Hey, I just built my amplifier which is 3x TDA2005 3x20W. I am powering it using SMPS, yes it has input frequency filters.
The Hum problem:
I have a stereo line transformer https://www.monacor.com/products/pa-technology/signal-processing/signal-optimisation/fga-40mf/
And I don't know if to use it on audio input or amplifier output (to speakers)
Preamp:
I have 2 stereo inputs for audio, that can be connected together to make 1 stereo input, but the problem is that I need preamp that could give off 2 outputs, 1 for speakers and 1 for subwoofer (20-150 or 200Hz). I need a scheme for that or I could use a LM386 as low gain preamp.
Filter:
I tried to use low pass filter using 1K resistor and 1uF capacitor, which should cut off frequency higher than 150Hz for the subwoofer but it didn't work or I connected it bad way (I connected it at amp output)
AMP scheme (The bridge doesn't work, it will always burn out the amplifier IC, so I use the OUT + and GNDz to connect a speaker)
Speakers: 4x 6ohm 8W
Subwoofer: 1x 8ohm 30W
The Hum problem:
I have a stereo line transformer https://www.monacor.com/products/pa-technology/signal-processing/signal-optimisation/fga-40mf/
And I don't know if to use it on audio input or amplifier output (to speakers)
Preamp:
I have 2 stereo inputs for audio, that can be connected together to make 1 stereo input, but the problem is that I need preamp that could give off 2 outputs, 1 for speakers and 1 for subwoofer (20-150 or 200Hz). I need a scheme for that or I could use a LM386 as low gain preamp.
Filter:
I tried to use low pass filter using 1K resistor and 1uF capacitor, which should cut off frequency higher than 150Hz for the subwoofer but it didn't work or I connected it bad way (I connected it at amp output)

AMP scheme (The bridge doesn't work, it will always burn out the amplifier IC, so I use the OUT + and GNDz to connect a speaker)
Speakers: 4x 6ohm 8W
Subwoofer: 1x 8ohm 30W