Audio Amplifier design

Discussion in 'Analog & Mixed-Signal Design' started by Arghya Ghosh, Oct 23, 2017.

  1. Arghya Ghosh

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    Aug 15, 2017
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    I am making a audio amplifier using tda2030 or tda2050. It will connected to my raspberry pi and will be on 24*7. There is a continuous hum noise when i connect it to Pi but no noise when connected to mobile. Please suggest me a way to eliminate the humm. And is there a way to keep the amplifier in a sleep state unless an audio signal is received because keeping it always on will heat it up significantly. These are the circuits i will be using. And i would power it with 5V (most preferable)or 12V.
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  2. GopherT

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    Nov 23, 2012
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    You are not getting the hum on mobile because it is battery operated. You are getting it on the Pi because you are likely using one ac adapter for the pin and one for your audio amplifier and you are getting a “ground loop”. The resistance back to the power supply ground is different on each adapter. You are either getting AC mains hum or you are getting hum from some harmonic of the ac adapter’s operating frequency.
     
  3. Dodgydave

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    Last edited: Oct 23, 2017
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  4. Arghya Ghosh

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    I am using a 12V adapter connected to a 5v buck converter. The buck converter is powering both the pi and the audio amplifier. But i have kept the audio input ground separate from the ground of the power supply. is that creating the problem?
     
  5. Arghya Ghosh

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  6. GopherT

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    I cannot tell from the explanation. Also, a simple difference in Resistance back to the adapter can cause loops. Also, buck converters are not clean power sources in general.
     
  7. Arghya Ghosh

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    Ok can you give a hint on how to check the resistance that i need to use. or what aspects should i check to trouble shoot the problem.
     
  8. Dodgydave

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    Keep All Grounds together at the same point, like a Star point, this avoids ground loops causing Hum.



    gnd4.gif
     
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  9. Arghya Ghosh

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    Thank You i will try it. Please suggest a better audio amplifier circuit if you can. And i am not using any preamp. is it necessary?
     
  10. Dodgydave

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    Last edited: Oct 23, 2017
  11. Arghya Ghosh

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  12. bertus

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  13. Arghya Ghosh

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    Aug 15, 2017
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  14. bertus

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    Hello,

    Then have a look at the ebay link and see wich chips are used.
    Fetch the datasheets of the chips and see wich would fit for your project.

    Bertus
     
  15. Dodgydave

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  16. Audioguru

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    The old TDA2030 and TDA2050 ICs do not work if the supply is only +5V (your 5V buck converter). If the supply is only plus and minus 5V (a total of 10V) then they barely work in your circuit that is designed for a plus and minus supplies that have their center connection connected to power ground and signal ground.
    I agree that you should use a modern class-D amplifier IC that works with a +5V supply and has a mute or standby pin.
     
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