Loudspeakers switch off on their own

Hello, I installed new speakers in the front of my Opel Corsa C (Bj 2001) today (JVV). When I then tested the speakers during a ride (radio loud) the speakers turned off from the same and after a shorter time they went again. This happened a few times until they didn’t turn on at all. I then switched off the radio and switched on again and then they went again for a short time. My subwoofer remained however all the time. I connected the loudspeakers normally to the radio, used the existing cables quite simply. In the back I still used the Orginale Lautaprecher which however always went out. However, I don’t know why this happened. Have a Pioneer Radio (4x50Watt). Who could help me. Thanks in advance!