I am amplifying and audio signal with ac levels of around +-0.3V.
This signal also has DC level of 1.2V
I used 2 DC block capcitors because I saw the input should be ground referenced.
The output of this circuit that I measured was for some reason also DC bias [even though I used a dc block capcitor aswell] but the sound was awful and I think it is because the output has lost all its negetive sound .
Also first time I noticed this amp doesnt have -Vsupply but ground.
I know it is also got truncate but I doubt thats the reason .
I know there is FFT on the right side but this is not FFT of the audio its in time plain .
I thought maybe to lose the DC blocks in the input and to put 1 or 2 diode in series to lower the DC but I dont think it will end up well.
Also thought to replace LM386 to LM370 but the input resistance is 2M .
any solutions How can I get the negative part ?
Best Answer
The short section of audio shown looks OK. It is suffering from clipping on both the bottom peaks AND the top peaks too. Clipping indicates that you're applying too much signal at the input. Such overdrive can result in your "awful" distortion.
Don't forget that this chip has a minimum gain of 20 dB. And don't forget that any input signal extending more than 0.3v below ground is outside acceptable territory.
Those 220uf input caps are overkill, and might cause strange effects. I'd suggest reducing them to 0.33uf non-polarized types.