a bit more detail would help.... a Pyramid WHAT? have you checked all of the connections? are the speakers good? any blown fuses? i'm assuming a car amp, so, do you have +12V on the BAT and REM connections? is the GND connection connected to a good ground? are the speaker wires floating? or is one side of the speakers grounded (some car manufacturers ground one side of the speakers, and some amps will go into protect mode becaise of it). what do you have for inputs?
also note that sometimes car manufacturers use speakers (or used to at one time) that have a wire jumper from one side of the voice coil to the frame of the speaker. this grounds one side of the speaker, and needs to be removed before using a bridged output of a car amp.