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Thread: Chossing the right opamp for teensy 3.2 DAC audio output

  1. #1
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    Chossing the right opamp for teensy 3.2 DAC audio output

    hey guys

    i bought a teensy 3.2 some time ago and i (like almost everyone ) started a little audio project. Im using the DAC as an output and I would like to drive some small speakers with an amplifier. Im currently using a LM258 opamp as a small bit of amplification for headphone output. The output is reasonably loud and clear, but only for amplified speakers or headphones, small speakers like old PC-Beepers (http://assets.overclock.net.s3.amazo...ach158175.jpeg) cannot be driven by the amp, let alone bigger speakers.

    The opamp is configured for a gain of roughly 3, supplied by a 12V DC adapter. I attached a picture of the circuit (drawn in mspaint )

    My question is: Is it possible to drive bigger speakers with my configuration, or do i have some kind of impedance/level problem? If anyone used an opamp for the DAC output, could you recommend a good one for audio output?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  2. #2
    Senior Member PaulStoffregen's Avatar
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    These would be good ones to consider. These are very modern parts, with the ability to drive the speaker without a huge series capacitor, but they are designed for 5V power supply.

    http://www.ti.com/product/lm4871
    http://www.ti.com/product/lm4991

    For 12V power, perhaps use LM1877.

    http://www.ti.com/product/LM1877

  3. #3
    Senior Member PaulStoffregen's Avatar
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    Or if you want more power, you could step up to something like this:

    http://www.ti.com/product/lm4950

  4. #4
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    thanks ill try the lm4871.

  5. #5
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    Just wanted you to know, I bought the lm4871 and it works really nice and i can make it really loud

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