# amplifying audio lm386 dumps negative part?

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 ?

• Where did you get the idea that you need those 220uF caps on the input? They are almost certainly the source of your trouble. Sep 27, 2016 at 17:20
• Show the polarity of that output capacitor on your diagram. Sep 27, 2016 at 17:22
• And while you're about it - turn the schematic around so that its "the right way" with inputs on the left, outputs on the right, ground symbols pointing down, etc. You're asking for help, so make it easy to help you by not making your schematic more difficult to read. Sep 27, 2016 at 17:24
• Look up the datasheet for the LM386, then build the circuit as shown. Read the text while you are at it. It helps to understand what is going on.
– JRE
Sep 27, 2016 at 17:27
• You have 'reverse-biased' an electrolytic capacitor, so it's no longer a capacitor ... That's why you're getting a DC offset on your output. Take that cap out & throw it away, then put a new one in the right way around (+ towards LM386's output pin). Sep 27, 2016 at 18:18