Rossum Electro-Music Linnaeus
Stereo thru-zero state variable filter with Ping Mode
16 HP Eurorack module
Linnaeus is a stereo thru-zero state variable filter from Dave Rossum that can linearly modulate its resonant frequency through zero into negative frequency while remaining stable — opening timbral territory unattainable with exponential modulation. Cutoff is exponentially VC from sub-audio to ultrasonic; resonance (Q) is VC from 0dB to over 60dB. Each of the two channels has a continuously variable response (LP/BP/HP/Notch/Shelf) that can be set and modulated independently, while sharing cutoff and Q. An integrated morphing mod oscillator and external linear FM input drive the thru-zero modulation, and an alternate Ping Mode turns Linnaeus into a self-contained stereo oscillator and FM percussion voice.
Features
- Stereo state-variable filter with shared cutoff/Q but independent per-channel response
- Thru-zero linear frequency modulation into negative frequency, while staying stable
- Continuously variable response: LP (12/6dB), Bandpass, HP (12/6dB), Notch, Low/High Shelving
- Resonance (Q) exponentially voltage-controllable from 0dB to over 60dB (never self-oscillates)
- Integrated mod oscillator with continuously morphing wave (Off→Sine→Tri→Saw→Square)
- Mod oscillator can track the filter frequency (Track button)
- Linear Mod Index VCA, voltage-controllable from 0 to 8x
- Per-channel Response CV enable with selectable polarity (green +, red -)
- Q Compensation to tame or dial in high-Q overdrive distortion
- Ping Mode: self-contained stereo oscillator / FM percussion voice
- DC-coupled stereo inputs/outputs (process audio or CV), 20V p/p, left normalled to right
- Field-updatable firmware via WAV playback into Ext Lin CV
Controls & Jacks (32)
- Response CV
- Response/Q Comp
- Wave
- Filter Freq
- Filter Q
- Mod Index
- Osc Freq
- Freq CV Attenuverter
- Q CV Attenuverter
- Index CV Attenuverter
- Osc Freq CV Attenuverter
- Response CV Enable L
- Response CV Enable R
- Response Enable L
- Response Enable R
- Track/Ping
- Response CV Enable L LED
- Response CV Enable R LED
- Response Enable L LED
- Response Enable R LED
- Track LED
- Freq CV In
- Q CV In
- Index CV In
- Osc Freq CV In
- 1V/OCT
- 6dB/V
- Ext Lin CV
- Input L
- Input R
- Output L
- Output R
How-To Guides
- Stereo Response Morph
- Thru-Zero Linear FM Bells
- Taming High-Q Distortion
- Dynamic Index Modulation
- Ping Mode FM Percussion
Explore the interactive Linnaeus panel on BleepDex — tap any control to learn what it does.
