AMPLIFYING SOUND FROM ARDUINO OUTPUT.

I need to amplify the sound. I used the amplifyier shown in the picture. But the final sound was lower. The speaker I use is 3W 8 ohms. What could be wrong? What you suggest? Maybe somebody has a better circuit to suggest?
Thanks a lot.

The LM358 is an opamp, not a power amp, unsuitable for driving anything less than 1k impedance. 8 ohms is
far less than 1k.

Perhaps you need something like a PAM8403 audio power amp after it to drive the speaker?

Is there an Arduino involved?

But the final sound was lower

Lower than what?

Perhaps you need something like a PAM8403 audio power amp after it to drive the speaker?

…Right! A microphone needs a preamp with a gain of ~100-1000 to bring the millivolt microphone signal up to [u]line level[/u]. Your gain seems a little low, but it depends on the loudness of the sound and the sensitivity of the microphone.

Electret condenser mics also require power which is supplied through R5 in your circuit.

Then, you need a power amplifier to drive the speaker (usually with a gain of ~10).

Usually, there’s a volume control (potentiometer) between the preamp and power amp.

Sometimes the preamp and power amp are combined but most-often there are 2 (or more) circuits/chips.

Power (Watts) can be calculated as V2/R so with low-voltage circuits, voltage is the limiting factor. With a 5V power supply you can get 5V peak-to-peak which is 1.79V RMS so that’s a maximum of about 0.4 Watts into 8-Ohms (but there is a little voltage-loss through the amplifier).

With a bridge amplifier you can get 10V peak-to-peak for 4 times the power. (Some of the PAM chips are bridge amplifiers, maybe all of them.) And/or you can double the power by going to 4-Ohms from 8-Ohms.