I built the Velleman K8060 kit.
Everything has been checked several times, the direction of the components, their value, the voltages of the transformer, etc.
Everything is in order.
The bias of RV1 has been set to 10.2mv (tested with a voltmeter).
The speaker is 8 ohms and was plugged in the right side.
The audio source is an mp3 player, which works great on another amplifier.
As soon as I sent sound (at a low level) to the input of the IN and GND terminals (connected in the right direction), the TIP147 transistor immediately smoked and burned.
The radiator is properly isolated from the two transistors. Nothing touches. The thermal paste is in place. I have already made many other montages, without any problems.
I do not understand why.
Thank you very much for helping me understand what happened!