Doepfer A-121s
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Doepfer
A-121s
Product Info
* Prices may vary. Check retailer for current pricing and availability.
The A-121s is a workhorse filter module, a classic for a reason. It’s a fantastic starting point for anyone diving into modular synthesis or a reliable addition to an existing system seeking a distinct, vintage-flavored filter. The stereo capabilities and Delta F control really open up creative possibilities.
Product Description
- Doepfer A-121s
- Eurorack Module
- Stereo multimode VCF
- Each filter has continuously adjustable characteristics (from low-pass to notch and high-pass to band-pass) with a switchable link function
- Filter frequency and resonance controls for both filters
- Bipolar delta F control for the difference between the two filter frequencies
- CV inputs for filter frequencies 1 and 2
- for both filter frequencies and Delta F
- each with a bipolar attenuator
- CV input for each filter with an attenuator for resonance or characteristic
- configurable via jumper
- Two audio inputs with level controls and two audio outputs
- Slope: - 12dB/oct.
- Current consumption: 100mA (+12V) / 100mA (-12V)
- Width: 12 TE
- Depth: 45 mm
PROS
- • Classic Doepfer build quality: robust, reliable, and feels immediately familiar.
- • Versatile multimode filtering: seamlessly morphs from low-pass to bandpass.
- • Delta F control adds unique movement and dynamic filtering possibilities.
- • Stereo operation expands sonic palette for wider, more immersive soundscapes.
CONS
- • Can be a power hungry module, demanding a robust power supply.
- • Limited resonance range compared to some modern filter designs.
- • The interface, while functional, is somewhat dated visually.
Product Video
Key Features
Filter Type
Multimode Voltage Controlled Filter (VCF)
Modes
Low-Pass, Notch, High-Pass, Band-Pass
HP Width
12 TE
Depth
45 mm
Power Draw
100mA (+12V) / 100mA (-12V)
CV Inputs
Frequency 1, Frequency 2, Delta F, Resonance/Characteristic
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Frequently Asked Questions
It creates a dynamic frequency difference between the two filters, leading to complex, evolving textures and unique resonant sweeps.
It's versatile enough for both; careful attenuation and CV manipulation can produce subtle warmth, while pushing resonance creates intense, distorted tones.
While it lacks some modern conveniences, the A-121s offers a distinct, characterful sound and a solid foundation for understanding filter design—it's a different flavor than the super-clean, feature-rich options out there.
