doepfer/a-104
A-104 Trautonium Formant Filter
Fourfold formant filter inspired by the Mixtur-Trautonium by Oskar Sala, consisting of four parallel resonance filters with common input and output. Each filter can be switched to low pass, band pass, or off, with separate manual controls for frequency, resonance, and level. No voltage control. Frequency range per filter approximately 50 Hz to 5 kHz.521
Capabilities 3
- Formant Filterformant-filter
- Four parallel resonance filter cells each selectable as band pass, low pass, or off, replicating the formant filter of the Mixtur-Trautonium by Oskar Sala.521
- Multiband Filtermultiband-filter
- Four parallel resonance filters with independent frequency, resonance, level, and type controls summed to a common output.521
- Vcfvcf
- 521
Jacks 2 (1 in / 1 out)
| Name | Signal | Voltage | Description |
|---|---|---|---|
| Inputs (1) | |||
| Audio In | audio | — | Common filter audio input shared by all four resonance filters. Very sensitive — distortion may intentionally be used to create new sounds.521 |
| Outputs (1) | |||
| Audio Out | audio | — | Sum signal of the four resonance filters.521 |
Parameters 17
| Name | Type | Range | Behavior |
|---|---|---|---|
| Filter 1 Frequency | knob | 50Hz – 5000Hz | Sets the filter frequency. In band pass mode this is the middle frequency fM; in low pass mode this is the cutoff frequency fC.521 |
| Filter 1 Level | knob | — | Sets the contribution of this filter's signal to the mix output.521 |
| Filter 1 Resonance | knob | — | Sets the filter resonance (Q/emphasis). In band pass mode this controls the band width; in low pass mode this controls frequency emphasis around the cutoff frequency. Self-oscillation is not available.521 |
| Filter 1 Type Switch | switch | — | Three-position switch selecting the filter response: band pass (upper position), off (middle position), or low pass (lower position).521 |
| Filter 2 Frequency | knob | 50Hz – 5000Hz | Sets the filter frequency. In band pass mode this is the middle frequency fM; in low pass mode this is the cutoff frequency fC.521 |
| Filter 2 Level | knob | — | Sets the contribution of this filter's signal to the mix output.521 |
| Filter 2 Resonance | knob | — | Sets the filter resonance (Q/emphasis). In band pass mode this controls the band width; in low pass mode this controls frequency emphasis around the cutoff frequency. Self-oscillation is not available.521 |
| Filter 2 Type Switch | switch | — | Three-position switch selecting the filter response: band pass (upper position), off (middle position), or low pass (lower position).521 |
| Filter 3 Frequency | knob | 50Hz – 5000Hz | Sets the filter frequency. In band pass mode this is the middle frequency fM; in low pass mode this is the cutoff frequency fC.521 |
| Filter 3 Level | knob | — | Sets the contribution of this filter's signal to the mix output.521 |
| Filter 3 Resonance | knob | — | Sets the filter resonance (Q/emphasis). In band pass mode this controls the band width; in low pass mode this controls frequency emphasis around the cutoff frequency. Self-oscillation is not available.521 |
| Filter 3 Type Switch | switch | — | Three-position switch selecting the filter response: band pass (upper position), off (middle position), or low pass (lower position).521 |
| Filter 4 Frequency | knob | 50Hz – 5000Hz | Sets the filter frequency. In band pass mode this is the middle frequency fM; in low pass mode this is the cutoff frequency fC.521 |
| Filter 4 Level | knob | — | Sets the contribution of this filter's signal to the mix output.521 |
| Filter 4 Resonance | knob | — | Sets the filter resonance (Q/emphasis). In band pass mode this controls the band width; in low pass mode this controls frequency emphasis around the cutoff frequency. Self-oscillation is not available.521 |
| Filter 4 Type Switch | switch | — | Three-position switch selecting the filter response: band pass (upper position), off (middle position), or low pass (lower position).521 |
| Input Level | knob | — | Attenuates the audio input signal fed to all four resonance filters. Distortion appears from approximately the middle position of the input level control.521 |
Firmware history 0 versions
No firmware history recorded.
References 2
-
[521]
Doepfer A-104 Trautonium Formant Filter manual (English)manual● verified 2026-05-19
-
[522]
Doepfer A-104 Trautonium Formant Filter product pageproduct_page⚠ verified 2026-05-19 · manufacturer changed since last verified