Soffit Design Questions

[BF]

I’m getting to the stage my soffits are ready to advance beyond a simple frame and now is the time to spill my questions. We have planned a design based loosely on John’s sketch in the infamous ‘Soffit mounting?’ thread, but with the monitors on floated concrete pillars rather than attaching a platform to the rear wall. The monitors are passive and forward ported, so air circulation will not be required.

• I remember seeing a note on hanger placement describing a /////\\\\\ layout for the hangers. Is this per soffit, or should the hangers in the left soffit be positioned as //// and those in the right \\\\?

• John’s sketch shows a 5/8” sheet of ply behind the lower portion of the wall that is faced with rigid insulation. What is the purpose of this panel of insulation being backed? Is it problematic to have the rear of this bat of insulation open to the soffit interior?

• The area in the top half behind the monitors are noted as filled loosely with insulation. What type of insulation should be used in this case and what purpose does it serve if any if we are not venting the top of the soffit to allow air circulation?

Thanks
BF

[John Sayers]

• I remember seeing a note on hanger placement describing a /////\\\\\ layout for the hangers. Is this per soffit, or should the hangers in the left soffit be positioned as //// and those in the right \\\\?

It doesn't really matter.

• John’s sketch shows a 5/8” sheet of ply behind the lower portion of the wall that is faced with rigid insulation. What is the purpose of this panel of insulation being backed? Is it problematic to have the rear of this bat of insulation open to the soffit interior?

It continues the speaker baffle and the insulation stops reflections off the back of the console coming back to you.

• The area in the top half behind the monitors are noted as filled loosely with insulation. What type of insulation should be used in this case and what purpose does it serve if any if we are not venting the top of the soffit to allow air circulation?

It dampens the box so it doesn't resonate. Just fill it with insulation offcuts or old clothes you'd sent to the charities.

cheers
john

[BF]

It continues the speaker baffle and the insulation stops reflections off the back of the console coming back to you.

Ahhh, all begins to become clear. This did not occur to me with the plane not being flush with the rest of the soffit face.

I had intended to extend the baffle downward 8x the woofer diameter, and then begin the insulated face portion. I mucked up your sketch a bit below to show the idea.

• Is this idea extending the baffle more effectively, or am I simply wasting valuable space to combat reflections by going this route? It is not too late to change the frame up a bit if need be.

• I am using two layers of 3/4" MDF sandwiched with green glue as the baffle face. Should I continue with this behind the insulated portion, or will a single layer of 5/8" ply be enough to get the job done?

Thanks again John.

[John Sayers]

no that's Ok mate - that should work.

cheers
john