The Shruthi-1

Shruthi-1 Hybrid Synthesizer

Type: Hybrid Analog Subtractive, Digital Wave Table

1 Digital card for FM and wave table generation providing:

  • Oscillators: 2
  • Envelopes: 2
  • LFO: 2
  • Monophonic
  • Patches RAM: Limited To ATMEGA644 flash
  • Editing: USB
  • Arpeggiator
  • Sequencer
  • Designed by Olivier Gillet and Mutable Instruments:
  • Open Source Hardware & Software

Analog filtre card:

I normally would not have built a Shruthi-1 synthesizer. It is not that they are poor, or the sound is bad. Far from it! This little mono-synth has been given rave reviews when it first came out. It is a sound powerhouse, that is beautifully designed. Best of all, it fits into a large coat pocket that you can carry with you for portable synth jams or rocking the dance hall. These make an excellent synth for builders with minimal experience, but I said I would normally not build one, and I say that because the Ambika is basically a 6 voice polyphonic, multi timbral Shruthi-1.


Building an Ambika and a Shruthi with the same filter cards don’t really get you anything extra. Although the Shruthi is still around, it has analog filter boards that are not available in the Ambika. Including an awesome design by Scott Ryder (aka Old Crow), that is based on the Yamaha CS80. And that, is why I built it. The Shruthi with the SMR4 filter is the exact same sound I can get out of one voice card in the Ambika. But this CS-80 filter produces a totally different sound altogether.

Bare PCBs, main n the left and CS80 filter board on the right

Just like the other open source projects on this site, you can download the PCB, case files, and firmware order or scrounge all of the parts and built this whole thing yourself. I even found a local laser cutting guy who can make the cases for $7 each. Of course, they only come in white…

I Use this small synth in concert with an Ambika, PreenFM and Linnstrument control surface. Basically two small bags have everything I need for an evening out with the other synth-heads. It is a lot of fun, and adds a warmth of analog goodness to the mix.

With the Linnstrument