A-131 Exponential Voltage Controlled Amplifier

The A-131 module is the “sibling module” of the A-130 VCA. In contrast to this, it works with an exponential characteristic, but is otherwise identical. This makes it rather unsuitable for amplifying control voltages, but in most cases it is very suitable for amplifying audio signals. User interface Inputs: Outputs: Controls: A slightly “coloring” VCA … Read more

A-121-2 12 dB Multimode Filter

Like its predecessor A-121, the A-121-2 filter is a multimode filter with 12dB slope that offers separate outputs for highpass, lowpass, bandpass and notch (bandstop). Technically, the filter is a direct offshoot of the “Dark Energy II” synthesizer, which basically uses the same circuitry. How does it sound? Fine, round, pleasant and in terms of … Read more

A-120 24dB Low Pass Filter

The A-120 module is – the name “Low Pass 1” suggests it – something like the “mother of all Doepfer filters” (from a historical perspective, not from a technical perspective). The circuit is based on the famous 24 dB Moog transistor cascade (“ladder” filter). And this is actually the official mother of all synthesizer filters. … Read more

A-111-5 Mini Synthesizer Voice

The A-111-5 is not an oscillator in the traditional sense, but a complete mini synthesizer with VCO, VCF, VCA, ADSR and two LFOs. A “Dark Energy” (first generation) for the modular system! A lot of things here are patchable, but upon closer inspection you’ll see that some signal paths are exclusively internal. For example, there … Read more

A-130 Linear Voltage Controlled Amplifier

The A-130 Voltage Controlled Amplifier is a (very well-equipped) linear VCA. The “sibling module” A-131 works with exponential characteristics, but is otherwise identically equipped. It has already been shown with the mixers A-138a (linear) and A-138b (exponential) that an exponential characteristic of the amplification comes closer to our psychophysiological feeling of a “perceived linear” volume … Read more

A-111-1 High End VCO

The module is no longer in production. The A-111-1 was the high-end model among Doepfer’s oscillators and is only available on the used market. The successor model with some detailed improvements is the A-111-2. Compared to the A-110-1 or A-110-2, the A-111-1 offers expanded synchronization options, an additional input for linear frequency modulation, and a … Read more

A-121s Stereo Multimode VCF

Does this sound familiar? A new module enters the market and your first thought is: Oh, I know that one, I already have one of these, two in one housing – so what… I’ll take another look anyway: Oh, morphing between filter types, even via CV. Lots of control inputs, common for both filters, separate … Read more

A-111-3 Micro Precision VCO / VCLFO

An almost ideal VCO for small, portable module systems: The A-111-3 measures just 4 TE! At its core, it is the same VCO as the A-111-2 High End VCO II, which, however, is much more luxuriously equipped. So, again, we’re dealing with a highly tuning stable oscillator that offers pretty perfect tracking of 1V/octave over … Read more