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I have a problem with my amplifier circuit (LA4597).

I tested it (12V). It turns on and the speakers and fine and silent.

But when I try to add an audio source (RCA) within the circuit, the speakers begin buzzing. And when music is played, the output comes out very loud and distorted and is being mixed with the buzz.

I followed the diagram on the datasheet to the letter. I wanted this to play music from a phone or a PC. What am I missing?

enter image description here

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    \$\begingroup\$ Welcome to EE.SE. Per chance are you using a volume control? Or are you just connecting the inputs to a signal source? \$\endgroup\$
    – user105652
    Commented Sep 17, 2018 at 22:43
  • \$\begingroup\$ Hi! I'm not using a volume control. And yes, the signal sources are directly connected to the inputs. \$\endgroup\$
    – Ground
    Commented Sep 17, 2018 at 22:47

1 Answer 1

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You need to insert a 10K or 100K ohm stereo potentiometer in the signal path. Right now it is distorted because you are overloading the amplifier. Add this potentiometer to your circuit and adjust the volume to safe un-distorted levels.

Also, in reference to a comment below, make sure both your source and amplifier have solid signal ground connections to each other. If you hear humming sounds try using battery power to see if it clears the humming sound.

Also in reference to a comment below, you will need a 10K resistor and a 1K resistor to act as a divider per each channel. A single resistor will not reduce the signal enough.

schematic

simulate this circuit – Schematic created using CircuitLab

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    \$\begingroup\$ You may also be picking up mains (50 or 60 Hz) hum from a ground loop. Be sure that the amplifier power supply is either completely isolated or shares a good, solid ground with the signal source. To test if that's an issue, power temporarily with batteries. \$\endgroup\$
    – DrMoishe Pippik
    Commented Sep 18, 2018 at 3:46
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    \$\begingroup\$ I will add that to my answer \$\endgroup\$
    – user105652
    Commented Sep 18, 2018 at 4:37
  • \$\begingroup\$ I'll add a 10k resistor for each channel because pots are hard to find from where I live. If it's no good, I'll test it with batteries. Thanks! :D \$\endgroup\$
    – Ground
    Commented Sep 18, 2018 at 5:50
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    \$\begingroup\$ The potentiometer acts as a divider. If you are trying to replicate it with resistors you will need two - one for the pot track above the "wiper" and one for the part below the "wiper". The junction of the resistors will be the "wiper" terminal. Try attenuating the signal by 10:1 approx. 10k on top, 1k on bottom will be 11:1 which is close enough. Again, unless an answer completely addresses your question then give enough time for the Earth to rotate at least once so that the whole of humanity has a chance to answer. Then accept the best answer and upvote any other useful ones. \$\endgroup\$
    – Transistor
    Commented Sep 19, 2018 at 9:16

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