Shruti-1 SMR-4 mkII Envelopes and filter not responding to midi-triggers. [SOLVED]

I assembled the Shruti-1 following the guide and it went perfectly. The synth functioned for a few days and then i decided to take it with me on a short trip. My plan was to learn the sequencer and dont use any external keyboard. i plugged in a pair of headphones (stereo plug) and held the s1 to start the sequencer but got no sound. I fiddled in the system menu and changed some of the settings around with no success. When i plugged it in today with a mono cable and midi-keyboard i got no sound at all.

Is it possible i damaged something by plugging a stereo-plug into a mono output? Maybe the wrong filter setting in system the system menu messed up something on the voice-card?

The controls and display seems to work fine. If i turn the volume up a lot i can hear the oscillator very faint. It responds to midi in tone changes and i can edit the waveform. If i tweak the filter cut-of nothing happens. When i tweak resonance every step of the encoder produce a short snap of digital noise. The envelopes does’nt seem to trigger either.

Any idea where to start looking for errors? (I know next to nothing about electronics but i have a voltmeter and can follow instructions :slight_smile:


I had forgotten to solder some of the legs of the small IC-socket closest to the connection between the boards. After fixing that it works perfectly!

Maybe you changed the midi channel?

First, don’t plug heapdhones into the output, it is not meant for that (the output level is too high for heaphones). Unlike hardware, your ears cannot be easily replaced.

The best is to identify at which point in the signal chain something is broken, as explained in the very last section of the SMR4 mkII build instructions.