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Simple audio amplifier 2x 100W RMS

    This is a simple but powerfull audio amplifier with high output power of 2x 100W RMS (not P.M.P.O.). Speaker impedance is 4 ohm. Amplifier works in AB class. The amplifier uses TDA7293 integrated circuits with MOSFET outputs. They are similar to the TDA7294, but have increased the maximum allowable voltage from 100V to 120V and are equipped with a clipping detector. Below is a schematic diagram of one channel of the amp and a classic power supply for the entire amplifier (both channels). Stereo logarithmic potentiometer P1 is used to adjust the volume. LED1 indicates signal clipping. This may be caused for example by reduced the supply voltage of the amplifier, excessive ripple in the filter capacitors (their capacity is too small) or simply by too strong input signal. Each channel has its own indicator. Indicators of clipping may be omitted. Amplifier's power supply is symetrical, with a classic mains power transformer. 100n capacitors should be placed as close as possible to integrated circuits to avoid amplifier to oscillate and cause distortion or overheating. Mute and Standby inputs are not used. Even without the use of them there were no significant impulses during power on or off. If you need, you can use those inputs to implement the standby switching of the amplifier.

     Warning! The device is powered by mains voltage. It is necessary to use an appropriate fuse. When poor design, dangerous mains voltage can reach all parts. Supply voltage and the secondary voltage of the transformer can also be dangerous. Capacitors can remain charged even after shutdown. All you're doing you do at your own risk and responsibility.

The schematic of the simple audio amplifier 2x 100W RMS and its mains power supply.


First tests of one channel

Universal PCB board with both channels of the 2x 100W audio amplifier.

Testing both channels with temporary capacitors

New capacitors ready to install. Documentation of the mechanical amplifier design will be added later ...

Video - testing a simple amplifier 2x 100W RMS. Speaker, dummy load and test of the clipping indicator.

Added: 27. 9. 2012