Studio Design Concept - Feedback please?

[macgregor]

Hi,
I was wondering if you could yay or nay this design concept for a studio in my back garden.

I'm converting an outbuilding space into a studio. The interior dimensions are approximately 8m by 10m. (I'll be able to get exact dimensions next week). The shell is of breezeblock construction.
I plan to split it 50 : 50 into a control room, live room each being around 5m by 10m before modifications.

Being on a budget (around 2000 probably, though subject to change-i'm just designing, the wallet owner hasn't given me a a definite figure)
All construction will be by myself and a friend.

The walls will be a DIY version of the fabric wall system - plasterboard backplate with a wooden frame and 100mm rockwool with fabric stretched over it.
The ceiling will be a false ceiling of the same design, hung from the existing ceiling.

Control Room:
The front wall will be have a 1.5m by 0.5m (ish) window through to the live room. The seperating wall will be breezeblock, with the above mentioned fabric walls mounted in front of this with a gap between them and the breezeblocks.
The "false" fabricwall side walls will each be at a 5 degree angle off the existing breezeblock wall, resulting in the narrower end being the end with the monitors and the wide end the back of the studio.
The rear wall is just flat.
In each corner there is another panel to soften the corners from 90 degrees to two lesser angles.
The ceiling is flat at the front of the room, then just before where the monitors will stand it will begin to slope up at an 8 degree angle

Live room:
Basically rectangular, with the fabric walls, then air space, then the outer breezeblocks like in the control room.
Again, each corner is panneled so not 90 degrees.
in the front corner to the right of the window is a cupboard for recording amps.
Flat ceiling.

Door: For the live room - control room adjoining door I'm thinking of using fire doors with seals round the edges.
Window: Three layers of glass with air gaps of a couple of inches between each one.
Floors: The existing floor is uneven concrete. I will lay 'studwork' across this, then chipboard, then carpet tiles.

Equipment:
I will be largely in the box to start with, but am anticipating adding in outboard gear later on.
So yosemite running lpx, 16 i/o interface (possibly motu, still yet to be bought)
mackie 32 8 (possibly)
monitoring on adam a7x, speaker stands a meter and a bit off the front wall

And a sofa at the back because... sofa.

I'll be installing xlr wallplates in the live room, with the the cables leading through the wall cavities then back to the control room.
Lighting is as of yet undecided. Not bloody strip lighting though.

So what do you think of the overall design concept?
A couple of main things on my mind:
Do i need to have two doors from between the live and controll rooms? (control room - void then void - live room) or will one be sufficient?
Is the sloped ceiling in the control room necessary or a waste of time?
Will 100mm of high density rockwool be sufficient at adsorbing sound or will i need additional room treatment?

Thanks in advance for any help,
I have attached screenshots from a very quick first sketch design.

Mac

[Soundman2020]

Hi Mac, and Welcome!!!

I was wondering if you could yay or nay this design concept for a studio in my back garden

"Nay"! Or mabe "Yay", but with caveats. (actually, it's not as bad as I'm making it sound...)

The interior dimensions are approximately 8m by 10m.

Nice. A decent size. But you didn't mention the height: Sound is 3D, so it is also very necessary to take the vertical dimension into account.

I plan to split it 50 : 50 into a control room, live room each being around 5m by 10m before modifications.

That would be the first bad idea. That would create serious modal issues, and they would be identical in both rooms! Not a happy situation. Since 10m is exactly twice 5m, all of the first order modes in one axis will fall at the exact same frequency as the second order modes in the other axis...

You should take a look at "room ratios", and "room modes" and "modal spread", and similar concepts to get an idea of why this is bad, and how to improve on that in your design.

Second, the LR should be much bigger than the CR, in total volume. If not, you will never be able to hear the LR signature tails in the CR, because they will be masked by the CR's own decay.

Being on a budget (around 2000 probably, though subject to change-i'm just designing, the wallet owner hasn't given me a a definite figure) All construction will be by myself and a friend.

Not want you want to hear, but your budget is unrealistic. It needs some serious rethinking. You are saying that you have 80 square meters, and you only want to spend 25 per square meter to build this... just the HVAC system alone will blow your budget right out of the water (yes, you DO need one...)

The walls will be a DIY version of the fabric wall system - plasterboard backplate with a wooden frame and 100mm rockwool with fabric stretched over it.

Sorry, but that would be another major mistake: that offers no isolation at all. It will also completely kill the room acoustically, so you will need mostly reflective treatment to get the life back into it.

The ceiling will be a false ceiling of the same design, hung from the existing ceiling.

Ditto.

The front wall will be have a 1.5m by 0.5m (ish) window through to the live room.

2 panes of suitable laminated glass that size will set you back around £ 400. That's 20% of your entire budget...

The seperating wall will be breezeblock, with the above mentioned fabric walls mounted in front of this with a gap between them and the breezeblocks.

Why do you want a three-leaf wall? Are you aware that a three-leaf wall will always give you WORSE isolation than the equivalent two-leaf wall, all other factors being equal?

The "false" fabricwall side walls will each be at a 5 degree angle

Why 5°? That isn't even enough to deal with flutter echo! (you need at least 6° for that). And it certainly is not enough to produce a true RFZ.

The rear wall is just flat.

Why? How come there are is no bass trapping? It's a small room, so it ill need a LOT of bass trapping. And since the rear wall is always the most critical, that's where a large percentage of the bass trapping must be.

I'm not understanding the design concept here: Which philosophy is it based on? It isn't making much sense.

