The more I read, the more I realize that practical experience is the only way to learn about this and the farther I get from starting due to uncertainty.
Getting into the theory a bit also helps!
Not necessarily the math (although that can be very revealing too), but rather basic concepts.
I have started on and am half way done with the cloud because I knew no matter what, that and at least one superchunk would be necessary.
Right! Several superchunks in fact: it's a small room, and as you already noticed, the bass isn't behaving very well. Taming problematic bass needs a lot of treatment. Especially if you plan to use only porous absorption for the bass.
I have done baseline measurements with REW to your specifications but do not want to post the mdat here to reduce confusion because the speakers are at 90 degrees due to my desk needing to be rebuilt to get my video monitors out of the way.
The low end probably won't change a lot from the speaker angles. The mids and highs certainly will, but the low measurements depend mostly on the mix position and the room itself: to a smaller extent on the location of the speaker. What will change most from different speaker positions is the amplitude of the modes and other resonances, but the relationship between frequencies won't be hugely different, and neither will the decay slopes. Those are room-related, mostly.
One other point about your speaker angles: you might find this useful! :
Speaker setup, and the equilateral triangleJoist and deck. And it's "American Affordable" from the early 2000s. In one of the other rooms I can feel the floor move when my 40 pound dog comes in.
Hmmm... not so good. Quick question: do the walls in your room coincide with the walls in the room below? Asked another way: are your walls directly above the walls of the downstairs room? If so, they they might be load-bearing walls, which can help to a certain extent. But your best bet would be to get a structural engineer in there to take a look, and tell you what your loading can be.
For the baffle I was thinking 5/8" particleboard-green glue-3/4" finish plywood.
That would probably work: it's a bit on the light side, but should be OK. Question: You are going to use two mains plus a sub most of the time, correct? In other words, the mains won't be producing the low end, but rather the sub will be handling that?
Is it critical that the soffits go in the corner?
I probably didn't state that too clearly: The speakers will be located in the optimum position for the speakers, and the soffit front baffle will be located around the speakers, as well as possible. That won't be in the corner, but the rest of the soffit structure will be. Even though the speaker-and-baffle won't be covering the corner, there's a lot more inside the soffit that will be! I tend to speak of "the soffit" as being the entire thing: the part that contains the speakers, and the part above and below that, and the part outboard of that, which does go into the room corner, and is what I call the "wing". To my way of thinking, that entire thing is all "The Soffit", since all of the parts are working together to tame the room. Each part doing its own specific thing, of course, but then the combination of all of them doing "The Treatment", as well as holding up the speaker in the right location. The "Soffit" is doing many things at the same time, if it is properly designed.
I know that 5/8"+3/4" will be rigid, but will it be massive enough?
As I mentioned above, its on the low side, but probably in the ball park. However, it's not just the mass by itself: you also need rigidity. In other words, you don't want the baffle flexing and vibrating: it should be immobile across the entire face. Your support system doesn't seem to accomplish that: it only provides support at a couple of spots on the baffle, leaving the rest of it free to "shake, rattle, and roll"...
My idea was to put the speakers on stands behind the soffit. Mains are 55.7lbs and 55.4lbs, and center is 22.4lbs. I have a stock of 1" Sorbothane and a calculator. I figured if the speaker is (actually) decoupled from the stand then it wouldn't matter if the stand was coupled to the floor/soffit?
Here's the reason why I don't do it like that: If you have a speaker sitting on top of a stand, and then you have a fairly hefty voice coil on the woofer whapping around inside the box, thudding back and forth, while the cone is pushing a lot of air around as it moves... well, that can apply more than just a bit of force to the speaker in the front-back direction: it wants to "wobble" And since it is just sitting on a stand, there's nothing to prevent it from doing so! There is nothing to restrain that front-back movement. Which is not a good thing at all, as it messes up the highs as well... think of it this way: if the tweeter is producing frequencies up around the top end, say 17 kHz, then the wavelength is about 20mm (roughly 3/4"). The quarter wave is 5mm. If your woofer is able to move the entire speaker box even slightly, say just 2mm each way back-and-forth (less than 1/8")... well, you can see where this is going! At the furthest point in the "rocking chair" cycle, the tweeter is a quarter wavelength out of phase with where it would be at the other end of the cycle! That's 90°... one hell of a lot, in fact. When you consider that speaker manufacturers knock their heads against walls and spend millions of dollars on research to prevent the cone surfaces from "breaking up" into harmonic resonances of just fractions of a millimeter, it becomes clear that allowing a speaker to rock, wobble, shake, and dance about is a Big Deal. Hence, the need for rigidity in the soffit framing, and the soffit baffle.
Thus, I prefer to mount the speaker with resilient supports on all sides, not just underneath. In fact, very little of the total motion of a speaker is up-and-down! If you rest it in Sorbothane pads, then that's mostly what you are isolating: up-and-down motion... which isn't normally too much of an issue. Most of the motion is front-back, but there can also be side-to-side motion, and certainly vibration. So I prefer to hold the speaker in place in all three dimensions, but resiliently, such that it truly does float.
This is also part of the reason that those silly foam pads for resting speaker on, sold under various brand names, are actually quiet ineffective. Ethan Winer did a series of tests on several of those a few years back, and found that they basically achieve nothing.
I like the base, mid, and top module idea. Can they be frame? Or do they need to be cabinet assemblies?
Probably! But if you use framing, then it would have to be floor-to-ceiling... sort of the size of a double bed frame...
Also, when you say wings are you speaking of bits beyond what I was calling the "extended baffle" in the drawings? I was thinking that I would need to use the area to the sides of my position for absorption, or... does the soffit deal with that in another manner.
