Loud pop on Teensy reboot from Audio Line Out

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Matthew O'Connell

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Hi,

I am working on the final stages of a Teensy-based instrument and am trying to resolve a lingering issue. (I'll post some code and a demo when finished if anyone is interested.)

The problem I'm having is loud pop whenever I reboot the Teensy coming from the line out L/R of the audio board. It sounds a lot like static discharge (don't know if that's true or not), and it's particularly problematic because I often have the instrument plugged in to a loud PA or amplifier.

If I run sgtl5000_1.muteLineout();, then it doesn't happen, but as soon as I enable the SGTL5000 chip it's like a gunshot.

Thanks for any help!

PS: Here's an image and the github repo if that is helpful.
https://github.com/matthewthomasoconnell/themutant

IMG_2241.jpg
 
PS: I noticed that the new audio library is in beta testing. In case the right parties read this, is there any need for beta testers? I would be excited to try it out.
 
Any chance you could create a small, no-other-hardware-required program for testing this problem? Maybe just some simple tune played/looped by a single sine wave synth?
 
Thanks for the response, Paul. Here's a very basic version of my sketch and a (poor quality) video of the issue. Is that helpful?

Code: 
#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>

// GUItool: begin automatically generated code
AudioSynthWaveform       voice1a;        //xy=445,275
AudioOutputI2S           i2s1;           //xy=744,273
AudioConnection          patchCord1(voice1a, 0, i2s1, 0);
AudioControlSGTL5000     sgtl5000_1;     //xy=734,235
// GUItool: end automatically generated code

void setup() {
  
  // Initialize Teensy Audio
  AudioMemory(160);
  Serial.begin(115200);
  sgtl5000_1.enable();
  sgtl5000_1.volume(.8);

  // Play the note.
  voice1a.begin(.3,110,WAVEFORM_SQUARE);

}

void loop() {

}

 
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