Recent Posts

Compared to the “Superphaser” A-101-3, the A-125 looks quite modest: Only half as many controls and – yes – 35 fewer sockets. But you don’t always need such complex options as the A-101-3 offers. Quite apart from the cost factor: You get 4 complete A-125 modules for the price of a single A-101-3. Oh yes: … Read more

The module is no longer in production. The A-121 is an early but very neat filter design by Doepfer. Unfortunately, the Curtis module CEM 3320 used is no longer available, so the module is no longer commercially available. It’s a shame because it has a very unique sound character and some interesting technical features. From … Read more

I often used my A-111-5 as a “stopgap” when I quickly needed another simple synthesizer voice and maybe was just too lazy to patch extra VCO, VCF, VCA, ADSR and LFOs for such a secondary voice . I was often plagued by the “guilty conscience of the modularist” when I ignored the far-reaching possibilities of … Read more

The “Slim Line” module is a version of the classic analogue noise generator A-118-1 reduced to half the width (only 4HP). As with the other “Slim Line” modules, slightly smaller buttons and sockets with narrow, round nuts are also used here. The controls are at the top and the sockets are at the bottom, which … Read more

The A-115 audio divider is a simple frequency divider that outputs square wave signals of 1/2, 1/4, 1/8 and 1/16 the frequency of the input signal. This corresponds to a tone 1, 2, 3 and 4 octaves below the input signal. User interface Inputs: Outputs: Controls: Suboscillator The A-115 Audio Divider can be used very … Read more

“Processor” here does not mean a processor in a computer, but simply an (analog) circuit that can change waveforms. Here the input signal is processed by two parallel circuits, the results of which are then mixed together: a clipper, which cuts the input signal sharply above a threshold, and a polarizer/attenuator, which can both attenuate … Read more

From a mathematical point of view, a ring modulator forms the product of two signals and then subtracts the sum of the signals from it: a * b – (a + b) Unfortunately, this great formula does not make us any smarter in terms of sound. Actually, this is “only” amplitude modulation, which, in contrast … Read more

The A-112 is a small digital module that can record, store and play back transposed audio material – a sampler in small format. In addition, the module can also be used for simple wavetable synthesis and as an effects device. The module has two small memory banks (each 64 kbytes in size) to store audio … Read more

The A-138f is a small, dual, three-way crossfader. “Three-way” here means that we have three possible input signals and one output signal. You will look in vain for the extremely sophisticated options of the A-138e, which unfortunately is no longer manufactured. The A-138f simply fades between two signals “A” and “B” and then (from the … Read more

The A-149-4 module is now the third member of the “A-149 family”. All three modules are about generating random voltages or trigger signals that go well beyond the possibilities of the random/noise modules A-118-1, A-118-2 or A-117. The A-149-1, which is based on the Buchla module 266, already has quantized voltages available that can be … Read more

The A-110-2 Basic VCO is built on the same technical basis as the “standard” VCO A-110-1 that has been available for a long time. Like the A-110-1, it uses circuitry to keep the temperature-sensitive parts of the oscillator at around 50°C. With 8 TE, it is a bit narrower than the 10 TE wide A-110-1, … Read more

The module is no longer in production. The A-107 was basically an Xpander filter (A-106-6) with greatly expanded filter modes (36 instead of “only” 16) and a digital control for morphing between different filter modes. The filter itself is of course purely analog. The A-107 works with “filter chains”: Such a chain consists of a … Read more

The Bit Modifier / Bit Cruncher is one of the digital modules that can be modulated with analog control voltages. The module is based on a 12-bit converter, which fits quite well for the intended “Lo-Fi” effects. Simply put, the module performs some purely mathematical operations after converting the audio signals into digital information and … Read more

The Xpander filter is based on the multimode filter design of the Oberheim Xpander synthesizer. With a total of 16 filter modes, it is not only extremely versatile, but also sounds very good throughout. If you only want a single filter for a small modular system, then give the A-106-6 serious thought. The filter has … Read more

The A-106-5 is a 12dB filter with two separate outputs for lowpass / notch / highpass (crossfade) and for bandpass. The filter is inspired by the Oberheim SEM filter. Incidentally, “SEM” stood for “Synthesizer Expander Module”, the SEM in 1974 was a small box without its own keyboard and originally intended to supplement a “normal” … Read more

The A-106-1 Xtreme Filter is a real fun box! The technical design is inspired by the filters of the Korg MS-20, but goes very far beyond them: Very differentiated controllable clipping (distortion) of the filter resonance, separate inputs for low-pass and high-pass mode (comparable to the A-101-1 Vactrol filter), as well as a separable feedback … Read more

The module is no longer in production. The A-105 (or A-105-1, there is now the polyphonic A-105-4) is also reminiscent of famous models. An analog SSM2044 filter circuit is used here, which was already used in synthesizers such as the Korg Mono / Poly, the Fairlight II, PPG Wave 2.2 / 2.3 and last but … Read more

The module is no longer in production. The A-101-3 phaser has two sub-units, each with 6 phase shifters (stages): The input signal runs through the 6 phase shifters connected in series and at the output, the original and the shifted signal can be mixed as desired using a “Mix” control. The output of the 6th … Read more

The Doepfer Diode Low Pass Filter is a lowpass filter with a slope of 24 dB. In terms of technical structure, it is similar to a so-called “ladder filter” (which works with a “ladder” or cascade of transistors), such as the Moog low-pass filter. Instead of transistors, however, diodes are used, which make the filter … Read more

The Opto FET filter uses optical field effect transistors. That’s a statement you have to let sink in first. Maybe meditate on it too, it certainly won’t do any harm. Until then, very quietly, the question arises as to what on earth an optical field effect transistor could be and why you need something like … Read more

After the Curtis chip CEM3320 was no longer available, Doepfer had to stop production of the A-123 24 dB highpass filter. It’s a pity, because there were simply no other 24 dB high-pass filters on the market! In the meantime, however, a replica is available with the AS3320, so that there is now a 24 … Read more

The module is no longer in production. Of all the modules that are no longer in production for one reason or another (most often it was the unavailability of certain Curtis chips, like the CEM3320 here), the A-123 filter was probably the most difficult to replace. There were simply no other 24dB high-pass filters, neither … Read more

Pimp my VCADSR! The predecessor A-141 was a more than useful module for many purposes, but there were still “wishes” when it came to the details: The A-141 wasn’t as fast and “snappy” as the legendary A-140, and loopable envelopes like the A-143-1 or A-143-2 would sometimes be nice… With the new A-141-2, Doepfer has … Read more

The module is small and interesting. A stripped down to two parameters but still flexible envelope generator with voltage control, hardwired to a linear VCA, plus a ducking function. The whole thing is also designed twice on only 8 HP. This is made possible by the new “Slim Line” format with slightly smaller buttons and … Read more

The module is no longer in production. The A-127 BOM is an extension for the A-127 Triple Resonance Filter. It supplements the module with individual inputs for each of the three filters, as well as separate outputs (per filter) for bandpass, highpass, lowpass and notch. The original A-127, on the other hand, only offered a … Read more