Friday, 22 May 2015

Mutable-Instruments Shruthi-1

22. May 2015
I've visited the site of Mutable Instruments many times in the last two years or so, and pondered and contemplated buying one of their fine synthesizer kits. But then I paused visiting them for a while, and while I was absent they appear to have stopped offering some of them. You can still download and manufacture on your own their PCB designs, but ready-for-assembly kits are gone. The only synthesizer that they still sell kits for is the Shruthi-1, and nobody knows how long stocks will last. I wonder if you can guess what happened next...

If what you guessed rhymes with "bought a kit" you're on the right track. Indeed, I just received the kit by DHL, and here's what I've got.

Full kit with PCBs, parts and metal enclosure.
Filter board. Pretty little details...
Really nice and solid metal case.
As I have written elsewhere I prefer interesting standalone synthesizers to giant modular racks, and that's why I couldn't resist adding a Shruthi to my growing collection of DIY gear. Building the device shouldn't take too long -- a few hours they say on the web site. That'll give me something to work on while I'm sourcing all the necessary parts for the ASM-2 that I also just bought a PCB for.

25. May 2015
I started stuffing the filter board. I finished the power supply and soldered all resistors. The board pretty much looks like step 10 on the very detailed step-by-step Shruti assembly instructions page. Which is why posting any pictures of my progress seems pretty pointless, come to think of it.

26. May 2015
Done! After having completed the filter board I started stuffing the control board. It has far fewer components and was completed in half the time it took to stuff the filter board. Some care is required, though, because there are parts on both sides of the board, and you need to be careful that they don't interfere with one another, especially with the display. Before mounting the display I made sure the micro controller booted correctly, as suggested in the building instructions, because it'll obscure parts of the micro controller's solder pins and render them inaccessible.

After having soldered the display in place and also the controller elements (buttons, potentiometers and the encoder), I was ready to calibrate the filter to a V/oct scale. I did it "by ear" using my DX7 as a sine wave source. It's not the most accurate way of doing this, but I managed to match the filter's resonance sine wave to that of the DX's to within a fraction of a cycle. That's good enough for me. Mounting the PCB stack into the metal case completed the project.

Building the Shruthi-1 took me about a day, and I'm not the most efficient builder. Anybody more experienced should be able to complete it in a few hours. And what does it sound like? What I've heard so far sounds very cool, especially the built-in arpeggio and sequencer. I'll make a YouTube video to show off the synth but first I'll have to waste some time with it.

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