RossumLinnaeus Thru-Zero Filter

Rossum Linnaeus

Rossum's Linnaeus is an analog state-variable filter for Eurorack modular synthesizers that offers linear thru-zero FM and true stereo operation. Covering quite different ground than the much-loved Morpheus and Evolution, Linnaeus is a worthy addition to Rossum's already remarkable selection of filters.

Linnaeus offers a remarkably broad frequency range, from subsonic to ultrasonic—and what's more, it provides accurate 1V/Oct tracking across the entire range, making melodic operation easily possible in any register. There are additional CV inputs for cutoff frequency and Q as well, each with their own attenuverters.

The Linnaeus's filter "type" is continuously variable and voltage controllable, offering multiple lowpass and highpass modes, bandpass, notch, and shelving options. These "response characteristics" are independently selectable for each channel, so a host of peculiar stereo effects can be produced, from straightforward filtering to binaural panning tricks.

Perhaps the other most remarkable feature is the integrated modulation oscillator—a dedicated modulation source for performing true linear thru-zero FM. The oscillator offers continuously variable waveshape and can either track an external CV source or can directly track the filter frequency itself, allowing for more easily tunable and conventionally "musical" FM effects. And of course, the modulation index itself is voltage controllable, providing the potential for dynamic filter FM timbres from beyond this world.

After Trident and Panharmonium, we didn't expect a new Rossum module for a bit—but now Linnaeus is here, and we're excited for all the sonic opportunities it provides.

Linnaeus Features

• Stereo state-variable analog filter for Eurorack modular synthesizers
• Extremely wide frequency range, from subaudio to ultrasonic
• Precise 1V/Oct tracking across entire frequency range
• Dedicated 1V/Oct input and FM input with attenuverter
• Thru-zero linear FM possible with internal modulation oscillator or any external source
• Variable Linear FM Index with voltage control
• Voltage control of resonance (Q)
• Continuously variable filter types with voltage control
• Filter characteristics include Lowpass 12dB/Oct, Lowpass 6dB/Oct, Highpass 12dB/Oct, Highpass 6dB/Oct, Bandpass, Notch, Low Shelving, High Shelving
• Internal modulation oscillator with sine, triangle, saw, and square shapes, with FM input and option to track filter's frequency
• True stereo operation