Deuxd - Stereo Crossmod VCF

Deuxd (I pronounce this as DUDE!) is a dual/stereo filter for Eurorack modular synthesizers. Two fully-featured VCFs in one 12HP package. WOW! But this is no ordinary stereo VCF; Deuxd has some very interesting internal routings that open up a wide range of possibilities.

The Filters: Expanding on the beautifully gritty character of the Poodleface filter section, Deuxd is a dual OTA-style filter with selectable Highpass and Lowpass responses. Each filter has a dedicated cutoff, resonance, and LP/HP control. But the fun really starts when using the BIG knob. The big knob, encircled in a red LED backlit panel, acts as the global cutoff for both filters. The big knob is the primary control, which means the outer frequency cutoff knobs act as an offset to the primary knob's position. This is the knob that will have the most fingerprints on it, I guarantee it! If you want to use the two filters totally independently and not touch the beautiful big knob, just point it straight up at noon. The noon position will then give you full sweeping control via the outer frequency knobs. One last thing about the primary cutoff knob: the switch labeled OPPOSE/SYNC is directly associated with the big knob. When Sync is selected, the cutoff of both filters will be parallel to the motion of the big knob (and voltage control signals patched into "cutoff"). When OPPOSE is selected, the right side filter will move opposite to the left. This mode sounds sooooooo gooooooood in stereo. 

The filters can be stacked, split, and summed. The SUM output takes the output of both filters and sums to mono. The dirty/filthy switch is associated with the SUM output. Select between two separate diode clipping paths for different flavors of harmonic saturation. 

The two sides are totally independent; however, there are a few internal connections that keep things interesting. The input of filter 1 (left side) has a normalled connection to the input of filter 2 (right side). This lets you process 1 signal via two different filters. Great for mono to stereo applications, or when using the sum output, as you can produce some nice twin-peak resonances. If you want to generate a variable-width bandpass filter, you will need to patch the output of the left side to the input of the right side. Make sure one side is set to hipass and the other is set to lowpass. 

The twisted modulation options. Each side has its frequency cutoff input jack that correlates directly with the frequency knob of its respective side. There is also an attenuated FM input jack that controls the same frequency cutoff. The twist is, each side's FM input has a normalled connection to the opposite side's audio input. So the audio input of side 2 is connected to the FM attenuator of side 1. This connection is broken when an external source is patched into the FM jack. Yeah, that's right.. Audio rate FM madness. Oh, the textures you will create. Once you get into this sound, you'll be using it all the time. Finally, the X-mod knob will simultaneously send the output of filter 1 to the cutoff of filter 2, and the output of filter 2 to the cutoff of filter 1. This will blow your mind.