- any standing wave that could resonate between the width and height of the cove will be in a frequency range which will be absorbed by your acoustic wall treatments, especially the absorption at your rear wall. So little if no sound will get to, or come from the cove. Also, the level of sound coming to your ears from your monitors will be so much louder,(at any volume level) then anything coming from the window cove.
Don't ever use plywood. It resonates easily. If you need a supporting panel like that, use plaster board/wall board/gypsum board whatever you know it by. If you need a stronger panel structure, use pressed particle board. All of which you can buy cheaply from a hardware supply.
---------------
As far as using acoustical software, it's not going to show you where to place things.
For a room like yours, it will produce a lot of confusing data that will drive you crazy.
The best way to use acoustic software is for 'fine tuning'. Set up my placement scenario, playback a cd of good quality and range, then move your listening position in towards the window and away from it slowly until the bass doesn't sound 'boomy' or 'boxey'...you'll know when the bass is best. If you can, try moving a single monitor height up and then down to hear if one position is less boomy sounding. Rulle of thumb = the woofer is slightly lower then half the walls height.The tweeter level is not as important as a properly positioned bass woofer.
Once you have the best setup by ear, you can use acoustical software to fine tune if you like...but unless your really not able to arrange a setup you like, you won't need it.
Since setting up in a room your size was a new experience for me, it took me many hrs of moving shit around then finally being amazed where it all ended up for the best and most satisfying sound. My Mackies are rated to go as low as 35hz although that's debatable, but they do have a deep bass because of the rear 'passive radiator' design. So it was a real nightmare for awhile.After I had the setup right I added a small sub-woofer which really rounded out the low end. I moved it around without any success. I finally put on a shelf facing it about a foot away from my face when sitting erect. It's a front mounted woofer arrangement, so that why it works like that.
- here it is;
http://www.crutchfield.com/S-IqLMDJtbuL ... erview-tab

I'll post a pix of my setup soon. I've been wiring so things are not where they should be at the moment.
PS: if you can get a hold of one of those pro multi-tracks of known artists like Peter Gabriel or Madonna...they are all dry tracks and a great listening tool when fine tuning your placements. (PM me for more info on that)




