Any potential problems here?

Hello, I'm an audio engineer in Sydney, currently working near the city (a bit of a drive for me), and have recently started the planning stages for moving my operation closer to home. Across the driveway, actually, in some planned new construction above the brick garage. After what feels like way too many hours in Sketchup, I've come to a design that I think could work well, given the constraints in place. What this ideally ends up as is a nice neutral sounding control room, mainly for mixing, with some "on the cheap" mastering, plus a decent sounding performance/live room area. I do like to listen at higher volumes (eg. 110 dB) occasionally, though normal working volume is more like 80-ish, and would love to be able to track the odd drum kit if the need arises. I don't want to get fanatical about isolation though, as the closest neighbor's house is maybe 100m away, and as I'll be the only engineer working here, timing my loud hours will be easy enough. The main constraint with the proposed space is the placement of the stairs. Other factors (SWMBO, storage issues, etc.) dictate that the only real option is where I've put them in the plan. My current idea is to use a "trapdoor" type entry, to maximize floor space and cut costs. Speaking of costs, ideally the budget needs to come in under AU$20,000 for the interior stuff. Exterior construction will be semi-expensive, as we live in a "flame zone", so wood is out. Talking with my builder, we're currently considering compressed fibre cement sheeting or Hebel. Happy to be pointed to other better or more cost-effective options. Other things to be included that don't appear in the .skp: *A toilet and sink, in a smallish space that is asymmetrical and fully tiled, which can double as an echo chamber of sorts (I love real room ambience). Intended spot is indicated. *A window (or 2 even!) to the outside world - I love natural light, but I suppose it's a tradeoff between isolation and cost. *I'll probably end up with a wall mounted split system unit or 2 for aircon, but that needn't be included in the budget above. *Lighting I can get for next to nothing, so that should also be excluded. *I do not want to float the floor. :) Anyway, that's about all I can think of for now. I would love to get some general feedback on the preliminary design (I have a more detailed .skp with the garage below that I can also make available if necessary). In particular, I'd like to be made aware of any problems that I may have overlooked. Measure twice, cut once, and all that. Thanks for looking! Cheers, -Andrew Beck Sketchup file is here. 1.8MB p.s. I haven't started on the live room yet. Wanted to get the control room sorted first.

welcome! what type of roof shape do you have? why not make a nice rectangular room sitting sideways with the sliding doors looking across into the other space? then angle the treatments etc. this way if you need a larger space for the drums etc it might be the remaining space over the garage could be better suited for getting a decent drum sound without impacting the control / mastering room acoustics?

Hi Glenn, thanks for responding... Okay, roof shape. The plan is just a simple "slab" roof, corrugated Colourbond on the outside, finished on the inside (probably with gyprock, but TBD). As to the rectangle, I did initially start there, but couldn't find a rectangular shape/size that was both a good ratio and working well with the stairs. Also, I've worked in many "real" rooms over the years (cut my teeth as an intern at Bad Animals in Seattle, then lived/worked in L.A. for several years before moving here), and none of them have ever been rectangular. I've also had to work in some shoebox-shaped spaces, none of which were anything to write home about, acoustically. The current design started as a 1:1.6:2.33 "cross" of guidelines at a 45 degree angle, and the shape grew from there. It's got plenty of room for absorption and/or storage space between the interior and exterior walls, which is a plus. Also 5.5m x ~7m is more than I need for a drum area. I'm willing to be convinced if a rectangular space really would be better though! Full disclosure: It's likely that I'll get an acoustician involved at some point as well, though I'd really like to have firm ideas about what I need versus what will work within the confines of the proposed space before I do that. Thanks, -Andrew

The current design started as a 1:1.6:2.33 "cross" of guidelines at a 45 degree angle, and the shape grew from there.

Well, for that shape of room, ratios are pretty meaningless. Ratios only work accurately for purely rectangular rooms. For any other shape, especially one with unusual numbers of walls, you cannot use normal room rations and normal mode calculation tools to predict what the behavior will be. Once you get away from rectangular, then prediction becomes vastly more complex, and you really need FEA tools to figure things out. Of course, that may or may not be an issue: For rooms only a bit off rectangular, the predictions probably won't be too far off either, and for any room you still need to measure it once the inner leaf is finished, to find out what it is ACTUALLY doing, as compared to what theory PREDICTED it would be doing, and only then should you make the final decision on treatment. But your room shape is so far off rectangular that it doesn't seem reasonable to be talking about ratios for it. For a start, it doesn't even have the usual 6 sides, but rather seems to have TEN sides! :shock: You also seem to have a lot of wasted space, which could be better used as part of the room, with a bit of fiddling. I agree with Glenn: you can probably do better than that with a a rectangular room, or a near-rectangular room. Even one with the basic simply splaying for RFZ is close enough to rectangular that ratios and prediction tools will at least give you an idea. It would be easier (and cheaper) to build and easier to treat, too. - Stuart -

Soundman2020 wrote:

But your room shape is so far off rectangular that it doesn't seem reasonable to be talking about ratios for it. For a start, it doesn't even have the usual 6 sides, but rather seems to have TEN sides! :shock: You also seem to have a lot of wasted space, which could be better used as part of the room, with a bit of fiddling. I agree with Glenn: you can probably do better than that with a a rectangular room, or a near-rectangular room. Even one with the basic simply splaying for RFZ is close enough to rectangular that ratios and prediction tools will at least give you an idea. It would be easier (and cheaper) to build and easier to treat, too. - Stuart -

Well, to be fair, it's got 8 sides (really 7, as I'd assumed the "wall" across the back corner would be a bass trap, not a wall), and I really wasn't talking about ratios for it, just stating how I got to where it is, but I take your point. Too complicated, okay. I'll go back to the drawing board and see what I can come up with. Thank you, -Andrew

Well, to be fair, it's got 8 sides (really 7, as I'd assumed the "wall" across the back corner would be a bass trap, not a wall),

And the floor? And the ceiling? They count as "sides" to the room, acoustically... :) - Stuart -