"When i connect it is coming out mono sound."
What are you connecting? You should have a 1/4" TS plug into the Mackie connected via heavy gauge wire to whatever connector (Speakon?) the JBLs use.
You can test it with any passive hifi speakers: make up the 1/4" T/S - to - bare wires (or bananas, or spades), and, as the smart person said, turn the volume up slowly. There is nothing in any passive speakers that would cause you to have a mono signal; at worst, if the polarity is opposite between the left and right speakers, the sound image will be very diffuse and bass response will be greatly diminished. Again, if you're getting mono when it should be stereo, it's not the speakers or their wires.
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