A Couple of Designs

May 9, 2025

1U Mid Side Processor #

I’ve got everything but the panels in hand for my little 1U Mid Side processor design, so I’m starting surface mount assembly on that today. Hoping to have a couple to sell at my show in Bloomington on May 24, so on the highly unlikely off-chance you’re reading this, on the market, and planning to be there, hit me up.

This mid-side processor is really just a simple way to generate a fake stereo image from two mono signals. The “mid” signal is routed to both the left and right output equally, while the “side” output gets passed unchanged to the left side and inverted before passing to the right side. I’m interested here less in the possibility of creating a traditional stereo image and more in playing screwed up phase relationships.

For example: pass a signal to a multi-mode filter, run the low-passed output into the mid and the band-passed output into the side. This will generate weird phasey relationships that I can exploit at high volumes. I am forever trying to recreate the first time I heard Michael Pisaro’s Closed Categories in Cartesian Worlds.

The PCBs for this design came from the Germany fab Aisler because, yes, tariffs for stuff from China. It was a little more expensive than something like JLCPCB was prior to tariffs, but I cannot recommend the web interface highly enough, so at least there’s that.

Stereo Distortion #

A while back, I spun up a very simple stereo-ized version of the Non Linear Circuits Sandy Freckle, mostly because I was curious to use it as a stereo trash machine. It turns out its great at turning anything you feed it into rectified nonsense, so I’m working through a little more robust version of the design now.

The design will have a stereo input and output, and CV controlled crossfade between the clean signal and the distorted signal. I’ve also added a little wave-shaped low-passed copy of the signal into the distortion path to beef it up ever so slightly. This could prove to be a bad idea. Only one way to find out.

If you’re a sicko, here’s a link to the draft schematic. I’m trying to add some patience into my design process so I’m not ordering jacked up boards, so I’ve put the design into review purgatory for a couple of days before I start the layout so I don’t accidentally send a design to fab with a flipped op-amp or something.