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Thread: Audio High pitch buzzing

  1. #51
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    The best is, to attach the audio-shield directly to the teensy - with pins/sockets. don't use wires or breadboards..

  2. #52
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    Hi, I'm getting a similar issue - without the audio adapter though. I'm driving an OLED through SPI and have an electrolyt cap on one of the DAC outputs for a mono out signal. I'm powered via PC usb. Whenever any graphics are drawn to the screen, this is immediately translated to high pitched noise on the DAC line. The more pixels active on the screen, the worse. Is the suggestion here to use batteries or get some ground isolating thingy ?

    Also all sounds are generated as synthesis. No SD card or anything.

  3. #53
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    soerena: i'm using this here:https://forum.pjrc.com/threads/46168...icrocontroller
    without buzzing - so, it works (with ili9341 display (spi) ), and it seems your setup is different. so please open a new thread, post your sourcecode, or better a minimal version which allows us to reproduce the issue easyly.
    does your program run without connected display? if yes, just try that. disconnect it (don't change your program) - what happens ? still noisy?

  4. #54
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    Hi Frank,

    Just tried unplugging the display, and the noise almost disappears. It's still a tiny bit noisy, but this noise is more constant and not depending on the display pixels. Is there some smart way to isolate the display ?

    EDIT: for some strange reason i cant grasp, the noise is much worse the more horizontal lines I draw on the display..

  5. #55
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    Hi Everybody,

    I've been fighting with this noise for about a year. Does anybody have any success?
    I subjectively feel that the noise is related to SPI a lot. Even if you simply load a simple audio player and touch SPI pins with your hand or stick Teensy into some breadboard and connect long hanging wires to SPI pins you'll definitely hear the noise. Even fast switching digital pins will give you some.
    At some point I tried Line Out connection and there is no noise there. I feel there is something about "capless" headphone connection:
    Click image for larger version. 

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    The "ground" on the headset shows ~1.57V and it gets quite noisy if you start any SPI communication.

    The ideas are not even mine, there are smart people did some analysis here: https://forum.pjrc.com/threads/42025...eld-huge-noise

  6. #56
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    Hm no,

    with the std audioshield, and proper connections (shield soldered directly to the teensy, or with a PCB) there is no noise - never had any - even with *very* fast SPI to a display.
    Don't use a breadboard.
    Bugs in the software can also result in noise.
    Do you have enough audio buffers?

  7. #57
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    Hi Frank,

    I was referring to Part_1_03_Playing_Music.ino (the simple example). It has
    Code:
    AudioMemory(8);
    But I also tried with different other settings.
    In addition, I tried Teensy 3.2, 3.6, 4.1 - all are the same

    One thing I forgot to mention is in order to hear the noise clearly you have to do
    Code:
    sgtl5000_1.volume(0);//Mute
    And then longer SPI wires (could be between Teensy and LCD display) then louder the noise. E.g. a few millimeters ones give you very low amplitude while 6 inches will sound quite well. And your surroundings need to be quiet.
    Last edited by s_arty; 07-10-2021 at 08:19 PM.

  8. #58
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    was there any solution to this problem? I'm running a few samples from a SD card out of the DAC of a Teensy 3.2 (no audio adaptor), and I can hear this 344 Hz buzz only when the samples are playing.

    Ive tried all the things suggested:

    adding series cap out of DAC
    caps between Vin and GND
    isolating power for amplifier
    trying compiling with Tools / No USB
    increasing the gain on the sounds

    I'm kinda assuming there is no cure for this as except to get the Audio Adaptor board.....

    If anyone's gotten the buzz to go away please chime back in!

  9. #59
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    Quote Originally Posted by zumdar View Post
    was there any solution to this problem? I'm running a few samples from a SD card out of the DAC of a Teensy 3.2 (no audio adaptor), and I can hear this 344 Hz buzz only when the samples are playing.
    This is slightly different issue and I guess, well documented and expected.
    This particular thread is related to floating ground in Audio Adaptor and noise related to SPI bus.

    BTW, using line out (which does have common ground) and an external amplifier does resolve the issue. Just in case if anyone needs a workaround

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