doepfer/a-101-2
A-101-2
Vactrol-based Low Pass Gate inspired by the Buchla 292. Combines a 12 dB low pass filter and VCA, switchable between LP, VCA, and LP+VCA modes. Features resonance up to self-oscillation, CV and audio attenuators, and two gate inputs for mode control.438
Capabilities 4
- Lowpass Filterlowpass-filter
- 438
- Lowpass Gatelowpass-gate
- Vactrol-based LPG combining LP filter and VCA, switchable to LP-only or VCA-only. In combined LP+VCA mode, both frequency and amplitude respond simultaneously to the same control signal.438
- Self-Oscillationself-oscillation
- Resonance is adjustable up to self-oscillation, though due to vactrol tolerances self-oscillation behaviour may vary with frequency.438
- Voltage-Controlled Amplifiervca
- 438
Jacks 6 — 5 in / 1 out
| Name | Signal | Voltage | Description |
|---|---|---|---|
| Inputs (5) | |||
| Audio In | audio | — | Audio signal input. Equipped with Level attenuator. Very sensitive in LP mode; distortion occurs above approximately position 5 with standard A-100 audio levels.438 |
| CV In 1 | cv | — | CV input 1 for controlling filter frequency (LP mode) or loudness (VCA mode). No attenuator. Does not track V/oct precisely due to vactrol non-linearity.438 |
| CV In 2 | cv | — | CV input 2 for controlling filter frequency (LP mode) or loudness (VCA mode). Equipped with attenuator CV2.438 |
| G1 | gate | 0V to 12V | Gate input 1 for mode selection. When toggle switch is in middle position (L+V/Ext.), G1 high selects LP mode.438 |
| G2 | gate | 0V to 12V | Gate input 2 for mode selection. When toggle switch is in middle position (L+V/Ext.), G2 high selects VCA mode; both G1 and G2 low selects LP+VCA mode.438 |
| Outputs (1) | |||
| Audio Out | audio | — | Audio output of the module. Carries the low pass filtered, amplitude modulated, or combined LP+VCA processed signal according to the selected mode.438 |
Parameters 5
| Name | Type | Range | Behavior |
|---|---|---|---|
| CV2 | knob | — | Attenuator for CV In 2. Scales the amount of CV2 voltage that controls filter frequency or amplitude.438 |
| F/A | knob | — | 438 |
| Function | switch | — | Three-position toggle switch selecting LP, LP+VCA (L+V/Ext.), or VCA mode. When in middle position (L+V/Ext.), the gate inputs G1 and G2 can override the mode selection externally.438 |
| Level | knob | — | Attenuator for audio input. Above approximately position 5, distortion occurs with standard A-100 audio signals in LP mode; distortion is smaller in VCA and LP+VCA modes.438 |
| Resonance | knob | — | In LP mode, controls resonance up to self-oscillation; may vary over frequency range due to vactrol tolerances. In VCA mode, only changes overall loudness. In LP+VCA mode, affects both loudness and resonance.438 |
Firmware history 0 versions
No firmware history recorded.
References 2
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[438]
Doepfer A-101-2 Vactrol Low Pass Gate Manualmanual● verified 2026-05-17
- [439]