New flat - room acoustics questions

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Arneb
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New flat - room acoustics questions

Post by Arneb » Fri Feb 07, 2020 4:33 pm

Hi all,

we're moving into a new flat and, being wigglers and all, we're thinking about acoustics of our new living and music making room before buying, I dunno, a couch and a table. Unfortunately I'm a complete newbie on this stuff.

I've made a couple sketches using SweetHome3D:
livingroom1.png
livingroom1.png (375.66 KiB) Viewed 192 times
livingroom2.png
livingroom2.png (53.38 KiB) Viewed 192 times
Details:
- The room is pretty exactly 6m on the sloped side, 5m on the straight side, and a measly 2.2m high.
- The slope is about 30° and starts at 1.1m height.
- The placement of the windows isn't exact, they've just been mounted and I haven't been able to take measures yet, but you get the idea.
- The two outer walls (the brickwalls with the windows) are pretty well insulated, and the windows themselves are state of the art. The inner walls (the white ones), OTOH, are double slabs of drywall.
- The straight part of the ceiling is drywall covering massive wooden beams. I haven't measured the spacing of the beams.
- Power outlets are not a concern.

Our current speakers are shit - some Logitech speakers left over from my gamer days. Which is why I'm planning to buy real near-field monitors for the new apartment. I haven't decided anything yet but am currently leaning towards a pair of Yamaha HS8s.

Now according to what little I know about room acoustics, there's a whole lot of unpleasant compromises involved in actually placing monitors there.

There's no "real" wall which doesn't have windows. Mounting them on the sloped ceiling parts, centrally, in equilateral triangle configuration won't be possible because that's where the roof windows are (or at least I think so). On the straight reinforced wall there's no "central" point because of the slope, and also the window is in the way. Mounting anything heavier than a canvas painting on the two other walls isn't going to happen. Ceiling mounting might work, but will be tricky. Well, and placing everything in the middle of the room won't fly because it's still supposed to be a living room...

What I could find about room acoustics for beginners just tell me that I should avoid sloped ceilings, but aren't really specific on what to do when you're SOL there.

There's also the question of how to place bass traps, diffusors etc to consider. Plus a couch and table, some shelves, a dining table, and possibly a DIYed 19'' rack.

So... well, what would you guys do?

Technologear?
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Re: New flat - room acoustics questions

Post by Technologear? » Tue Feb 11, 2020 6:32 pm

Before you move in, do the boring but practical stuff of room treatment. I like the goal of 'totally dead' as that's basically practically impossible in a residential space. I'd target the floor first as it'll especially cop the angled ceiling reflections. I'd go green glue under the thickest carpet you can afford with the thickest rugs you can afford on top of that. If you can't install carpet, thick rugs with doubled carpet underlay cut to size underneath. I'd put most of my budget on this part.

Ceiling treatment next: your flat ceiling likely too low so focus on the 3 spaces between the angled roof windows.
Something that absorbs as much as possible, within the constraints of mounting load due to weight. Likely some ceiling beams in there to attach to. I'd find a local carpenter to make some frames to size that you fill with fluffy (high absorbing coefficient insulation) and cover with thin material. Mounted with an inch or 2 space from the ceiling so anything that gets though bounces back through it again to get absorbed.

Anything left in the budget, design some absorbing mass in the bottom corner of the sloped ceiling. You won't be using the space anyway. Some panels made by the carpenter like the ceiling ones along the internal dry wall would be pushing it too far I'm assuming.

I wouldn't worry about anything else after this like speaker placement etc. It's a living space, just make it as comfortable as possible for chilling that then fosters wiggling. Comfy thick couch for more absorbing, let your significant other choose where everything is placed. With established room treatment already it'll be good enough.

Arneb
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Re: New flat - room acoustics questions

Post by Arneb » Wed Feb 12, 2020 8:08 am

Thanks a lot, you're giving me a lot to think about there!
Technologear? wrote:
Tue Feb 11, 2020 6:32 pm
Before you move in, do the boring but practical stuff of room treatment. I like the goal of 'totally dead' as that's basically practically impossible in a residential space. I'd target the floor first as it'll especially cop the angled ceiling reflections. I'd go green glue under the thickest carpet you can afford with the thickest rugs you can afford on top of that. If you can't install carpet, thick rugs with doubled carpet underlay cut to size underneath. I'd put most of my budget on this part.
I'm afraid I won't get my SO to agree with that :'( basically, she hates the idea of a bright carpet because it gets ruined the first time someone trips with a wine glass, and dark carpet would make the room feel even lower than it already is. I'll have to look into other options for damping reflections from the floor.
Ceiling treatment next: your flat ceiling likely too low so focus on the 3 spaces between the angled roof windows.
Something that absorbs as much as possible, within the constraints of mounting load due to weight. Likely some ceiling beams in there to attach to. I'd find a local carpenter to make some frames to size that you fill with fluffy (high absorbing coefficient insulation) and cover with thin material. Mounted with an inch or 2 space from the ceiling so anything that gets though bounces back through it again to get absorbed.

Anything left in the budget, design some absorbing mass in the bottom corner of the sloped ceiling. You won't be using the space anyway. Some panels made by the carpenter like the ceiling ones along the internal dry wall would be pushing it too far I'm assuming.
The sloped ceiling and bottom corner are fairly well insulated, actually - they're outer walls with brand new insulation. In my country (Germany) AC never became popular in private homes and the government incentivizes insulating everything to death to cut down on heating-related emissions. The question here would be how good this thermal insulation stuff (glass wool, IIRC) is at damping sound.

Arneb
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Re: New flat - room acoustics questions

Post by Arneb » Wed Feb 12, 2020 2:06 pm

Addendum on the floor issues, does impact noise insulation play a role here? The laminate flooring isn't installed yet, so the impact noise insulation quality is a free parameter so far.

Technologear?
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Re: New flat - room acoustics questions

Post by Technologear? » Sat Feb 15, 2020 4:34 pm

SO is the barrier, sorry mate.

Sound transference through the structure (that annoys neighbours) isn't what you're focussed on, you want sound diffusion and reduced reflections. The ceiling and floor insulation you note functions like the sides of a pinball machine - keeps the balls inside to annoy you! You want to reduce how much those balls bang and clash around inside the machine, by hitting into absorbant material wherever they might go, to slow them down. That's what my suggestions were targeting.

Laminate flooring is very reflective. As are flat walls and ceilings. Like the bumpers and flippers in a pinball machine.

Arneb
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Re: New flat - room acoustics questions

Post by Arneb » Sun Feb 16, 2020 9:20 am

Alright, I see, thanks a lot... so, best bet would probably be that treatment of the sloped ceiling and low corner you're proposing, plus some rugs behind my playing position, with the monitors mounted to the sloped ceiling as to minimize sound volume in direction of the flat ceiling? (Rugs are negotiable because you can at least remove them for cleaning)

Technologear?
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Re: New flat - room acoustics questions

Post by Technologear? » Mon Feb 17, 2020 8:41 am

I'd position the monitors so they are aiming at the most absorbant or refractive (not flat) surface, with the listening position in between.

Positioned under the angled roof windows, they are aiming at that flat highly reflective wall. I'd prefer them along the flat wall, facing the angled ceiling, that had sound absorption panels attached to it, and thick rugs on the ground underneath.

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BailyDread
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Re: New flat - room acoustics questions

Post by BailyDread » Mon Feb 17, 2020 5:30 pm

just my two cents, i think the poster who advised aiming the speakers against the angled wall has the right idea... you want to make sure your listening position is more or less symmetrical. Personally, I'd probably put the desk up against the wall with the angle.

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