Question PAM8403 make noise (hiss)

Discussion in 'Nintendo 64' started by Modstark, Jul 5, 2017.

  1. Modstark .

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    I've got myself PAM8403 amp, all wired up correctly, but when there is no signal (console is connected to the input, but for example there is a moment of silence in the game) it hiss. Is this typical for those amplifiers or I got faulty one?
     
  2. Stitches 2 and a Half Dollarydoos Staff Member . .

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    Sounds like a bit of interference. Are you using shielded/twisted wire?
     
  3. bascocarmelo .

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    I use the one with volume control. There's definitely a low hiss but only noticeable on high volumes. Definitely interference. Check your solder job as well fam.
     
  4. Modstark .

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    I excluded interference. I've powered it from batteries and conected signal inputs to the ground (just like with volume potentiometer turned down), so there is no chance for interference. And still, there's a hiss, on speakers it's bearly noticeable but on headphones it's awfull.
     
  5. YveltalGriffin .

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    Is the circuit completely isolated? Are there any possible EMI sources near it?

    Edit: Some sources online say that the PAM8403 is naturally quite noisy even with grounded inputs, but it wouldn't hurt to shield it further. Also, if the gain is quite high you'll get worse idle hiss than if the gain is set lower. One PAM amp I used had a tiny pot for adjusting gain; maybe fiddle with that if it's got it.
     
    Last edited: Jul 7, 2017
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  6. cheese the tallest memer in town Staff Member . . .

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    You can get interference even with no inputs connected, since even the traces on the board can act like antennas and pick up noise. Make sure to use shielded wire and keep the amp/audio wires away from everything you possibly can. Also, make sure to put a cap on the input to block noise from the power supply.
     
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  7. Modstark .

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    Thanks for help, I will look into that and I ordered another version of the board with PAM8403 for tests. I will post the results.
     
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  8. Doom Modelrater Staff Member . . . Estmemed Member

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    Now that you have actual informed helps may I ask if you have checked for snakes?
     
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  9. Stitches 2 and a Half Dollarydoos Staff Member . .

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    Snakes? Is that the name of those annoying solder wisps?
     
  10. Modstark .

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    I have no idea what that mean other than long reptile. :?:
     
  11. Modstark .

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    I got the new one and after tests it is the same, so this amplifier is good only for speakers and useless for headphones.
     
  12. Stitches 2 and a Half Dollarydoos Staff Member . .

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    Some headphones don't like the high wattage output of class D amps.
     

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