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VCA Compressor By Bob Thomas
Published January 2023


This quality analogue processor offers precise and intuitive control over your compression.

Founded in 2004, Oliver Gregor’s Dusseldorf‑based Rockruepel Pro Audio now offer three products: the Comp.two, which is a high‑end, dual‑mono/stereo vari‑mu compressor; the, a stereo/dual‑mono analogue mastering limiter; and, launched fairly recently, the The last, which is slightly more wallet‑friendly than the others, is a mono, analogue VCA compressor, and is named for its interesting side‑chain filter, of which more below. In developing the, Gregor worked closely with two Grammy‑nominated mastering engineers, Germany’s Stefan Heger and Las Vegas‑based Luca Pretolesi, whose personal contribution to the project is acknowledged by the presence of his StudioDMI logo on the’s front panel.

Freq Out

As is the case for all Rockruepel products, the is designed and manufactured in Germany. Its high quality is evident throughout — in the mechanical design, hardware, and electronic components, of course, but also in the fit and finish of its physical construction, both internal and external. It all inspires precisely the sort of confidence one should expect of a device in this price bracket.

The most obvious clues to the’s headline functionality are two horizontally‑mounted faders on the left‑hand side of its front panel. The upper fader sets the corner frequency of the side‑chain high‑cut (low‑pass) filter, and the lower one sets that of its low‑cut (high‑pass) filter. Each is a 12dB/octave filter, and its frequency range can be switched to any one of three bands, labelled High (1.5 to 20 kHz), Mid (150Hz to 2.3kHz), and Low (20 to 200 Hz). A pair of tri‑colour LEDs indicates which band is currently selected for each filter. This dual‑filter arrangement obviously gives you the option of applying variable high‑pass, low‑pass or (when both faders are in play) band‑pass filters, but also means the faders can be set very precisely around the desired frequency.

The two filters, which can either be used on their own, or to shape the compressor’s control signal, each have a fader and a switch to focus the fader’s range in a specific part of the frequency spectrum.The two filters, which can either be used on their own, or to shape the compressor’s control signal, each have a fader and a switch to focus the fader’s range in a specific part of the frequency spectrum.

The remaining four switches, each with ‘illuminate when active’ LEDs, form a line at the bottom of the front panel. The first takes the in and out of hard bypass, and the second activates the Listen function. This routes the side‑chain signal directly to the outputs, which obviously allows you to monitor the filtered side‑chain signal being sent to the compressor, but also means the can be used as a high‑quality high‑pass/ low‑pass/ band‑pass filter. If side‑chain filtering is not...

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