I made this project for testing amplifiers and cd-players. The output of those comes on the input of this box. Therefore I don’t have to risk my expensive speakers to test a expensive amplifier.
The RCA inputs are amplified by a build in 2x10W amplifier. I can choose between the output off the amplifier and the speaker inputs with a switch. The output of the switch is connected to a dummy load. With another switch the speaker can be switch on and off. To protect the test speakers I made a dc protection circuit
Pictures:
The dummyload:
12V power supply:
Dc protection:
2x10W amplifier:
This project was published in the SchemaTheek magazine of may 2009 (Dutch).
Dutch 
