As such, I would suggest you simply try routing one channel to a center setup, in this case two of your 2x12 boxes, and route the other channel to left and right into one 2x12 at each side.
This wouldn't be practical for me really. I was looking at this today however but not for and not possible with the gear I own currently.
As for true stereo live argument, I definitely think I can hear a nice stereo sound of my rig at MOST venues I play at. Some are two small or something or the sound man is lying and it's not an actual Stereo setup with the PA (yes still some in mono I find).
My cabs are on both sides of the drum kit. Im typically over on one side since my band is a trio, but I don't need to hear the actual stereo effect when we play live; it's there for the audience.
But yeah, definitely sounds like phase issue with how something is wired.
That's the same as me when playing live, and my band is a trio also and the stereo is mainly for the audience I guess too, as I just get a mono mix back in my monitors usually.
RG, do you have your effects panned hard right and hard left? Some effects units will give you a dead zone panned that way. You can try panning 75% right and left leaving 25% up the middle. That might give you a fuller, wider sound. If that doesn't work then I agree with van, check your wiring in your cabs.
Ok this might make sense about your dead zone theory. I have no control over the panning of my effects. I just know that when I use the left and right output and use stereo effects and of course goes through my stereo poweramp it comes out in stereo.
I achieve stereo by using the stereo chorus. I can also through some jiggery pokery add a delay like 10ms or what ever I choose to one side and achieve stereo using the Haas effect (you know like double tracking).
Before I started doing this, I had another delay unit that I fed the right output of my FX unit to. I stuck on a little delay then basically one side. I dropped this though since I could manage the same thing using the FX unit either via stereo delay or stereo chorus.
As for the wiring, I wired the speakers myself, however may be they aren't in phase with other two cabs that I did not wire myself and are effectively still stock?
This is possibility but I dunno why they would be wired differently from the eminence speakers I wired myself?
A sound guy said to me one time he thought my rig was out of phase at a gig. I couldn't understand that though because I use the exact same FX unit with same FX in the studio and when recorded it's in perfect stereo. So the only different with the live set up is cabs. And on this particular instance when the sound guy said one side is out of phase with the other I wasn't even using my own cabs, I was using the cabs he supplied for the venue. So go figure all that crazy stuff out!