Help with Acoustic Treatment of STEALTH BOMBER-shaped room

[majortom]

I'm looking for some ideas to maximize the oddly-shaped room I have. I plan to mix and record in the same room. I could duck into the vocal booth if I wanted to isolate myself a little. The ceilings are 11' high and a little irregular as well, containing some 2'x2' concrete cross-beams in a few places.

I was thinking of moving the 5x5 DIY vocal booth from position V1 to V2. It's made of 3/4" plywood and the inside is covered with 4" acoustic cotton, but that's another story. When the door is open, it's essentially a giant bass trap. How good I don't know, but big.

I was thinking I would do most of my tracking in the 12x9 space along the bottom of the picture. I have some plywood and a big-old conference room table I thought I could stand on end in the top-left corner and reflect some of the hi-freq sound from one "wingtip" to the other, bend it around the "L" so to speak.

I thought maybe I'd set up my monitors close to the top left corner and point the speakers toward the "wingtips" of the bomber-shape (along the longest sides). I would set up my mixing station at a 45 degree angle to the two walls. Is that weird?

Anyway, I was hoping I could use the odd shape of the room to my advantage... to make it sound bigger than it is.

To work with, I have 6 GIK Acoustics tri-traps, 2 GIK panel traps, 3 "gobo-ized" Realtrap mini-traps, and a bunch of 2'x4' 4" thick sheets of acoustical cotton mounted on cardboard backing.

Any general or specific advice would be appreciated. If I should post this somewhere else, let me know.

Thanks.

[FalconerHK]

I don't have any advice for you, but I love the "pissy neighbors" item on your layout.

[Ethan Winer]

Tom,

> I'm looking for some ideas to maximize the oddly-shaped room I have. <'

It's not clear if by "maximize" you mean get the best sound inside the room, or not piss off the neighbors, or both. Sound isolation and acoustic treatment are completely different and are mostly unrelated.

> I thought maybe I'd set up my monitors close to the top left corner <

Symmetry is key, and the most symmetrical place in that room is the bottom. So I'd set up with the loudspeakers at the bottom facing up toward the top. Then set the mix position so your ears are about 8 feet from the bottom wall you're now facing. A side benny is this also puts the speakers farther from the "pissy neighbors" wall. (I like that notation too. )

You'll also need to treat the first reflection points on the side walls (and ceiling), so for the glass side you'll need to rig up a stand of some sort, or hang those panels from long wires attached to the ceiling. Or any other way you can get the absorption at the correct location.

--Ethan

[bpape]

I about fell off my chair when I saw the 'pissy neighbors' annotation!

If you want to move the booth you certainly can. The only issue I see with that is that the corner you're wanting to put them in is one of the 2 opposite corners that provide the longest diagonal in the room (lowest mode). I'd want to treat that corner with some bass control.

I agree completely with Ethan about symmetry. Unfortunately, with the speakers set up down there, you'll have glass to one side and wall to the other.

While not optimal, I'd probably put the speakers along the left side of the room firing away from the window. That still gives you good symmetry in front of you, leaves the booth where it is, let's you treat the 3 deep corners (v2, and the top left and bottom left corners with the 6 Tri-Traps.

Use the 3 Mini-Traps set up behind the mix position on the back wall in a straight row pretty much to give some bass control behind you.

Acoustical cotton on side walls for reflection control, and the other 2 GIK's behind the monitors in front of the window.

Lots of options in that room but IMO, sitting in the corner in a slanted fashion is not one of the better ones.

Bryan

[majortom]

When I said "maximize" I meant getting the best sound.

I'm glad you guys find it amusing that I've got pissy neighbors :-)

Actually, they're not around on weekends, so that's when I do my tracking. Mixing volume is not loud enough for them to complain... yet.

The glass side is not all glass, floor to ceiling (sorry for not being precise). There's a 2.5 foot ledge that I could sit panels on. There's also some metal frames and a little space between windows, that I could use for mounting.

Assuming I placed my "ears" 38% of the way up from the bottom wall (the 8 feet Ethan recommended)... So, if I were able to cover up the glass in the bottom lobe with plywood, up until the first reflection point, about 6-7 feet from the bottom, would that make it symmetrical enough? I'm not as concerned as much about the symmetry after the first reflection point, right.

Thanks guys. Your expert advice is much appreciated.

[majortom]

... or if I lined the glass side, up to the first reflection point with absorbtive (is that a word) panels and did the same for the wall side would that help the symmetry? No plywood.

[bpape]

It would help some - but the glass is still going to resonate and give you a different bottom end response than the drywall on the other side. This can cause a shifting of apparent centering of lower voices.

What Ethan suggested is certainly not a bad ideal at all. It does leave some additional room for tracking. I'm just trying to get you the most symmetric mix position as possible.

If it were me and you decide to go with what Ethan said, I'd plan for basically the entire window back to your seated head position to be covered with at least 2" panels and the same on the other side. A bit of space between them and the windows will help extend the response deeper and help balance things left to right.

This still leaves the issue of not being able to deal with the long diagonal mode in the new booth position.

Bryan

[majortom]

Originally Posted by bpape

It would help some - but the glass is still going to resonate and give you a different bottom end response than the drywall on the other side. This can cause a shifting of apparent centering of lower voices.

What Ethan suggested is certainly not a bad ideal at all. It does leave some additional room for tracking. I'm just trying to get you the most symmetric mix position as possible.

If it were me and you decide to go with what Ethan said, I'd plan for basically the entire window back to your seated head position to be covered with at least 2" panels and the same on the other side. A bit of space between them and the windows will help extend the response deeper and help balance things left to right.

This still leaves the issue of not being able to deal with the long diagonal mode in the new booth position.

Bryan

Having my mix position in a different spot than where I'd do most of my tracking is a plus. Would you put the mix position in the center of the 21' wall with my "ears" about 6.5 feet off the glass. Or a little higher, maybe six feet from the top wall, so the rear wall would be more symmetrical.

I could even rig up some 6'x4' plywood on stands to setup across the opening to the 9x12' space when I'm mixing to close it off and make it more symmetrical.

Could I still track in the bottom 12x9 lobe, in your opinion?

I could treat the top-left and bottom-right corners heavily to handle the diagonal mode. And line the walls there with absorbtion.

If I had to buy a few more tri-traps or mondo-traps, I could.

Thanks again.

[Ethan Winer]

Tom,

> The glass side is not all glass <

I don't think that matters much anyway. Glass and sheet rock both reflect. Glass reflects more at the highest frequencies, but this is still infinitely better than having a wall on one side only! More to the point, if you treat the first reflection points equally on both sides, any disparity will matter even less.

--Ethan

[majortom]

Thanks guys.

[bpape]

I'd agree. Treating the reflections at both sides equally will help quite a bit to even things out. My comments were more about the plywood not helping much.

Either position can be made to work for you.

Bryan