John Sayers' Recording Studio Design Forum

Greetings folks,

I've been lurking for some time and have had questions, but was far from being in a position to take action, so I thought I'd spare the community thrash

So after years of having a completely terrible location for my mixing desk, I have secured space to relocate my console. To start my project studio was intended just for personal projects such as a loud rock band and the noise floor was never really the biggest issue since we've never needed to deal with real nuance. That being said, to give an idea of what I've been doing, I've been multi-tracking all the practice sessions of the band using an O2R and and a focusrite octopre to give me 24tracks -> RME adat interface; monitoring with Yamaha MSP10's/w sub. I use mostly dynamic mics for the cabs and drums with the exception of dropping some octava 012's for overhead. I understand I could do alot with better mics but also fear that the additional detail will make my room flaws quite pronounced. The room where the sound sources are located is ~75' north of the north wall of the room and is well separated and I've not heard bleed in my old control room which was in the adjacent (12' square room yuck).

I have a new space to work with. I have been trying for some time to educate myself above noob in the subject, but do not feel confident to make a call on whether I should seperate my control room from the larger new space with a target dimensional ratio very near to 1:1.4:1.9 as I've seen noted many times. As luck would have it, my (H) and (w) are very close proportionally to 1:1.4; actually 1:1.39. Although my first inclination was to install a north wall (and door) such that the ratio conformed closely at 1:1.39:1.9. I included my excel matrix where I was attempting to resolve the appropriate (l) distance. I was concerned about the overall volume (ft^3) of the room.

Some notes in hopes that I can make this case coherent...

Room:

10.5' width
7.54' height
24' length (max)

Walls:

All painfully parallel

S.Wall: 5/8" gypsom over studs attached to concrete, rubber barrier material between contact points, voids insulated with OC fiberglass batting.

E.Wall: 5/8" gypsom over studs attached to concrete, rubber barrier material between contact points, voids insulated with OC fiberglass batting.

W.Wall: 5/8" gypsom over studs, modified home construction, added high density insulation to all voids

Ceiling: 5/8" gypsom over studs, modified home construction, added high density insulation to all voids

North Side: Closet, drywall, standard home construction


The big question for me is:

Would seperating the control space from the larger room area with a wall that yields proportions of very close to 1:1.4:1.9, given the overall volume of the room, introduce more problems that I'd have to attenuate that just leaving it alone and treating the default negative effects?

I fully expect that I'll be attempting to address bass summing in either case, but certainly didn't want to do something that may be counter productive. I've set aside another 800-1000usd for wall construction, but had wondered if not doing a wall and perhaps a heavy north curtain to ease rear HF reflection and allow for a small sitting area in the north side. Those funds if a wall wasn't warranted, would purchase a considerable amount of sound treatment materials.

Thank-you for whatever advice you can spare. Hopefully it's actionable for me. As I had mentioned, feel like I'm playing with fire and I should get some alignment to best practices

/cheers

Malcolm
Vancouver, WA NW-USA

Hi Malcolm, and Welcome!

Questions are good! As one of my high school teachers used to say (way back when, in centuries past... ) "The only dumb question is the one you didn't ask". So feel free to ask.

Just a few random comments on your post:

Not so good just like that! The ratio is way out there, beyond the ball park. Way too long for the height and width.

However, from the next part of your post (about the construction materials) it seems that you the above numbers refer to the dimensions of your OUTER leaf, not your INNER leaf. It's the inner leaf that matters: You should calculate the ratio using the dimensions for the room surfaces that you will see as you stand inside it, after you put up all the walls, but before you put in any treatment.

So you need to figure in that you'll be losing around 6 inches off each wall and the ceiling, then re-figure your ratio based on that.

But even then, the room is going to be way too long and narrow to be able to get a good ratio. If that were my room, I'd split it, and use the other part for either a small live room, a vocal booth, or storage.

That's Louden's first ratio, yes, and it is a good on, but there are many other good ones. Just to name a few Sepmeyer, Bolt, and Boner all discovered good ratios, some even better than the one you mention, .... But NONE of them are out in the 1 : x : 3.18 region (where your 24 foot length is)! That's off the charts. So it makes sense to split the room.

The idea with ratios is not to go crazy, looking for the non-existent "perfect" ratio: there is no such thing. Just stay away from the bad ones, get close to a good one, and that's all you need to worry about. No need to go overboard.

It would solve problems, not create them! Yes, you have a large volume with those dimensions, but you also have an impractical room without a usable ratio. It fails two of the three critical tests used by the BBC for deciding on rooms.

If you cut the room length down to 14.3', then you have a MUCH better modal situation. It now passes all 3 BBC tests, the Bonello chart looks smooth, and overall things look a lot better, and you still have a total volume of over 1100 ft3. A bit short of the ITU recommendation, but still reasonable.

Not quite sure what you mean by "bass summing", but if you are referring to the modal behavior of the room, then yes, you'll always have that. Ratios don't get rid of modes: they just spread the around evenly, which is the best you can hope for. There is no way of getting rid of modes: they are a fact of life, directly related to the walls around your room. If you don't want ANY modal problems at all, the set up your equipment on a table in the center of an empty field, with nothing at all around you in a radius of about a hundred feet! That's the only way to have no modes. As soon as you put walls around the room, you have modes, and you cannot make them go away. You can just choose the dimensions wisely to minimize their effects. And yes, the problems for a small room will ALWAYS be in the low end.



OK, now about your construction plans:

Skip the "rubber barrier material between contact points", since there will be no "contact points"! If you want to isolate your room (sometimes incorrectly called "soundproofing"), then the new walls you build (your "inner-leaf" walls) cannot, must not, will not, and shall not touch any part of the existing structure, except the floor. The walls sit on the floor (which I'm assuming is a concrete slab in your case), and they ONLY touch each other: They do not touch the existing walls or the existing ceiling (the joists and sub-floor above you). If they did touch, then that would severely compromise your isolation, as they would pass the vibration right through to the rest of the building.

So build your stud frames to sit on the floor, braced against each other, and the same applies to your new ceiling: put new joists across the top of your new wall frames, and do not let those touch the ceiling above or the existing walls. This is a totally separate, decoupled structure you are building, and it cannot have any direct mechanical contact with the existing structure.

Yes, you do need to fill the cavity with insulation, and yes you do need 5/8" drywall (fire-rated).

What do you mean by "modified home construction"??? As I mentioned above, the way to do your new ceiling is simply with joists that rest ONLY on your new inner-leaf walls, and drywall hung from that.

Also, high density insulation is a bad idea. It will give you WORSE performance for bass frequencies than the correct density. Contrary to popular belief, higher density insulation does NOT improve bass absorption, and in fact harms it! If you want good bass absorption, then you should use lower density insulation, not higher density.

In fact, it isn't even the density as such that matters: It is gas flow resistivity, which is the technical name for the acoustic property of fibrous open-cell materials that tell you how it deals with sound waves moving through it. It turns out that there is a very rough, approximate and non-linear relationship between density and gas flow resistivity, but it varies for each TYPE of insulation. So if you plan to use mineral wool insulation, then need a density or around 50 kg/m3, and if you are gong to use fiberglass insulation then you need a density of around 30 kg/m3.

So when you build those walls, make sure that the studs only touch the floor, nothing else, and when you put the insulation in, make sure it is the right type and density.


- Stuart -

_________________
I want this studio to amaze people. "That'll do" doesn't amaze people.

Stuart, thanks kindly for the advice. It will help my decisions considerably