Soffit half finished - need input

[jmorken]

So I'm building my soffit according to Barefoot's technique in this thread. the monitors will be strapped to sand-filled columns behind the front soffit. The space behind the soffit will be filled with bass trapping and will have insulation wrapped around the speakers. I have 3/4" particle-board for the soffits.

My question (in so many words) is this:
What do I do with the space surrounding the soffits?
Should it be solid all the way to the walls/floor/ceiling?
If not, what material(s) do I use to continue the face of the wall to the floor/wall/ceiling?
How far should the soffits extend to this change of material?

I've attached a picture of my progress thus far (which I'm not afraid to redo) and sketch-up dimensions of the space and soffit.

Thanks in advance for your gracious help.

[Ro]

so euh, you started cutting wood before actually having a plan?

[jmorken]

so euh, you started cutting wood before actually having a plan?

yep.

There's less than $20 worth of wood there, so I just wanted to mock it up to see that a) it fits without making my workspace claustrophobic and b) that all my geometry is correct.

I know in John's soffit design he opens up the front wall along the floor for bass trapping, but in his design the speaker cabinet is sealed from the rest of the cavity. I'm just wonder how this technique would apply to Barefoot's soffit design.

[jmorken]

bump?

[lilith_envy]

What happening at the back of that photo? Is it an open space?
If so... Do you need bass traps? do you even need soffits?
Are you having lack of bass issues?
lil