doepfer/a-121-2
A-121-2 12dB Multimode Filter II
Voltage-controlled multi-mode filter with -12 dB/octave cut-off slope, four simultaneous outputs (LP, HP, BP, Notch), CV-controllable frequency and resonance, and self-oscillation capability.484
Capabilities 3
- Multimode Filtermultimode-filter
- Four simultaneous filter outputs (LP, HP, BP, Notch) at -12 dB/octave; CV-controllable frequency and resonance; self-oscillation capable.484
- Self-Oscillationself-oscillation
- At maximum resonance, the filter self-oscillates and functions as a sine wave oscillator without audio input.484
- Vcfvcf
- 484
Jacks 8 (4 in / 4 out)
| Name | Signal | Voltage | Description |
|---|---|---|---|
| Inputs (4) | |||
| Audio In | audio | — | 484 |
| FCQ | cv | — | CV input for external voltage control of filter resonance, with CVQ attenuator.484 |
| FCV1 | cv | — | CV input for filter frequency modulation without attenuator; approximately 1V/octave tracking.484 |
| FCV2 | cv | — | CV input for filter frequency modulation with dedicated FCV attenuator knob for modulation depth control.484 |
| Outputs (4) | |||
| BP | audio | — | Band-pass filter output, -12 dB/octave slope.484 |
| HP | audio | — | High-pass filter output, -12 dB/octave slope.484 |
| LP | audio | — | Low-pass filter output, -12 dB/octave slope.484 |
| N | audio | — | Notch (band-reject) filter output, -12 dB/octave slope.484 |
Parameters 5
| Name | Type | Range | Behavior |
|---|---|---|---|
| CVQ | knob | — | Attenuator for the FCQ input, adjusting the modulation depth of the external CV applied to resonance.484 |
| FCV | knob | — | Attenuator for the FCV2 input, adjusting the modulation depth of the external CV applied to the filter frequency via FCV2.484 |
| Frq. | knob | 10Hz – 20000Hz | Sets the cut-off frequency of the filter manually. The cut-off frequency determines the point at which the respective filter effect appears.484 |
| Lev. | knob | — | Attenuator for the Audio In input. Beyond approximately position 5, clipping/distortion occurs with typical A-100 audio levels.484 |
| Q | knob | — | Sets the resonance of the filter. Resonance can be increased to self-oscillation, at which point the filter behaves like a sine wave oscillator even without audio input.484 |
Firmware history 0 versions
No firmware history recorded.
References 1
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[484]
Doepfer A-121-2 12dB Multimode Filter II product pageproduct_page● verified 2026-05-17