Takahiro Oishi releases Filtronix, four iconic filter models in one FREE plugin (Windows-only)

Filtronix is the first release from Takahiro Oishi (Push and Groove), a producer and developer based in Japan.

This debut plugin offers four carefully modelled analogue synthesiser filter circuits.

The four filter models aren’t from any old synths; they come from the Minimoog Model D, Oberheim SEM, Sequential Prophet 5, and EDP Wasp.

Aptly named M-Filter, S-Filter, P-Filter, and W-Filter on the Filtronix GUI.

Right now, Filtronix is available as a VST3 plugin for Windows, but pending community feedback, a Mac version could be in the pipeline.

Filtronix is currently a low-pass filter, but multi-mode support will come in future updates.

You can download Filtronix for free via Gumroad by entering $0 in the Name a fair price box (donations are very welcome).

Moog’s legendary 24dB/octave, 4-pole ladder low-pass filter first appeared in the 1960s in Moog Modular systems, but it is most famously found in the 1970s Minimoog Model D monophonic synth. The ladder filter has been at the heart of the Moog sound ever since.

The SEM synth module featured Tom Oberheim’s now-iconic state-variable filter design, renowned for its unique resonance. It offers an unmistakable blend of crisp, bright tones and full-bodied analogue warmth.

The OTA cascade filter, found in the Prophet 5, has that fat/punchy character, and while it’s capable of many things, I struggle to look beyond the poly brass stabs that the Prophet 5 does so well (it’s so good).

Finally, the EDP Wasp is one of the most visually distinctive synths ever made. This British classic features a famously unstable CMOS chip prone to aggressive self-oscillation.

To avoid common, harsh side effects of digital filters and capture the analogue character, the developer used a ZDF (Zero-Delay Feedback) algorithm.

Recreating the character and behaviour of analogue filters, including drive, distortion, and self-oscillation, comes from meticulous circuit modelling.

The upside is that we get a more accurate filter model; the downside is that it’s more CPU-intensive. The developer prioritised sound quality above all else, but further optimisation is planned to improve performance.

Filtronix also includes a tanh saturation stage featuring ADAA (Anti-Derivitive Anti-Aliasing) technology, which is another nod to the developer’s dedication to faithfully recreating the non-linear magic of analogue circuits.

CPU usage aside, four legendary filter models for free sounds great. I’ll have to wait for a macOS version, but if you’re on Windows, feel free to share your thoughts in the comments and with the developer since constructive feedback is vital at this early stage.