"Okay, maybe not, but it sounded funny."
LOL. that was hilarious. many of these designs are just repeats even if independently developed.** i had long forgotten about the neodan easy button series when i threw together the plan for marty that became the martysub!, but it is very similar to what neodan designed years before. i say if it is a good idea just roll with it and give credit to the extent that it can be given.
** i'm actually amazed at how similar many of the designs and concepts that we have discussed in recent years with the late zilch, parham, and others as well as in the "rallying" thread and others are to design concepts first introduced 50 or more years ago.
"How bad would it be if I slide the subs slightly closer to the center to get my mains on the outer edges? I'm probably talking 6" off perfect 1/4 spacing to do this on a 20' wall."
the 1/4 distance idea is based minimizing room mode excitation. place your subs on the pic. draw a line from the bottom to the "bouncing curve". add them together keeping the "sign" correct +/-. if you get a large value, you will be exciting that mode. if you get zero, you have no excitement of that mode.
example, at 25 and 75 placement. first order modes are excited, but cancel out.
second order modes, not excited.
third order mode, excited, but cancelled out.
four order mode is excited. but, fourth order modes tend to be fairly weak anyways, so not a big deal.
turn the plot 90 degrees for height modes. and of course the same applies for length modes.
these are only for the "axial" modes. they tend to be the worst offenders, but not always.
here is where they occur.
6" is not a big deal.
the drawing program that i use is microsoft word. that is why mine don't look all snazzy compared to some of the really slick 3d renders other folks post up.