Erica Synths Fusion VCF3, Analog Filter Combined With Vacuum Tubes & Vactrols

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Erica Synths latest Fusion VCF3 module combines classic analog filtering with the warmth of vacuum tubes and the softness of vactrols

In order to shine with a filter in the Eurorack world today, it must either be extremely high quality, completely different or have something that others often do not have. The latter counts for the new Erica Synths Fusion VCF3. It’s a resonant 24dB/oct lowpass filter that is based on a design that combines vacuum tubes and vactrols. As a reminder: a vactrol is a light depending resistor (LDR) placed next to a light source.  As the light gets brighter, the resistance goes lower.

It’s a different way to add control voltage to modules but one that is smoother and softer than with resistors. The module also includes an independent audio mixer and buffered multiple that reduce the patch paths and make them easier. The highlight is a new CV recorder that records the motion of the potentiometer. An idea we know from classic hardware synthesizers like the Korg Synthesizers and others. With this, you can create very advanced filter modulations that go beyond classic envelopes or LFOs.
Erica Synths Fusion VCF3

Don’t be wrong: on the photo, you can see a VCF2 module, but it should be the VCF3 module. The one in the photo is a prototype with an older name.


  • Full analogue design
  • Vacuum tube and vactrol based filter circuit. Because of vactrol lag, the VCF will not accept audio rate modulation, the maximum modulation frequency is 10Hz
  • Input signal mixer with gain 2 for signal overdrive
  • Buffered multiple for splitting audio and CV signals
  • Potentiometer motion record unit with CV and gate outputs
  • Recorded CV multiplication and division

Review By Molten Music Technology

Erica Synths Fusion VCF3 is available now for 330€ (+21% VAT for individual customers in EU without EU VAT registration number + shipping) worldwide.

More information here: Erica Synths

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