Frequency Central Gnatophilidae Oxfordii

Gnat style VCF with LP, BP, HP and Notch responses, Drive and Clip options and multi waveform LFO.

If EDP had produced Eurorack modules, they would have been quirky, garish and killer. This is my homage. An expanded Gnat VCF with Lowpass, Bandpass, Highpass and Notch Reject responses as well as Drive and Clip options. The LFO is based on the ‘Enhance LFO’ from the Gnat, again its been expanded with multiple waveshape options. Yes, at 20HP it is twice as wide as it needs to be – you do you.

In September 2023 I was lucky enough to acquire an EDP Gnat synthesiser after questing for one for many years. I’m already the owner of an EDP Wasp, and had always wondered about the Gnat, which is a smaller version of the Wasp in many ways, but with a character all of it’s own. After decades lying unloved in an attic for decades, my Gnat required a little love to get it in full working order, so I set to work on it, after looking up the schematic. The Gnat came to life, and we fell deeply in love with eachother.

There have been a few remakes of the Wasp VCF, but never one of the Gnat to my knowledge, so with an original on hand I set out to remedy this sorry situation. The original is strictly lowpass, but it’s easy enough to add bandpass, highpass and notch reject – so that’s what I did. The Gnat VCF uses 3 gates from a CD4049, leaving 3 unused gates, so I used them to create an LFO based on the enhance LFO of the Gnat, which was used exclusively for a fixed rate PWM of the Gnat’s DCO. The LFO is expanded to offer multiple waveforms via it’s SHAPE control as well as it’s two outputs – saw/tri/ramp and pulse/square.

The Gnat was 9V battery powered, to get close to this in Eurorack I’ve given Gnatiphilidae Oxfordii it’s own onboard +/-5V power rails. This helps keep it’s character close to the original. Gnatophildae Oxfordii is big and garish, a little whacky and a little leftfield. That’s it’s joy.

DRIVE: The two audio inputs pass through the DRIVE knob before hitting the filter itself. Higher levels of drive will clip the input waveforms to the filter, as well as reducing the available resonance.

CLIP: There’s a little circuit post-filter which will simultaneously amplify and clip the filtered signal.

The combination of pre-filter DRIVE and post-filter CLIP can get you into some pretty gnarly territory! Yes, at 20HP it is twice as wide as it needs to be – you do you.

Specs: