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Thread: Output dac directly to trrs headphone

  1. #1
    Junior Member
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    Output dac directly to trrs headphone

    Hi, I am building a project that will receive information (voice) from a microphone connected to TRRS on one side, encrypt the voice and output the encrypted voice to TRRS on the other hand.

    I have TEENSY 3.2 and the audio shield, now I want to insert the plain voice through the TRRS of the audio shield, perform the encryption in the TEENSY and then output the encripted voice out to the DAC1 to which another TRRS with headphones (normal iphone/galaxy trrs headphone) will be connected to .

    Adds a drawing to how it should all connect:
    Click image for larger version. 

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    Now for question:

    I'm relatively new to electronics and I'm not sure if I can connect the DAC directly to the headphones or will I burn the headphones and the DAC?

    Can you help me with a schematic How should everything be connected plus an explanation of why this should be connected?

    Thanks GAY

  2. #2
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by gay View Post
    not sure if I can connect the DAC directly to the headphones or will I burn the headphones and the DAC?
    The built in DAC on Teensy 3.2 is not capable of directly driving headphones.

    It's output impedance is too high (weak) to drive the headphones, and it has a DC offset. Neither of those are good for direct connection, but if you do try anyway, usually the result is a very faint output that can barely be heard. Damage to the hardware is rare.

    Generally you would need to use an amplifier chip between the DAC and headphones.

  3. #3
    Junior Member
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    Quote Originally Posted by PaulStoffregen View Post

    Generally you would need to use an amplifier chip between the DAC and headphones.
    If I add the MAX9812L like this:
    Click image for larger version. 

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    Is i't suuposed to work fine? (ie fix the DC offset and make the output strong enagh)? (or do i must use MAX98306 amplifier or LM386 amplifier , I kind of lost with the amplifier I realy need some help with it.)

    If not on which amplifier you recommend for this situation?

    thank you,
    Gay
    Last edited by gay; 12-07-2018 at 07:46 AM.

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