I wasn’t aware this “thing” existed until I saw someone post a picture of a PCB they had in one of the trading groups on Facebook. I missed out on that one, but a friend had some made up in China and sent me a PCB/panel.
RectangularThing is a fully analogue synth voice based on the reissued Curtis chips, the same ones I used for the alfa4 (3340/3320/3310/3360), but the smaller, surface mount versions. It has two oscillators with suboscillators and an interesting “rambler” waveform, LP and HP filters, two envelopes and a dual VCA.
I started by populating all of the SMD parts. The 3320 filter chips are QFN packages, which I’m getting more comfortable with now, but are still tricky. The rest of the chips are standard SO packages, so much easier. There are a lot of 0603 passives, so I took my time with it.
Next, I loaded up all the jacks, pots and switches. I had to drill out the panel as it was made for (I think) Alpha pots instead of the Alps ones I had, which have a wider bushing.
I mounted the trimmers and jumpers on the rear and configured it as per the factory units – there are lots of configuration options which I’ll explore later. When I first plugged it in, one of the envelopes wasn’t working (I’d accidentally placed a 100k resistor where a 470r should have been!) and one of the oscillators wasn’t doing anything (fixed by reflowing the passives around the 3340 chip). Once those issues were fixed, I was able to calibrate the module. It sounds amazing and is capable of some very complex sounds.
It’s now joined the rest of the TiNRS family ?