Square-shaped, Low Ceiling, Concrete Basement Room

Hi to all once again, I'm planning to turn one basement room (630x605x230cm) in house of my old folks to project studio. It will be used for composing/producing electronic and pop music using software DAW and VST's mostly, occasionally with live voice or instrument (e.g. guitar) and none of live drums. So, it won't be particularly loud, shouldn't exceed often 100-105 db, I suppose. But, there will be a lot of low frequencies from synth bass and kick drum that I would hope to isolate from rest of the building (upstairs is old folk's living room). Neighborhood is quiet, but there is a road near basement's windows also. Not much traffic do. 3 walls are outer walls made of reinforced concrete 25cm thick. The wall with room entry is made of 25cm wide concrete blocks. Behind outer walls is ground- rocks and dirt. Ceiling: concrete slab 18 cm tick. Upstairs is a living room with floor well isolated: 5cm of Styrofoam, on top of it 5cm of screed and then parquet. Floor: concrete slab 10 cm tick. Underneath is rocky material. Q no.1: Should I a.) keep rectangular, but shrink room to more acceptable ratio, and if so, which one due to such low ceiling (obviously not one of Louden's 1:1.4:1.9 likes, because I would be left with volume of a broom storage) b.) go octagonal. If so, can someone give an idea about a shape or at least orientation (regarding doors and windows)? c.) leave it as it is, just fill it up with with traps and various absorbers and buil a Helmholtz absorber tuned at one or several frequencies (in that case, which frequencies?) Q no.2: What with floor and ceiling? Again, there is already not enough space in between at first place. Regarding ceiling, would it be enough to cover it in mineral wool e.g. Rockwool Steprock or even Rockwool Conlit? That would be 5cm thick. Should I double it? Should I leave cavity 3-5cm between isolation and ceiling? Regarding floor I don't even have an idea. Can I leave it as it is (with coating of hydro-isolation of course)? Budget: Can all of that be done south of 3-4k USD? I would appreciate ANY help and suggestion.

Here is my biggest dilemma, shrinking room to 1:2,4:1,6 or build octagonal room inside. And what to use drywall or concrete blocks?

Hi shomium, and welcome! From what you say, this is just going to be a control room, right? No other rooms involved?

3 walls are outer walls made of reinforced concrete 25cm thick.

Excellent! You already have a great outer leaf for your isolation.

Behind outer walls is ground- rocks and dirt.

Even better! Not only do you have a massive outer leaf, you also have excellent damping on it. Your isolation is practically done already.

Ceiling: concrete slab 18 cm tick. .... Floor: concrete slab 10 cm tick. Underneath is rocky material.

OK, that's enough! Stop! You are making me jealous already! :) Seriously, you have a great structure around you. The only issue is the height, but it's not too bad, actually.

keep rectangular, but shrink room to more acceptable ratio,

It isn't necessary to go crazy about getting a great ratio. Ratios are more like guidelines: Stay away from teh bad ratios, get close to one of the good ones, and that's fine. In your case, you could probably make the room a bit narrower to even out the modal spread, but you are going to lose a few cm on each side with the inner leaf construction anyway, so the ratio should improve. But you have plenty of room volume: almost twice the minimum recommendation (45 m2), so there's not too much of a problem there: you can sacrifice a bit of space if you need to, but try to keep the height as much as possible.

go octagonal.

Personally, I do not like that shape at all. Not sure where it first came from, or why people keep recommending it, but it actually doesn't make much sense at all, acoustically, as the shape for an inner leaf. It cuts off the rear corners, which is precisely where bass traps are most effective, and also cuts off the front corners, which is you need in order to soffit mount your speakers! So as the final shape for the VISIBLE inner surface of a room, it is fine, but as the shape for the inner leaf wall itself, it is just silly and pointless. Yet, for some reason, it keeps on popping up as a suggestion! Go figure... Probably someone somewhere once saw a room with that shape from the inside, and the room sounded great, but the person never realized that most of the surface he/she was seeing were just decoration, covering the treatment behind! They thought it was the shape of the room, not understanding that it was just the "shape" of the treatment. So that's my rant for today on why I wouldn't use the infamous "octagonal" design. However, I would consider perhaps splaying your side walls, since you have the room to do that, but I would NOT angle your ceiling, since it is already low. I'd just hang a hard-backed cloud instead.

leave it as it is, just fill it up with with traps and various absorbers and buil a Helmholtz absorber tuned at one or several frequencies (in that case, which frequencies?)

Not a good idea: your ratio at present isn't terrible, but also isn't good: it can certainly be improved. Try to keep as much height as possible, and just adjust the width and length (try not to change the length too much either). And tuning with Helmholtz resonators is a last resort: First tune with broadband, then tweak with more specific things, like slot walls, panel traps, etc. And only then resort to highly tuned narrow Q Helmholtz resonators if you really need them to tame something drastic.

What with floor and ceiling? Again, there is already not enough space in between at first place.

Floor: Leave it as plain concrete! It's great, acoustically. You can stain it artistically, to make it look nice. Or if it is too ugly for that, then lay laminate flooring. Including the underlay, it will only take up around 1cm or even less. Ceiling: First, how much isolation do you need, and how much do you already have? If you already have enough, then leave the ceiling as is. If not, then you'll need to sacrifice about 10 to 15 cm of height for that. But you need real numbers. Get a sound level meter to measure how loud you are, and how quiet you need to be. The difference is ow much isolation you need.

Regarding ceiling, would it be enough to cover it in mineral wool e.g. Rockwool Steprock or even Rockwool Conlit? That would be 5cm thick. Should I double it? Should I leave cavity 3-5cm between isolation and ceiling?

For isolation? No, that won't work. For treatment? Maybe, but it all depends.... :)

Budget: Can all of that be done south of 3-4k USD?

Very tight. If you leave out the floor and just keep bare concrete, and don't need to isolate the ceiling, then you might be OK. But if you need to do floor and ceiling, plus treatment, then that might not be enough. So your first step, before deciding on the ceiling, is to do some real tests with a sound level meter and full-range speakers, to see how much more isolation you need, and at what frequencies: Based on that we can help you decide what type of isolation you need (if any), which also dictates the type of construction that you will need. And based on that final ceiling height, you can figure out the best ratios, which will determine the other dimensions of the room, the shape, the first round of treatment, etc. Once you get your numbers in order, the rest follows easily. - Stuart -

Stuart, thank you on your reply. I played a bit with John's design of a Small Studio and derived with this drawing. I thought of using metal studs. What is better for soffit construction: metal or wooden studs? What can I do with spaces A and B?

Would be an overkill if I put both hangers and superchunks in? (If yes, which to keep?) To keep symmetry, I left a space on the right side of the room and on the practical side, I could throw amp's rack in.. Is that a good idea?

Till I'm waiting for some comments on combination of superchunks and hangers in the same corner, here is one more variant of a same concept, now with slat resonators on side walls.