Would love some feedback on treatment design.
My goal for the control room is to have it equal parts critical listening, but also leaving a portion of the room a little lively for acoustic guitars of vocals.
It's fine (and doable) to have a CR that serves dual purposes, but that should not get in the way of the
primary purpose of the room: It's a control room, after all. So that's what it should be, first and foremost! You also want to use for acoustic recording, so that's the secondary purpose, ut it should not get in the way of the room being as good as it can be for mixing. Thus, it should be set up as a control room, to do that job well, then also have some "stuff" that can be added/changed on-the-fly as needed to do the recording.
If you try to design a room to do both at once, you'll end up with a room that does neither well. Make it one or the other, then adapt as needed.
So, your goal should be to have your bass trapping where it is most needed, and where it can be most effective, which is in the rear of the room (behind your head as you sit at the mix position). The soffits should also be built as proper soffits, that do the job they are supposed to do. What soffits are "supposed to do", is multi-fold. BUt the most basic thing they do, is to extend the front baffle of the speaker outwards to much larger dimensions, which achieves most of "what a soffit is supposed to do". Is solves the front wall SBIR problem to a large degree, it solves the power imbalance issue, it solves the edge diffraction issue, it improves focus, tightens the sweet spot, extends the bass response, and pretty much is the best possible thing you can do for your room and your speakers, in pretty much any room, and for pretty much any speaker (with some exceptions, of course). A "soft" soffit cannot achieve most of that. It can help a little, yes, but it doesn't do the job that a soffit can do, when built right.
This implies that the soffit face must be solid, hard, massive, rigid, and extend outward around each speaker for as far as possible.
So in this mock, I have treated the front half with deep corner traps, and a nice soffit trap that goes all the way around the room.
Putting corner traps in as many corners as possible, is a good thing! Absolutely! But corner traps in the front corners of the room are less effective than traps in the rear corners.
Basically, when designing the room treatment, take the point of view of the speakers: Think about what you would "see" of the room, if your head were in the location and orientation of the speaker. What you see there, is where your first priority of treatment should be, because that's the first things your sound waves are going to hit. And what you see mostly from that perspective, is the rear wall, the side walls, and part of the ceiling. Since all of those surfaces are going to be the first ones to get hit by sound waves, and your goal is to achieve the "20-20 criteria", then those surfaces should be treated accordingly: Major absorption to "suck up" as much of possible of the unwanted energy that could reflect of those surfaces back to the mix position, combined with secondary treatment to prevent the primary treatment from doing the task too well and over-absorbing some frequencies, and perhaps tertiary treatment to provide a bit of diffusion, if appropriate for the room (usually not feasible in small rooms: only medium and large rooms are real candidates for extensive diffusion).
Here, to, a proper soffit simplifies things: Your perspective as "my head is a speaker" is simpler if you don't have to worry about turning your eyes sideways, to figure out edge-diffraction, and don0't have to turn them around backwards, to figure our front-wall SBIR. With soffits, your full attention can be focused on your normal field of view, which is what the speaker "sees". The angle of view could change a bit, depending on the specific speaker you plan to use, and that will lead you in designing the most appropriate treatment for the side walls and ceiling. Some speakers have wider dispersion in certain frequency ranges, so consider that when you do this "my head is the speaker" trick.
This is a simple approach, but it will get you a long way to designing the most important treatment for the room.
If you do that, you'll find that you end up with a room that is mostly "hard" at the front (but with "soft" traps hidden inside, behind those hard front surfaces), and mostly "soft" at the back, with massive amounts of absorption (but tempered with some carefully placed and carefully targeted reflective surfaces, so as not to lose the high end, and keep things balanced.
The soffit is 12 inches tall, by 16 inches wide and will be stuff with rockwool.
I'm assuming that you mean the hard front baffle of the soffit? If so, that's rather small. I generally design soffits to run from floor to ceiling, with some open areas close to the floor and ceiling to expose the inner treatment to the room. So in a typical home studio conversion where the ceiling is at 8 feet, I'd leave a foot open near the floor and maybe two feet near the ceiling. Thus, the actually soffit baffle would be around 6 feet high.
