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Audio amplifier noise and volume control

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anandhuskumar

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anandhuskumar said:
when I remove the pin there is very loud noise.
Click to expand...

I suppose this means when you disconnect all input? This allows any ambient electrical noise to reach pins 5 & 8. It can be mains hum, static from appliances, lights, etc. Maybe even radio interference.

You need to add high-ohm resistors from pins 5 & 8 directly to ground. A suitable value might be 100k to 1M. If you still get noise then try a lower ohm value. But do not make the value so low that it affects your audio signal.
 

The BA5404 has an unusual input circuit designed to make it 'coupling capacitor free' but it does need some input bias current. The schematic says BA5406 though so please clarify which you are using.

If it is a BA5406, adding resistors across the input sockets may help but I'm concerned when you say "I connected it to my phone" as that may be the cause of your problem, please explain how you have it connected.

Brian.
 

Your schematic shows a capacitor with a value of only 47uF feeding an 8 ohm speaker. Then it cuts all low frequencies below 426Hz. Do you like tinny sound with no bass?
Your schematic does not show a volume control. Add it to the schematic so we can show you how it messes up the input biasing without additional coupling capacitors.
 

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