ANAPHYLAXIS FILTER + CV input #2.5 - a multi-mode filter with mutant LFO & distortion

from GRM / TOTES FORMAT

The ANAPHYLAXIS FILTER is a multi-mode filter with double LFO modulator for the CUTOFF frequency based the notorious filter section of the notorious WASP synthesizer that was created by Electric Dream Plant in 1978. This standalone pedal version of the filter allows you to use it for the input signals of your choice. The FILTER MODE selector is a 4 position rotary switch (up to down: LOW PASS, BAND PASS, HIGH PASS and NOTCH) with the position indicated by small purple UV LEDs. The input signal is controlled with the GAIN control, that can boost even weaker input signal to overdrive the filter. A dedicated RESONANCE control determines the amount of RESONANCE at the CUTOFF point, that of course has a control knob as well. Furthermore the RESONANCE has two settings (EXTREME/NORMAL), selected with a toggle switch. In HIGH PASS mode the filter can self-oscillate without any input, in case you need a high frequency SINE WAVE oscillator. In that case the FREQUENCY can be dialed in with the CUTOFF control. [Optional: for 15€ extra, i add a 3.5mm mono input socket for external CV (max. 5V). This input is used to modulate the filter’s CUTOFF with external gear (as i demonstrate in this demo video of a previous build)]. But the ANAPHYLAXIS FILTER can do more, as it has 2 build in LFOs that are modulating the CUTOFF frequency, with independent SPEED and DEPTH controls, which allows to generate a more complex modulation waveform. Each LFO has a RANGE toggle that selects: SLOW (down) or FAST (up) as well a 3 position toggle switch that selects the SHAPE: SQUARE (down), OFF (middle) and triangle (up). The fast LFO range goes well into audio range and enables you to create some very interesting frequency modulation filter effects. With slower rates, especially with the triangle shape and the 2 LFOs running at asychronous speeds the even the more static input becomes ‘alive’. The SPEED of each LFO is indicated by either red or blue color in the big LED in the middle of the LFO section, to create an ambulance atmosphere or the color purple to contrast the yellow of the stencil artwork. The 1st stomp switch is TRUE BYPASS with an UV(purple) indicator LED. And if that is not enough, the 2nd stomp switch engages the DISTORTION, indicated by an orange LED. The level of the DISTORTION is controlled by the DISTORTION knob and the toggle switch next to it adds a TREBLE BOOST (up) or a HIGH CUT (down) setting to the DISTORTION. In the end of the signal path is a signal booster based on the EHX LBP1 with a global VOLUME control. The ANAPHYLAXIS FILTER runs on 9V DC and has a ‘boss style’ 2.1mm DC barrel plug socket with the negative pin inside. The enclosure is made from die-cast aluminum individually stenciled with spraypaint. Handmade by GRM for METSÄÄN.

Size: 14.5 x 12 x 5.5 cm (including height of knobs)
Input / Output: 6.3mm mono instrument jack
Power: 9V DC (2.1mm DC barrel socket, center pin negative!, for boss-style EFX-pedal PSU)

Demo videos:
youtu.be/KkcNkGbKVIw
youtu.be/o257m2VHH0M

More info, demo-video and available over here: metsn.tumblr.com