[Bill]

I have a 12'W X 19'L X 8'H room which will host my equipment when renovated. It was a porch at first and then turned into an insulated room. I'm thinking of returning it to a porch look (keeping the insulation of course). I have two ceiling designs in mind; which of the two would be better, acoustically speaking: 1) slope the ceiling from 8'H to about 7'H over the width of the room. This would in effect create a non-parallel surface with the floor but create different heights between each speaker and the ceiling (not much mind you). The speakers would be firing down the long dimension. 2) leaving a consistent 8' height but adding 12' long beams every two feet or so to break up sound waves. Or maybe stagger the distances between beams to help in diffusion.
  Any comments would be greatly appreciated. Thanks.

[Ethan Winer]

Probably neither.

A ceiling that rises from front to rear is good, but not side to side. And hanging beams is probably not as effective as simply putting absorbers at the reflection points. More related info here:

How to set up a room
Early Reflections

--Ethan

[Nyal Mellor]

Beams can work if deep enough and positioned correctly as they interfere with the ceiling first reflection point.

Sufficient angling of the ceiling can also push the vertical reflection from the speakers onto the back wall (behind the speakers).

If you have a CAD package you can quickly mock up some layouts. Remember angle of incidence = angle of reflection and from this you can calculate where the reflected sound will end up.