PAM8403 6W Stereo Amplifier Tutorial

In the world of audio electronics, quality amplification can make all the difference in your listening experience. The PAM8403 6W stereo amplifier is a compact yet potent device that can enhance your audio projects, delivering crystal-clear sound and impressive power. This article provides a step-by-step guide on how to use the PAM8403 Class D DC Stereo Amplifier.

Step 1: Basics

This compact amplifier operates on a 5V DC power supply and delivers an output of 6W (2 x 3W).

It’s one of the most cost-effective and powerful stereo amplifiers available, provided you have the right wiring and power sources.

The IC doesn’t require a heat sink, making it perfect for custom speaker projects.

This amplifier is incredibly affordable, costing about 80 cents in the U.S and around 50 Rupees in India.

The board’s dimensions are a mere 2cm x 2cm!

Never short the grounds of the left and right audio outputs without using a proper schematic. A common ground is essential for building headphone amplifiers.

Do not exceed 6 Volts in your power supply.

Building this on a breadboard is not recommended as it results in high distortion rates.

Use coaxial cables for both the DC input and audio input to avoid horrible RF interference and poor audio output.

The amplifier board comes in two versions, one with volume control and one without. You can add your volume control using the provided schematic.

Step 2: The Connection

The board is conveniently labeled for easy connections, so there’s no need for complicated wiring.

As mentioned earlier, use a shielded cable for the inputs, while normal wiring can be used for the outputs.

Use a male stereo pin cable to connect your audio source, ensuring that you short the grounds of the audio input and voltage in.

Step 3: For TRS Pins (3 Leads)

Standard aux cables have three wires: two signal wires and one ground wire, usually black or yellow.

If you’re unsure which wire connects to which lead:

1. Get a multimeter and set it to continuity mode.
2. Connect one multimeter cable to the bottom lead of the pin and the other to any wire.
3. If you hear a beep, it means those two terminals are connected.
4. Repeat this process for the signal pins; you can interchange left and right signal inputs without affecting the circuit.
5. Solder the wires to their respective pads.

Step 4: For TRRS Pins (4 Leads)

In this case, you’ll have four wires: two for signal, one for ground, and one for +ve voltage in (intended for the inbuilt microphone of your earphones/headphones).

You only need the SIGNAL and GROUND PINS.

Step 5: The USB Cable

The USB cable has four wires: +ve V, -Ve V, Data -ve, and Data +ve.

You only need the +ve and -ve V wires.

Solder them onto the respective pads on the board, ensuring you strip off the aluminum shielding beneath the first plastic layer and the aluminum wires surrounding the colored wires.

Step 6: Connect Your Speakers

This amplifier can drive various speakers, but for optimal results, use FRS-rated 4–8 ohms, 10-watt speakers. The best results are achieved with 4-ohm 3-watt speakers.

Do not short the grounds of the speakers as it can damage the IC. Follow the circuit provided to achieve a common ground.

Step 7: Volume Control

To add volume control:

1. Get a 10K ohms Audio Taper stereo potentiometer (a dual potentiometer with a single knob for consistent output).
2. Connect the left output to the top left pin of the pot.
3. Connect the negative terminal of a 10uf electrolytic capacitor to the top middle pin of the pot and the positive terminal to the amplifier’s left input.
4. Connect the top right pin of the pot to the amplifier’s ground.
5. Connect the right output to the lower left pin of the pot.
6. Connect the negative terminal of another 10uf electrolytic capacitor to the lower middle pin of the pot and the positive terminal to the amplifier’s right input.
7. Connect the lower right pin of the pot to the amplifier’s ground.

Note: In the schematic, there are two potentiometers to illustrate the stereo potentiometer (a 2-in-1 pot).

Step 8: Common Ground

If you’re building a headphone amplifier, don’t directly short the ground pins of the output. Follow the provided circuit.

Step 9: Test It Out

Connect the power supply. You may hear slight humming from the speakers initially, which should disappear once you connect your audio cable. Enjoy your audio experience!