Forum Rule: Always post complete source code & details to reproduce any issue!
Results 1 to 7 of 7

Thread: External amplifier doesn't work with audio shield

  1. #1
    Junior Member
    Join Date
    Dec 2018
    Posts
    18

    External amplifier doesn't work with audio shield

    Hi, I played several time my music using teensy3.6+audio shield thought the headphone jack into a beats headphone without problem. Now I'm trying to do it using an amplifier, but the sound is very low. the amplifier works well if it's connected to the pc but it doesn't with teensy audio board. why? Does anyone have an idea of why?
    thanks for the help

  2. #2
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    Posts
    8,310
    Amplifier connected to line out in some fashion and not the headphone jack?

  3. #3
    Junior Member
    Join Date
    Dec 2018
    Posts
    18
    I linked the amplifier with a jack wire through the headphones jack, I simply substitute the earphone with the amplifier. In particular the speaker is this one https://www.amazon.it/Cellular-Btspk...41083869&psc=1

  4. #4
    Senior Member+ Theremingenieur's Avatar
    Join Date
    Feb 2014
    Location
    Colmar, France
    Posts
    2,380
    The active speaker must be connected to the line output of the audio shield, and NOT to the headphones output. The latter risks to give problems with the ground potential and to destroy the SGTL5000 chip in the worst case. The ground connection of the headphone jack is a virtual ground with 1.65V DC potential, uniquely for use with headphones. Active external devices might create a short between that virtual ground and the normal GND, thus destroying the internal 1.65V bias circuit.

    But all that is written in the SGTL5000 data sheet...

  5. #5
    Junior Member
    Join Date
    Dec 2018
    Posts
    18
    Thanks for the hint, I red it but I didn't understand this.

  6. #6
    Junior Member
    Join Date
    Apr 2019
    Location
    Northwest Ohio
    Posts
    4
    In other words, the headphone jack is meant for headphones and your amplifier needs to be connected to the line out of the audio board. Those pads are on the other side of the board where it says 'Line Out'. Hope that helps!

  7. #7
    Junior Member
    Join Date
    Dec 2018
    Posts
    18
    Yes I thanks a lot you two. Now it works well

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •