MXN-120 Envelope Filter - SeaMoss Series

Introducing the SeaMoss series: a set of pedals using CMOS digital logic ICs repurposed as analog elements. These pedals are designed without the use of op amps/OTAs, discrete transistors, LDRs, or any other active/control elements typically found in analog pedals! Instead, CD40xx series logic ICs are manipulated into behaving as analog amplifiers and variable resistors. These circuits were inspired by vintage effects and taken on as a fun design challenge, with the added bonus that they perform exceptionally well compared to traditional implementations.

The MXN-120 Envelope Filter is an upgraded version of a vintage auto-wah, applying popular mods and, most importantly, introducing an effects loop. This opens up the possibility for a new range of sounds, such as synth-like subtractive-filter swells, and can help avoid the issue of harsh frequency spikes when using this effect with distortion pedals.

This circuit is slightly more understated compared to other classic EFs like the Mutron, but is incredibly easy to dial in and responds very naturally to your playing. It's hard to make this one sound bad.

Three knobs control the detector threshold, the attack time, and the amount of resonance. Toggle switches control the sweep direction, adjust the frequency range of the filter, and select either a low-pass or band-pass filter.

An internal switch selects whether the effects loop is included in the bypassed signal so you can use the effects in the loop even when the filter is off, or have them turn off with the filter.

Specifications:

- 9V DC power input (standard negative center, 9V max)

- True bypass 

- Dual latching foot switches

- Top mounted audio jacks (spaced for pancake cables), side mounted DC jack 

- 1590BB size enclosure