In bridge mode you must connect the + terminal of the speaker of channel 1, terminal + and the terminal - of the speaker to channel 2, terminal -.Additionally, in channel 1 you should connect terminal – (black) with channel 2, terminal + (red) with short cable minimum 1.5mm2 (shown as blue in image below). This is explained in the manual. Check the image by clicking here. Remember that when in Bridge mode, you can only work with impedances of 8 Ohm or higher.
