Shurthi playing a semitone too low

Hi. Today I had the opportunity to play with my shruthi and a microkorg. I realized that the shruthi is playing a semitone lower than the microkorg. Just to be sure, I did the following :

  • controled the shruthi directly from the microkorg in order to have the same MIDI signal sent to both,
  • checked with various patches from the microkorg and the shruthi.

The microkorg has been used with several other synths, without any problem - so the problem doesn’t seem to come from the microkorg.

Does anyone knows why I get this behaviour ?

What is the value of the “Tun” setting?

i am not exactly sure, but i think microkorg has also a global tune setting. (ms2000 which uses basically the same synth engine does)
if it is not the shruhti, you might check this.

Maybe the scale “rag” setting not set to “equal”?

@pichenettes : Tun is set to 0

@schrab : Rag is set to equal

@lodebast : the microkorg has been tested and in tune with several other synths, so that rules out the microkorg.

Does it occur with all patches? Is the “test tone” (unplug the MIDI in, reboot the unit and hold S1) in tune? Maybe you could post somewhere a recording of this test tone so that I could have a look at it?

The oscillators are digital, and the same clock derives both the sampling rate and the MIDI baud rate ; so if the sample rate was off (eg: bad quartz) the unit wouldn’t receive MIDI.

I think I found the cause, but I’m not sure as my friend and his microkorg are not there anymore.

In the matrix of the default patch, route 11 is Bnd -> Osc1+2 +32.

If I set the amplitude to 0, my sound goes down a semitone (In my first post I said the Shruthi was playing a semitone lower, but it was actually a semitone higher).

So if your friend’s microkorg is gone, which controller are you using to play the Shruthi?

It looks like something is sending a pitch bend message with incorrect values. It could be the symptom of a broken pitch bend lever on the controller.

@pichenettes ok let me clarify this

At first, we tried with the shruthi + miditech 25 and the microkorg separated. There we realized the shruthi was shifted a semitone higher than the microkorg (not lower as I said before).

I suspected my miditech, so I took it out by connecting the shurthi to the microkorg - and still got the same result. Retrospectively, the shurthi might have received a wrong pitch bend information from the miditech and kept it while I plugged it on the microkorg - I didn’t try to restart the shruthi to get a clean state.

Honestly, I’m very pleased with the miditech except for the vibrato/pitch bend joystick which I find kind of weird. So maybe there is something fishy here.

if youuse pc/win , maybe u could get midiox to check what the miditech actually sends.
there might be similar tools for mac or linux.

@loderbast : that’s a good idea, I’ll have a closer lookwith alsa’s amidi utility.

For monitoring MIDI in the Mac id suggest MIDI Monitor which helped me a lot developing some neat things to come… Its OpenSOurce and free.
And it knows your favorite Synth Gear Providers Manufacturer ID!

> I suspected my miditech, so I took it out by connecting the shurthi to the microkorg - and still got the same result. Retrospectively, the shurthi might have received a wrong pitch bend information from the miditech and kept it while I plugged it on the microkorg - I didn’t try to restart the shruthi to get a clean state.

That looks like the most plausible cause to me… for some reason the miditech could have sent a “shift pitch bend to its maximum value” to the Shruthi.