Doepfer A-121d
Professional music gear - detailed information and where to buy
Doepfer
A-121d
Product Info
* Prices may vary. Check retailer for current pricing and availability.
The A-121d is a workhorse filter module for Eurorack systems. Its dual filter design and delta control make it ideal for creating evolving textures and complex tones – a great choice for experimental sound designers and those seeking classic, resonant filter character. It's a fantastic value and a solid foundation for any modular setup.
Product Description
- Doepfer A-121d
- Eurorack Module
- Dual Multimode Filter
- Contains 2 independent resonance filters
- VCF 1 with band-pass and high-pass filter
- VCF 2 with band-pass and low-pass filter
- Cutoff control for both filters and delta control for setting the frequency difference
- CV inputs with attenuators for cutoff
- delta
- filter 1 and filter 2
- Level control for input 1 and input 2
- Integrated mixer with two inputs (normalised to bandpass filters 1 & 2) and mix output
- Filter outputs for high-pass 1
- low-pass 2 and band-pass 2
- Current requirement: 30 mA (+12 V) / 30 mA (-12 V)
- Width: 8 HP
- Depth: 45 mm
PROS
- • Dual filters offer incredible flexibility for complex sound design.
- • Delta control provides unique and evolving timbral shifts.
- • Solid Doepfer build quality ensures long-term reliability.
- • Integrated mixer simplifies routing and signal management.
CONS
- • 8HP footprint can be limiting in smaller Eurorack cases.
- • Filter resonance can get quite aggressive, requiring careful control.
- • Limited filter modes compared to some more modern designs.
Product Video
Key Features
Filter Type
Multimode (Band-pass, High-pass, Low-pass)
Modes
VCF 1: Band-pass, High-pass; VCF 2: Band-pass, Low-pass
HP Width
8
Depth
45 mm
Power Draw
30 mA (+12 V) / 30 mA (-12 V)
CV Inputs
2 (Cutoff, Delta, Filter 1, Filter 2) with attenuators
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Frequently Asked Questions
The delta control is unique; it creates a dynamic frequency difference between the two filters, unlike simple parallel processing. It's a dedicated feature for evolving timbral shifts.
Yes, the resonance does self-oscillate, but it's relatively tame compared to some modules. Expect usable oscillation around the 70-80% range, but be prepared for a bit of noise.
The A-121d has a more subtle, nuanced character than the aggressive Moog ladder. It's more akin to a classic Roland filter, offering a warmer, smoother sound with a more gradual resonance sweep.
