Stereo amplifier with KIA6210AH

This is a HiFi stereo amplifier based on KIA6210AH dual audio power amplifier chip, with output power 2x22 Watts (this is the circuit's true output power and not the sound power. As you can see is fairly high). KIA6210AH chip is not hard to find. Personally, I dig it out from an old car cassette player.

Details

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KIA6210AH is a 2x22W stereo power amp, with 50dB gain and 4Ω output resistance. The output power is 22 Watt only when the power supply is 14.4 Volts. If power supply is 13.2V the output power is 19W (for each channel). At 12Volts the total drain current is approximately 3.67 Amps (1.8A for each channel). You need a power source capable of giving this current.
Don't forget to use a cooler for KIA6210AH or else you will destroy the chip.
For normal operation leave the mute cable unconnected (free to air). Alternatively connect it to the power supply.

Components

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• One KIA6210AH dual audio power amplifier.
• One 100KΩ resistor (1/4 Watt).
• One 68KΩ resistor (1/4 Watt).
• Four 2.2 Ohm resistors (1/4 Watt).
• Two 470 Ohm resistors (1/4 Watt).
• Two 1nF capacitors.
• Four 150nF capacitors (or close values).
• Two 47μF electrolytic capacitors (16 Volts).
• Two 4.7μF electrolytic capacitors (50 Volts or higher).
• One 220μF electrolytic capacitor (16 Volts).
• One 2200μF electrolytic capacitor (16 Volts).
• Two speakers (22 Watt, 4Ω Resistance).
• An aluminum cooler for KIA6210AH (I didn't make calculations for the appropriate size. If you use a large one, you will not have any problems).
• Two female RCA connectors (for the input signals).
• A Veroboard (or a PCB but I don't include a layout. Make your own).
• Wire for connections
• Solder and soldering iron

Also you will need a stabilized high current 12 Volt external power supply (3 Amps or more).

Schematic Diagram

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Here is the schematic diagram of the KIA6210AH stereo amplifier (click on the picture to enlarge).

Attention: The power supply must be between 12 and 14.4 Volts. The power on signal is generating by the voltage divider (100KΩ and 88KΩ resistors). This must be approximately 3 Volts when it is connected with KIA6210AH chip (pin 4).
According to the constructor company, you can ignore the two feedback 470Ω resistors. With out them, the gain is 50dB (maximum). According to the same source, if you use the 470Ω feedback resistors (like I did), the gain becomes 40dB and the two input capacitors must be 3.3μF. Also the two feedback electrolytic capacitors must be 33μF. As you can see in the schematic I used 4.7μF and 47μF electrolytic capacitors instead. This is not causing any problems. However, if you like you can change them to what the constrictor suggests.
Make sure you solder the two 1nF capacitors (at both inputs) as close to KIA6210AH as possible.

 

Pictures

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In the following pictures you see the amplifier connected on a breadboard (for tests only).
Here is how I connected the chip. You can also see that I used a large aluminum cooler.

And here is the whole circuit, with the speakers included.

This is the circuit from a closer look.

In this picture you see the mute cable (the red unconnected wire at the left). When you connect it to ground, the amplifier is muted. At normal operation just leave it unconnected (free to air). Alternatively connect it to the power supply (12 Volts).