There are a number of different Speakon connectors...the number of contacts is shown in the model number.
The amp will have 4 conductor jacks. Neutrik makes a 2 conductor version (same size) of both the jack and plug...
The contact numbers are molded into the plastic insulator that surrounds the wiring terminals. The four terminal plug will have terminals identified as 1+, 1-, 2+ and 2-. They're just names but you have to connect to the correct ones to get the desired result...
The easiest way to find out how your cables are wired is to make sure that the amp is set up for stereo operation, plug one into the speaker jack for channel 2 or your amp, plug the other end in your cabinet, plug your preamp into channel 2's input and try it out. I chose Channel 2 because QSC only connects 1+ and 1- on that one. If you get sound out of your cabinet, the speakon is wired 1+ and 1-, if you don't, it's something else.
Shut off the power amp and swap out speaker cables. Turn on the amp and try it again...
If the speaker cables are wired 1+ and 1-, you'll need to disassemble the speakon plug to make a wiring change. Unthread the collar, slide it down the cable, gently pull the Speakon plug apart...the body will slide forward (IIRC) but I may be mistaken.
Look on the insulator near the wiring terminals for markings. They're hard to find sometimes, so having a flashlight or other bright light will help.
Simple unscrew the terminal for 1- and move the wire to 2+. Make sure that the screw is tight and that you didn't miss any wire strands.
Reassemble the Speakon plug and be sure to clearly mark the cable with some colorful tape or similar to remind you that it is wired for bridging.
Test it by plugging it into Channel 1's speaker jack, set the amp up for bridging and plug your preamp in to Channel 1's input.
I apologize if there are any glitches in my description...my wife needs the computer and I'm typing faster than I want to.
Good luck and please ask questions if you have them...
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