Eurorack Reference / modules /4ms/spectral-multiband-resonator audit site v0.1 — milestone 3
4ms/spectral-multiband-resonator

Spectral Multiband Resonator

4ms

Six-channel resonant bandpass filter bank with variable Q, quantized scales, rotation/spread, stereo I/O, envelope/trigger/1V/oct outputs per channel, and extensive CV control.163

Capabilities 4

Envelope Followerenvelope-follower
Six per-band Env Out jacks follow frequency content of corresponding filter channel. Fast/Slow/Trigger modes available. Pre/Post switch selects pre- or post-fader signal.163
Filter Bankfilter-bank
Six variable-Q bandpass resonators with quantized scale frequencies. Channels are spread across stereo even/odd channels. Frequencies quantized to 20-note scales across multiple tuning systems.163
Sequencersequencer
In v5+, Env Out jacks output 1V/oct CV across 8 octaves (C1–C9) when ROTATE is held while switching to Fast. Rotation, Spread, Scale, Transposition, and Freq Nudge all update the 1V/oct outputs. Glissando via Pre/Post switch + Morph.163
Vocodervocoder
Two SMRs used together: first SMR's Env Out jacks (set to envelope mode, Post) patched to second SMR's Level CV jacks, transferring spectral envelope from modulator to carrier signal.163

Jacks 16 — 13 in / 3 out

NameSignalVoltageDescription
Inputs (13)
Evens INaudio163
Freq jack (Evens)cv0V to 10V163
Freq jack (Odds)cv0V to 10V163
Level CV 1-6cv0V to 5V163
Lock jack (Odds)trigger≥2V163
Morph CVcv0V to 10V163
Odds INaudio163
Res (Q) CVcv0V to 5V163
Rotate CCW Trigtrigger≥2V163
Rotate CVcv0V to 5V163
Rotate CW Trigtrigger≥2V163
Scale CVcv0V to 5V163
Spread CVcv0V to 10V163
Outputs (3)
Env Out 1-6mixed0V to 8V163
Evens OUTaudio163
Odds OUTaudio163

Parameters 16

NameTypeRangeBehavior
135|1 SwitchswitchSelects whether the Freq jack, Freq Nudge knob, and Lock jack on the odd side control all odd channels (1,3,5) or only channel 1.163
246|6 SwitchswitchSelects whether the Freq jack, Freq Nudge knob, and Lock jack on the even side control all even channels (2,4,6) or only channel 6.163
CV Slew SwitchswitchWhen flipped on, applies slew-limiting to all Level CV jacks to prevent clicks from gates/triggers. The amount of slewing is set by the Morph knob position at the moment the switch is engaged.163
Fast|Slow SwitchswitchThree-way switch: Fast (left) = fast envelope CV tracking; center = trigger mode; Slow (right) = slow/averaged envelope CV. In v5, holding ROTATE while flipping to Fast enables 1V/oct output mode on Env Out jacks.163
Freq Nudge (Evens)knob0% – 100%163
Freq Nudge (Odds)knob0% – 100%Fine-tunes the frequency of odd channels (1,3,5) or just channel 1, depending on the 135|1 switch. At 100%, shifts frequency up ~120 cents (just over a semitone). In v5, works exponentially for precise cent tuning. Also used for transposition when held with a Lock button (±6 semitones).163
Level Sliders 1-6faderSets the output level for each filter channel. Also attenuates the Level CV input for that channel. In trigger mode (Env Out), sets the threshold at which triggers fire when Pre/Post is set to Post. LEDs show level and optionally clipping.163
Lock Buttons 1-6buttonLocks the frequency of a channel, preventing rotation, spread, scale/bank changes, and Freq Nudge from affecting it. Holding the Lock button while turning RES(Q) enables Q-lock. Also used for Transposition entry, Forbidden Note entry, and settings save/recall.163
Morphknob0% – 100%Sets the cross-fade duration when channels are rotated, spread, or scale is changed. At minimum, cross-fade is nearly instant (a few microseconds); at maximum, one second per step (full ring rotation ~20 seconds). Also sets glissando time for 1V/oct outputs and slew amount for CV Slew switch.163
Pre|Post SwitchswitchIn envelope mode: Pre = Env Out responds to raw audio input, ignoring sliders; Post = Env Out responds to signal after slider attenuation. In trigger mode: Post sets threshold via slider; Pre caches threshold levels so sliders can adjust audio mix independently. In 1V/oct mode: Pre = glissando enabled; Post = no glissando.163
RES (Q)knob0% – 100%Controls resonance/Q of all six filter channels. In Two-Pass mode (v5 default), 0-50% operates like classic one-pass resonator; above 50% a second resonator fades in for much higher Q and background noise rejection. Q-locking per channel is possible by holding a Lock button while turning the knob.163
Scalemenu_setting1 – 11Selects which of the 11 scales in the current bank each channel uses. Controllable via Scale CV (0-5V) or by turning the ROTATE knob in Scale mode. Each scale contains 20 notes/frequencies. Channels can be in different scales simultaneously; locked channels are unaffected.163
Scale Rotation SwitchswitchWhen enabled, channels advance to the next or previous scale in the bank each time they rotate past the top of the light ring.163
Spreadknob0 – 16Controls the spacing (interval) between channels on the light ring. At 0, channels are adjacent; each increment adds one empty spot between channels. Spread is anchored around channel 3. Subject to Morph speed. Locked channels are not affected. Also serves as a reset-position jack when a trigger is patched to Spread CV.163
Transpositionknob-6semitone – 6semitonePer-channel transposition in integer semitone steps. Hold channel's Lock button and turn its Freq Nudge knob. Env Out lights show transposition amount (red=down, blue=up). Can be applied to multiple channels simultaneously. Clear all with hold-6-Lock-buttons-2s gesture.163
VSEL JumperjumperSelects whether the SMR's internal 5V logic supply is drawn from the +5V rail or generated internally from the +12V rail. Default is +5V (86mA on +12V). Set to +12V if +5V rail is unavailable or noisy (110mA on +12V, 0mA on +5V).163

Firmware history 3 versions

VersionReleasedNotes
5.1.12020-08-25Minor bug-fix release.164
52016-12New features: 1V/oct outputs on Env Out jacks (hold ROTATE + flip to Fast); per-channel transposition ±6 semitones and fine-tuning up to 120 cents; Forbidden Notes; Two-pass resonant filter (default); new Major/Minor scale banks; intuitive bank/group color display; Env Out trigger threshold save (Pre/Post); reduced control noise.164
42016164

References 3

  1. [163]
    Spectral Multiband Resonator User Manual v1.1.1 (firmware v5)manual
    verified 2026-05-06
  2. [164]
    SMR Firmware v5 Updatesfirmware_notes
    verified 2026-05-06
  3. [165]
    4ms Spectral Multiband Resonator product pageproduct_page
    verified 2026-05-06