G-Storm Electro SEMSVF, Oberheim SEM filter clone for Eurorack

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G-Storm Electro SEMSVF is a new Oberheim SEM filter clone and adaptation for Eurorack with CV-controlled filter response morphing.

The American Boutique manufacturer G-Storm Electro specializes in hand-made Eurorack adaption of legendary Synthesizer elements. Oscillators, filters… from many vintage synths are available for your rack for fair prices.

G-Storm’s latest Eurorack adaption is a remake/clone of the SEM filter.

G-Storm Electro SEMSVF

G-Storm Electro SEMSVF

SEMSVF is a new analog filter based on the circuits of the iconic Oberheim SEM state variable filter. More precisely, it’s a clone and Eurorack adaption of Tom Oberheim’s iconic 3080 OTA-based filter.

A characteristic resonance feedback circuit and accept-no-substitutes obsolete NOS FETS at each stage yields an absolute creamy and silky filter response.

The signal path of SEMSVF starts with two inputs and a mixer, allowing you to mix two different signals. Each input has its own mix pot. Then, it goes into the SEM filter core with classic cutoff and resonance controls. The latter will not self-oscillate without a patched input signal.

There is also the beloved morphing functionality available via the notch knob. Here, you can sweep the response from lowpass, through notch, to highpass. This can also be modulated via the dedicated CV input and attenuator. The LP|HP CV knob amount is summed with the NOTCH knob (initial mix setting) above it.

From here, it goes to two outputs, an LP/HP and a BP. This way, you can flexibly use the filtered signal and route it further to other modules. There are also other modulation sockets:

  • MOD – cutoff filter modulation w/ any polar/bi-polar signal. In the Counter-Clockwise direction, it can invert the incoming control signal.
  • KB – modulate the cutoff Frequency w/ a V/oct signal or any other polar/bi-polar mod. Self-oscillation resonance will track v/oct when KB is set to 100%.

First Impression

SEMSVF is not a groundbreaking new filter module. It is a clone of a classic that is now available for the Eurorack format. I like the implementation, and it sounds nice and creamy in the demo. Yes, a sweet spot filter.


G-Storm Electro SEMSVF is available now for $200 + shipping. Each module is handmade in limited quantities.

More information here: Reverb 

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