| 20x40 screams "split me up" which means putting up walls (and isolating, massive ones) to produce rooms of better dimensions and isolation. You can ask in the acoustics forum what the ideal room dimensions are, how to build walls and doors and windows, and go and build those in your space.
You will want diffusion to treat flutter echo...definitely not foam (foam is basically heading in the wrong direction). You can bass trap the corners with 703 panels (e.g. GIK), but only if they need it.
Diffusors could be e.g. Auralex TFusors, homemade QRD-type diffusors made of wood, or something else you come up with or wish to pay for.
If you don't want a massive money/labor outlay just try to break up the flutters with anything you've got...store people's furniture and bicycles and whatever down there, it will break them up OK. |