Likewise in the horizontal direction: the general rule is that the soffit baffle should be at least three times the diameter of your low-frequency driver. So if you have a speaker with an 8" woofer, then you want the soffit baffle to be at least 24" (60cm) wide. Wider is better. An even more solid "rule of thumb" is simply that the baffle should be at least a 1/4 wavelength of the lowest frequency that the speaker will produce. That's hard to do in the majority of rooms! But it's a good goal to keep in mind, and will put at the forefront the basic need to make it as wide as you possibly can.
The ceiling cloud is about 8'x10' trapezoidal and will be 4" deep and 3" off the ceiling to account for LED lighting that I will be putting on top.
Clouds are good. Deep clouds are better. Angled clouds are better still (higher above your head, lower towards the speakers), and hard-backed clouds are even better yet! Shape isn't that important, so you can shape it any way you think looks good, but do make sure that it completely covers the first reflection points up there, and also covers the areas that could be sending too many unwanted reflections towards the back wall, side walls, or rear floor. This might help:
[url=https://digistar.cl/Forum/viewtopic.php?f=9&t=2&p=2Raytracing assistant for Sketchup, for visualizing speaker dispersion[/url]The 2x4 panels scattered throughout are 2" panels made with 703.
Are they strategically located at the first-reflection points for the mix position? Do they completely cover those points? Also, in general it's better to have treatment panels of differing depth and differing wall gaps, to avoid over-treating one specific frequency band. Many rooms end up with a "death valley" in their time-domain responses somewhere in the region of 150Hz to 500 Hz for this very reason: Overt-treatment with 4" deep traps. Make some of them 6" deep, or vary the air gap behind them, or angle them, or something! To make sure that you are not killing one part of the spectrum at the expense of another part.
am going in the right direction and how to keep the back of the room both controlling some of the bass modes and being a "alive" for vocals or acoustic guitars....
Everything I've said above is pretty much the opposite of what you'd need at the back of the room for acoustic tracking! Because it is what a Control Room needs, on order to function as a Control Room.
So what to do? The first thing you could do is to flip your tracking perspective! Since acoustic instruments sound better (and track better) with a bit of "life" in the room, then do the tracking towards the front of the room, where there is life. Since the entire front will be mostly reflective (large, solid, rigid, hard surfaces), you already have what you need up there: But mostly people do ti backwards! What's important here is what the
mic sees, not so much what
you see. So if you set up your acoustic guitarist facing the front of the room, with the mic in front of him facing the rear, then he will hear nice warm reflections coming back to his head from the front of the room, but the mic won't! The mic will be facing the totally dead rear wall. So angle your setup! Have the musician face one of the side walls, where there isn0t too much absorption, with his back facing another side wall, and the mic set up judiciously so it "sees" that side wall, and perhaps even some of the front of the room. Bingo! You get a better-sounding recording, and the musician also gets a decent sounding-room acoustic. It's not ideal, of course, but it can work. Experiment to find the best locations, orientations, and mic setups. This also applies to vocals and other acoustic instruments too: If you play around a bit with different spots / mics / angles, you will likely find usable arrangements for many scenarios: The key here is to do the opposite of the "my head is a speaker" trick, and do the "my head is the mic" trick: put your head in the potential mic spot, look in the direction it will be facing, and see what is "out there" in that direction. "Hard surfaces" imply brighter, livelier. "Soft" surfaces imply duller, more muted.
If that still doesn't do what you want, then there's another way of doing it: Variable acoustics. Build treatment that can changed on the fly to meet your needs. Surfaces that can be flipped, rotated, slid, opened, closed, or moved in some way, to change the acoustic response of the room. It might be as simple as having a couple of gobos stored outside the room in a closet, that you bring in for tracking or take out for mixing. Or it might be something more sophisticated, built into the room itself, like this:
Variable acoustics devices: adjustable room response at willSo there's a few ideas that you might find helpful, with planning the treatment for your room! The basic advice I can offer is to build at for it's primary purpose: Control Room. Then treat it for the secondary purpose (tracking room) but in such a way that it does not interfere with the primary purpose.
- Stuart -