# Simple non inverting op-amp circuit to amplify mic sound don't work

#### Beau Schwabe

Joined Nov 7, 2019
130
We are both saying the same thing, one of us just doesn't realize it.

#### Audioguru again

Joined Oct 21, 2019
5,585
Years ago I worked with an expensive telephone conference system. It was loudspeaking and was full duplex (talk and listen at the same time). At the beginning of a conference it would play pink noise on the speakers and make a model of the microphones, speakers, room reflections and phone line and use the model to make adjustments before a conference call. It tried to adapt to changes. Sometimes it would get confused if somebody opened a door or if a person moved in the room, then make an odd sound as it adapted to the change.
Its local and long distance (echo) feedback elimination was fairly good.

#### Rusty Rifle

Joined Dec 18, 2019
18
What is best and cheap op-amp IC do this job? Because the sound is a little fuzzy.

#### Audioguru again

Joined Oct 21, 2019
5,585
Cheap and best are opposites.

The LM358 dual opamp that you are using sounds fuzzy because it was designed a long time ago, produces hiss noise and produces crossover distortion. It uses a low power supply current that causes the hiss, crossover distortion and a poor high audio frequency response.
It is cheap at $.47US today at Digikey. An LM833 is an audio dual opamp with none of the problems of the LM358 and it costs$.99US. Its power supply must be 10V or higher.