaky, vocal, almost metallic resonators that ring and whistle as you scan. 4.32 is the neutral middle.
  • Contrast — how sharply the terrain snaps between anchor voices, from 0.1 to 0.6. Low gives tight, distinct zones with crisp transitions and plateaus of pure character; high smears the anchors together into one smooth, gradient blend. 0.25 keeps the original feel.
  • Reso — global regeneration into the per-band delay lines, 0-1.5. At 0 the delays fall silent and you're left with a dry morphing filterbank; at 1 you get the authored ringing; push toward 1.5 and the delay network combs into a metallic, resonant shimmer.

Inputs & outputs

  • In L / In R — the stereo signal to process; the two channels run the same filter shape but keep independent state, so a stereo source stays stereo.
  • X / Y / Mix / Focus / Contrast / Reso CV — voltage control over each knob, summed with the panel value. Patch LFOs or envelopes here to animate pad position, wet/dry, band sharpness, morph contrast, or delay regeneration hands-free.
  • Out L / Out R — the processed stereo result.

Tips

  • Patch two slow, slightly different LFOs into X CV and Y CV to drift endlessly across the terrain — the 100 ms smoothing keeps the journey seamless.
  • The high-feedback regions ring and comb hard; nudge Mix down there to keep dry transients punching through.
  • For evolving pads, park near a resonant corner and let tiny CV wobbles do the rest — small moves cover a lot of tonal ground.