LP2+Delay high pitched noise?

So I over came my LCD issues only to come up with a new issue, being that the unit is only outputting a high pitched whine. All the LED’ss and the knobs etc function properly and correspond to the data on the LCD, but I can’t get a sound out of it at all, except when I adjust the Delay parameters the whine changes in pitch and volume etc, no synth sounds, no nothing. Any suggestions on what to check out? Barry

Hi Barry, if you take some photos and post them here , then people can take a look.

Check the image at the bottom of the troubleshooting section of the build instructions.

Let me konw at which point you observe something that doesn’t match the description.

Well my pcb has the screen printing from the image at the top with the professor, not the little boy is there a difference?

Circuit is exactly the same.

Okay so new question, this high pitched whine was the delay immediately feeding back as I powered the unit on. Due to my own silliness i didnt realize my Midi channels were not in sync. Once I got my midi all up and running, I then was able to get into the sub menu’s to switch the filter setting to “DLY” it was fine, but everytime I powered up the feedback would start. So I eventually figure out how to save the settings so the internal menu settings are locked for power up, so in power up the unit starts to feedback, and as soon as the title page comes up “Mutable Instruments” the feedback cuts and all is fine. Is this all normal? Also, other question is in the CV menu when I scroll through the choices the whole screen goes glitchy, not normal right? Thanks b

  • The feedback is normal. If the filterboard setting is not set to dly, the DAC that controls the delay time/feedback level does not get any data fed to it and the delay is freewheeling into feedback. Feedback might occur in the short interval between the time the unit boots, and the time it reads its settings and switch to the “dly” mode. This is one of the drawbacks of having a simple system which is not “hardwired” for a specific filter board.
  • I assume that the “glitching” you describe is trying to enable the programmer. If you try to use this function without an actual programmer being connected to the unit, it’ll read random values for all parameters. Don’t do that!

All is fine. The Shruthi doesn’t boot (and thus can take control) as fast as the PT2399 Delay chip, so its a bit of time out of control. Mine makes sometimes a Star Trek Door Sound…