Studio construction with soffit mounts for 20/20s

[Velvet Elvis 2]

Hey guys,

This is Velvet Elvis... had to create a new account because I forgot my password and the "retrieve password" deal was set to my email account at my old job... oops.

Anyhow, I'm starting construction FINALLY next week on the studio. I have a carpenter coming to help me frame and I want to make sure I am doing things right.

I have some questions about building soffits for my Event 20/20 passive monitors.

If you look at the drawings, you can see that the front wall of the studio doesn't sit symmetrical with the existing foundation... this causes the left and right cavities to be different sizes.

Is that an issue for the soffits?

Also, do I want to finish the wall behind the "fake" wall? IE - its a 2x4 frame with insulation right now... should it be drywalled, mudded and taped before I build the soffit wall or is it ok just to exist as is?

Lastly, when building the box for the speakers to sit it, am I understanding it correctly to think that is should be almost an exact fit on the top, bottom and sides, but that I CAN and SHOULD have air space behind it? (I am planning on closing all side of the box except the front (obviously) and putting a vent slot in the top and bottom rear).

I'd appreciate any help you can give me specific to my design, as I don't want to screw it up and the carpenter has never built a studio (not have I).

Thanks!
Ji
(Velvet Elvis)

[Velvet Elvis 2]

Hmmm... I came across something interesting...

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=98

The last statement of this thread says that the bezel is the only thing that actually effects the sound of the soffit mount...

Does that literally mean that I can build a box to basically exactly fit my speaker, SKIP putting on holes in the back (since they are passive monitors - just make a hole to run the speaker cable through), and call it good?

Can the speaker box be mounted rigidly to the wall with the bezel attached directly to the box sort of as shown here http://www.johnlsayers.com/phpBB2/viewt ... ght=soffit

Thanks... I want to make sure to get this right.

Jim

[knightfly]

Noticed you hadn't entered a location in your old profile either; we've had to insist on a few things in order to minimise the amount of time it takes to help people, here's the link

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4061

When you've done that, including editing your profile to include the area you're from, the next thing is a drawing showing the soffit end of your CR as you intend to build it - I need layer by layer, from outside the studio all the way through to the inner soffit wall, with enough detail so I could build it myself.

Also need to know how much isolation you want/need/hope for, then I can give you an answer that actually MEANS something Steve

[Velvet Elvis 2]

Steve,

Sorry about that... I missed the location part (its added now).

I have no idea how I'm planning on building the soffit. I've been looking at the drawing on John's pages about building etc and was planning on following his design.

Let me give you as much detail about the room as I can and see if that helps answer your questions... or should I say helps you to answer mine

The area I am building in is approx 20ft x 16ft.

It is a basement area that is concrete foundation on ALL sides with the only opening being the door in the bottom left of the drawing.

It is a typical foundation for the midwest, meaning 80% or so below grade with the sill plate and I-beams carrying the second floor sitting on top of the concrete foundation.

The ceiling height at the bottom of the I-beams/top of the concrete is 8ft.

The building code in Iowa required the contractor to build a 2x4 wall with standard household (R-19) insulation and plastic vapor barrier, around the outside of the perimeter of the area... so the outer most walls shown on the plans are already "built".

I am planning on building the studio walls (including the wall behind the soffit area) as follows:

2x14 construction with insulation and vapor barrier
Resilient channel
5/8 inch drywall (with acoustic caulk and backing strips)
3/4 inch drywall (with acoustic caulk and backing strips)

The ceiling is still an issue that I am working on. I am worried about what I need to do around the I-beams where they sit on the top of the concrete foundation, as that is going to be a weak point.

From there, my plan for the front soffit wall was to frame it out using 2x4s using an angle of 30 degrees off the center line for the left and right soffits.

I was planning on attaching a sealed box at listening height to the front frame... because of the low ceiling height, I was not planning or needing to angle the box.

Given the size of the room, I was planning on building bass traps/hangers under the soffits as per John's drawings on his site.

Not sure what to do with the space above the soffit other than fill it with insulation.

My speakers are passive, so heat vents aren't needed in the back, though it might be wise for future needs... don't know.

The spacing between the soffits was either going to be slat wall or bass trap... I'm not sure what would work best.

The rooms above the studio are my master bedroom (with carpeted floor), master bath (with tile floor) and the master closet (with carpeted floor).

My goal with the design is to be able to record drums, bass and electric guitar in the studio. Not all at once, but one at a time using the two small live rooms off to the right side of the studio.

I have neighbors next to that wall (above ground) approxiamately 20 feet from the edge of the foundation.

I would like to cut sound transmission enough to not bother my neighbors and if at all possible the rest of my own house.

Does that help explain the situation?

Thanks again!
Jim