In each corner there is another panel to soften the corners from 90 degrees to two lesser angles.

Once again; Why? Why waste those prime positions for bass traps, and use them for ineffective reflections panels that won't actually do anything useful?

The ceiling is flat at the front of the room, then just before where the monitors will stand it will begin to slope up at an 8 degree angle

Here too, the same question: Why? What is the reasoning behind that? It makes no sense: it does not deal with the first reflection issue, and the 8° angle is insufficient to deal with even flutter echo (it would have to be at least 12° there). Is this ceiling layout something that is imposed by the existing building? If not, I can't see the reasoning for it at all.

Basically rectangular, with the fabric walls, then air space, then the outer breezeblocks like in the control room.

A "farbic wall" is not a wall at all. There is only one basic way to stop sound, and that is with mass. Lots of it. The amount of mass (surface density) is determined by the equations for MSM resonance, based on the amount of isolation that you need, and the frequency that you need it at. Fabric has basically zero mass. Your walls need substantial mass.

Again, each corner is panneled so not 90 degrees.

Again: why? What purpose do those panels serve? And why waste that space? Corners are so very useful, acoustically, that it seems strange to just put decorative panels in them.

Door: For the live room - control room adjoining door I'm thinking of using fire doors with seals round the edges.

That would be a good choice, yes. You need at least two independent seals around each door. Those doors go for around £ 350 each. You need four of them. Total of £ 1,400.

Window: Three layers of glass with air gaps of a couple of inches between each one.

A triple leaf window? Once again: WHY? Why would you want to do that when you will need thicker more expensive glass, due to the triple-leaf effect and the very thin air cavities? Why would you not go for the far more effective two-leaf window, so you can have on single very deep cavity, and thus be able to use thinner, less expensive glass? I'm really not following the design philosophy at all...

I already mentioned that two panes of suitable laminated glass that size will set you back around £ 400. Three panes of thicker glass will set you back around £ 700 to £ 800.

Floors: The existing floor is uneven concrete. I will lay 'studwork' across this, then chipboard, then carpet tiles.

... and that would trash the room acoustics! There's a reason why you practically never see carpeting in professional studios... it does the exactly opposite of what is needed, especially in small rooms. Just level your floor with a few bags of self-leveling cement. Cheaper, far more effective, wastes less headroom, and it gives you the perfect surface for your studio floor.

monitoring on adam a7x,

Nice!

speaker stands a meter and a bit off the front wall

... which would give you a huge SBIR dip in your frequency response at around 180 Hz! Why do you want to set up your speakers in such a bad location? The room is not big enough to be able to get the speakers sufficiently far away from the walls, so the ONLY possibility is to put the, right up against the wall, such that the SBIR artifacts are pushed up into the mid-range, where the are not so objectionable.

So what do you think of the overall design concept?

The CR is set up sideways! It's a decent size, but being a small room, the speakers do need to fire down the longest axis o the room, not across the short dimension. The way you have it now, your head has to be in the exact geometric center of the room, which is the worst possible position in the entire room! Rotate your room 90° left, so that it is facing the wall at the top of the page, re-arrange the layout and geometry with the speakers 10cm off the front wall, about 117cm form the side walls (meaning that they will be about 186cm apart), then set up the mix position at 290 cm from the front wall, and with the acoustic axis 1.2m above the floor. Angle the speakers inwards so that they are pointing at a spot about 30cm behind the mix position. Now you have the roughly correct basic geometry for that room. Speakers should not ever be tilted up or down: keep them flat.

Place treatment at the first reflection points, superchunk style bass traps in all the corners, thick absorption across the entire rear wall, and you have your basic treatment. An angled, hard-backed cloud will finish off the room nicely, along with a couple of suitably sized and placed absorption panels.

Do i need to have two doors from between the live and controll rooms?

Yes. You need one door in each leaf. The same applies to your entrance door: two doors, back to back, one in each leaf.

Is the sloped ceiling in the control room necessary or a waste of time?

If done correctly, and if you have the space and budget to do it, it is not a waste of time. If the ceiling is low, or it you don't know how to do it, then an angled hard-backed cloud is a good substitute (provided that it is designed correctly, built correctly, positioned correctly, and angled correctly....)

Will 100mm of high density rockwool be sufficient at adsorbing sound or will i need additional room treatment?

Sufficient for what? Porous insulation does not adsorb sound: it absorbs it. That's why it is sometimes referred to as "porous absorption". 100mm of high density rockwool around the room will certainly absorb practically all of your high end, most of your mid range, and some of your low end too, but it won't do much for the bass, since it is too dense for that. This treatment plan would leave the room sounding very dull, lifeless, "thuddy", like the interior of a very thick pillow. If that's the sound you are looking for, then it will work. However, the normal condition for a successful control room is to have neutral frequency response within +/- 3 dB from 250 Hz to 2 kHz with slight roll-off permitted at each end (2 dB per octave), which is similar to the curves described in the AES, EBU, ITU, and other specs, and time-domain response in accordance with the total room volume, not varying by more than 50 milliseconds between adjacent 1/3 octave bands across the spectrum, except for an allowed 300 ms rise in the bass end (below 200 Hz), and an allowed (and recommended) 100 ms roll-off in the very high end (above 4 kHz). That's the spec that control rooms should aim for. 100mm of high density rockwool all around the room will not get you anywhere close to that.

So your basic building has promise, but you'll need to do some work on the isolation plan, the layout, the acoustic design and treatment plan, and most of all, the budget.

- Stuart -