Intellijel’s SVF 1U: Compact State Variable Filtering for the Modern Eurorack

The SVF 1U is Intellijel’s answer to the challenge of bringing full-featured filtering to the often-overlooked 1U Eurorack format. Right from the outset, the video makes clear that this is a state variable filter, meaning it offers multiple simultaneous filter modes—low pass, band pass, high pass, and notch—each available at dedicated outputs. The design is described as simple and sweet sounding, with a focus on musicality rather than over-complication.

Despite its compact footprint, the SVF 1U is positioned as a versatile tool for a wide range of sound design tasks. The video walks through the basic filter modes, demonstrating how each can be used to sculpt and animate different sonic textures. This isn’t just a utility filter for squeezing into a cramped rack; it’s presented as a creative centrepiece capable of both subtle tone shaping and more dramatic effects.

One of the SVF 1U’s defining features is its trio of output modes, allowing users to tap into classic filter responses simultaneously. The video showcases these outputs in action, with musical examples highlighting the character of each mode. This flexibility is further enhanced by the input stage, which offers three selectable clipping options via a switch: clean, soft clipping, and soft clipping with a 6dB boost. These choices let users tailor the filter’s response to different signal levels and desired saturation.

Modulation is another area where the SVF 1U stands out. The module includes two CV inputs for cutoff frequency: an FM input with an attenuverter for precise control, and a pitch input that tracks volt per octave. This dual approach enables both nuanced modulation and melodic tracking, making the filter equally at home in experimental patches and more traditional synth lines.

The SVF 1U’s modulation inputs open the door to intricate sound shaping, as demonstrated in the video. The FM input, equipped with an attenuverter, allows for detailed control over the cutoff frequency, responding well to both slow LFO sweeps and snappier envelope signals. Meanwhile, the pitch input tracks 1V/oct, enabling the filter to follow melodic lines or sequence in tune with oscillators.

By combining multiple CV sources, users can create evolving, morphing filter movements that go far beyond static sweeps. The video illustrates this by modulating the cutoff with several CV signals at once, resulting in complex, shifting timbres. This flexibility makes the SVF 1U a powerful tool for those who like to push their patches into more animated and unpredictable territory.

A highlight of the SVF 1U is its ability to self-oscillate when the resonance (Q) is cranked. In this mode, the filter turns into a clean sine wave oscillator, which can be tracked accurately via the pitch CV input. This opens up classic filter-as-oscillator tricks, useful for everything from FM percussion to melodic lines.

The video goes further, showing how feedback patching can morph the self-oscillating sine into other waveforms. By routing the band pass output back into the FM input and increasing the attenuverter, the sine wave transforms into a sawtooth. This kind of feedback-based waveshaping is a classic modular move, and it’s refreshing to see it demonstrated so clearly in a 1U context. Sequencing the resulting waveform via the pitch input adds even more sonic potential.