Music / Audio Coming from Circuit Board - LM1875

Discussion in 'General Electronics Chat' started by bumba000, Sep 17, 2018.

  1. bumba000

    Thread Starter Member

    Oct 7, 2015
    Hey Guys,
    So I built the single supply circuit from the datasheet and it works great around 20V. Playing around I connected it to a subwoofer which also works well. Crazy thing though ... connected to that subwoofer and turning the volume on the mp3 player to about 90% I can hear a tweeter kick on. I don't have one connected though. Turning the volume up the "tweeter" gets louder. I realized the sound was coming from the box which the amplifier board is mounted in. The closer I got to the thing I better I could hear it and it was actually the music I was playing coming out of the circuit itself. Sort of like a record and needle. Is it the capacitors I used? The resistors? Cheap knockoff 1875's?

    I know I'm not crazy. ... well that really has nothing to do with it.... I know for sure 100% there was audio / music coming directory from the circuit board.

    What's going on here?

    Thanks, John
  2. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
    Inductor or transformer would be my first guess. What is the power supply for the amplifier and is it in the same box?
  3. bumba000

    Thread Starter Member

    Oct 7, 2015
    power is dell laptop charger about 2 feet away from the circuit.
  4. ebeowulf17

    AAC Fanatic!

    Aug 12, 2014
  5. Ramussons

    Well-Known Member

    May 3, 2013