LM 386 is a popular 8 pin IC used as Audio Amplifier in hobby circuits. It is very handy and requires only a few components to make it as an Amplifier. Its output gives sufficient sound through an 8 Ohm speaker. But one problem during its working is unnecessary hissing sound through the speaker. This hissing sound becomes a nuisance in the standby state if the amplifier is gainy and the signal level is low. But we can eliminate this hissing noise by slightly modifying the circuit design.
Fig .1 shows the standard design of LM386 Audio Amplifier.
In Fig.2, the Hissing noise is eliminated by adding a Feedback network from the output to its pin8 ( Gain pin ). This Filter feedback using a 0.01 capacitor (C6) and a 10K resistor (R3) acts as an Anti-Hiss Feedback network that eliminates the hissing noise. It gives clear audio.