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Thread: Mic GND and stereo jack HPVGND in stereo+mic jack

  1. #1

    Mic GND and stereo jack HPVGND in stereo+mic jack

    Hi.
    There is some way to use the mic input of Teensy Audio adapter with the headphone jack ground (HPVGND) ?
    The problem is that with stereo + mic jacks there is no way to have 2 grounds one for mic and other for headphones output.
    If I wire the mic/bias to the mic ring of the jack then headphones start "screaming" and I disconnect to avoid burn something.
    Thanks.

  2. #2
    Senior Member
    Join Date
    Jul 2020
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    557
    Quote Originally Posted by Stendall View Post
    Hi.
    There is some way to use the mic input of Teensy Audio adapter with the headphone jack ground (HPVGND) ?
    The problem is that with stereo + mic jacks there is no way to have 2 grounds one for mic and other for headphones output.
    If I wire the mic/bias to the mic ring of the jack then headphones start "screaming" and I disconnect to avoid burn something.
    Thanks.
    The headphone output is as I understand is not ground referenced, ie HPVGND is a DC level that must
    not be connected to 0V ground (well not at DC for sure).

  3. #3
    Thank you Mark.
    I suppose I will have to "dump" the Teensy audio adapter (again, first screwed and now this) and instead use a uda1334a + pcm1808 + Mic bias and preamp circuit or similar. Hurray!
    Can't see any other way to fixit with the sgtl5000 board

    Best regards.

  4. #4
    Senior Member
    Join Date
    Aug 2019
    Location
    Melbourne Australia
    Posts
    190
    I built a personal audio monitor for vocal practice and originally used a stereo + mic jack and ran into feedback both mechanical (from the mic being physically attached to the headset) and electrical (from mic and headphone wiring sharing the same cable jacket).

    Ok, the output stage has some (intentional) serious grunt as will tickle the ears before any clipping occurs. I use a separate mic that hangs on an ear and JBL headphones the latter being of far superior quality than the headphone part of any headset.

    More fiddly but if you want quality, you gotta work at it.

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