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-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-121 Multimode Filter

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

A-107 Multitype Morphing Filter

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

A-106-6 16-fold VC XPander Filter

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

A-106-5 12dB SEM Type VCF

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

A-106-1 Xtreme Filter

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

A-101-6 Opto FET Filter/Phaser

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

A-127BOM Breakout Module

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

A-104 Trautonium Formant Filter

The module is inspired by Friedrich Trautwein’s Trautonium, a forerunner of today’s synthesizer. The Trautonium became particularly well-known through the work of Oskar Sala, who used it to produce the film music for Hitchcock’s “The Birds”. However, other composers of the 20th century also composed for the trautonium, such as Paul Hindemith. In principle, the … Read more