Some special synthesizers with Antonus

A special moment is when an RSF Kobol keyboard and Steiner Parker Synthacon come together to visit Antonus’s studio.

Both pieces are very rare instruments, only few units were manufactured for a short time and unfortunately nowadays it is very difficult to find one. And it’s sad because they are instruments that sound beautiful, with a very unique sound and that also have a very beautiful aesthetic.

For the moment we did some photos and recorded videos and sounds
In these videos, the Antonus Step Brother is used to sequence the RSF Kobol and add accents and nuances thanks to the patch points of the Step Brother and the Kobol. In this video, softer and warmer sounds are chosen to appreciate the detail and response of envelopes that are particularly musical in behavior and ranges. At some moments it can make remember the sound of a Minimoog, but it has its own personality.

In this other video, the short times of the envelope are also used to demonstrate the incisive character, and the aggressive nuance of its hardsync can be appreciated. A real pleasureis listening to its musical hardsync sound.

A very curious thing happened with the Synthacon, and that is the fact that the upper part has almost the same size as the Antonus. For example this means that the Antonus Sidecar can be placed on top of the Synthacon offering a vertical construction and making possible a very deep interaction between the modular system installed at the Sidecar with the Synthacon itself.

For this video, a replica of the Steiner Synthasystem modular system the VCO, VCF, VCA and Voltage processor replicas were used to achieve harmonious sounds and textures between both instruments.  This designs are available thanks to David Ingebretsen work at the site: if you want to build Steiner Synthasystem designs this is the place to visit.

One nice thing about older synths with non-standard designs like the Synthacon is their ranges and “undomesticated” behavior unlike later synths. The result is a very wild and moody sound. Beware of volume and sound surprises!

In this other video you can see how the top measure of the Synthacon makes possible to install the Antonus Step Brother brackets for assemble a vertical configuration. Once again this enables a very deep and satisfactory interaction between both instruments.


The unique sound of the filter and how it interacts with the rest of the elements is a joy. To highlight the point that the way in which the different modulations works with the filter and the way in which the different waveforms blends together in the mixer stage make the filter offer infinite sonic surprises.