The basic function of a soffit is to remove the speaker from the room which eliminates or greatly reduces many of the artifacts associated with having a speaker inside the room. Edge diffraction, front wall SBIR, power imbalance, etc. They are gone, because they can only happen when a speaker does NOT have an infinite baffle. Of course, in a realistically sized room, you cannot actually have a true infinite baffle, since it would have to extend several full wavelengths in all directions, and he wavelength for 20 Hz is nearly 57 feet.... In all real-world studios, the actual baffle size is somewhat less than "infinite"! And that's fine, because there are some "tricks" that can be used to make it "seem" bigger than it really is, as far as he sound waves are concerned. But even a simple baffle without any "trick" will still reduce the effects of those nasty things.
What I call the "wing" is one of those tricks: the "wing" is the part that extends from the outer edge of the soffit baffle per sé, out to the side wall. The angle is different from that of the actual baffle. In addition to helping create the RFZ condition, it also makes the baffle "appear" wider, for low frequency waves.
Now, with a true 5.1 room, wings need very, very careful design, because they are also located exactly where the rear surrounds will produce high-level specular reflections back to the mix position! So 5.1 rooms and soffits are different from pure 2.0 soffits and room treatment.
(The guy who designed my studio had no absorption in front of about 3 feet behind my mix position. It was all very rigid. It worked well. But some people mentioned it was an outdated design.)
That's classic "LEDE" design. "Live End - Dead End". That's a concept that died 20 years ago! Nobody in their right mind builds pure LEDE rooms these days. Yes, they do work, but they are fatiguing. It's not natural to your ears or brain, and those have to work extra hard to make sense of nonsense. So at the end of the day, you end up feeling exhausted, without really knowing why. More modern design concepts, such as RFZ, CID, NER, etc. are mostly extensions of the LEDE concept, that keep the same basic goals in place, but achieve it in different ways that are NOT fatiguing, like LEDE is. The people who told you it was outdated are absolute correct!
Depending on how well I'm interpreting REW the modal region is surprisingly even in frequency response with the only worrying dip at 2-1-1. However, sustain is off the charts in the first two octaves and bass response to the ear is anemic. It is not tracking the signal in any useful manner.
Yup! Typical bass problems for small rooms that are untreated (or poorly treated), and not laid out optimally.
There's likely a LOT more in the REW data that you maybe haven't see yet. Post the MDAT, and I'll take a quick look when I have a chance.
Trying to interpret the ETC with string has lead me to believe that the first BIG reflection is coming off the front wall.
That's unusual! I'd bet that your first big reflections are coming from the side walls, and floor, and perhaps the ceiling. What you might be seeing, is SBIR. That's not really a "reflection" as such, but rather a phase cancellation of a reflection. And it will always be very low down on the spectrum: it is governed by one thing alone: distance between the speaker face, and the front wall. I'm not sure if you have seen the "walking mic" test instructions? If not, try that process, and you'll easily identify SBIR... as well as several other issues.
* Design soffit and place speakers. Baseline room.
Actually, it would be better to do that the other way around! First test the room extensively with REW, then based on that figure out the best locations for the speakers and mix position. Then design the soffit accordingly. A comprehensive set of REW data should lead you to good locations for your ears and speakers. Then everything else falls into place around that.
* Design soffit and place speakers. Baseline room.
* Build corners, cloud, and desk. Measure.
* Build soffit. Measure.
* At this point I'm really getting lost, but I had intended to use the side walls (wings?) to absorb early reflections at ear level and introduce early reflections at floor level -built deep enough for more bass trapping with the bottoms sealed in attempt to use slat spacing to do some additive narrower modal absorption. Measure.
* Continue to build floor to ceiling traps all the way around. Install slats on lower sides. Measure.
* Try to figure out how to align decay times and introduce liveliness that I suspect will get lost with so much bass trapping. Measure.
* Repeat.
It sounds like you are attempting to combine several design concepts at once! I would suggest just choosing one, and designing the room from that basis. It is possible to "mix and match", yes, but I find it easier to just set an acosutic goal, then follow a concept that will achieve it. Personally, I feel that the RFZ concept makes the most sense all around, and I use that as the basis for most of the rooms I design... with some of my own modifications!
But others prefer different design concepts. As long as you stay consistent to the overall approach of the design concept you choose, then you should be good results.
In fact, all of the best design concepts have the same goals in mind: pretty much as defined in ITU BS-1116-3 and EBU Tech.3276. Meet either of those, and your room will be fantastic. That's not easy to do, but getting close to those specs will still get you a good room.
And the real truth of the matter is, I learn much better in practice. Once I have experience the more sense the reference material makes. Plus, my math skills are nil.
You don't need a lot of math, actually. Some, yes, but nothing too complex. Just basic high-school stuff. What I find to be more important that the math, is to understand the concept that the math explains. Simple example: W=c/f. Wavelength is speed of sound over frequency. Math makes that sound complex, but understanding it makes it simple: sound waves move at a constant speed through air, sound waves consist of "cycles" of high and low pressure, so it is logical that there must be a certain distance between one wave "cycle" and the next wave "cycle" that comes right behind the first one. The distance between those two "cycles" is the "length" of the wave, and it makes sense that you can figure that our by seeing how fast the wave goes, and measuring how many cycles it has in each second. Thus: wavelength is the speed of sound divided by the frequency. So, if you know that the wave is traveling at 1100 feet each second, and you get ten waves arriving every second, then the distance between them must be 1100 / 10 = 110 feet. It's a lot easier to understand the equation, when you have a mental picture of what is going on!
I find acoustics fascinating and beautiful but it's not my first concern here.
Hmmm... It should be! Not in the sense that you need to understand the equations for triple-leaf isolation walls, but in the sense that the very reason why you even have a studio, is because you want to listen to clean, clear, precise sound: and achieving that, is called "acoustics"!
If I had ample funds you'd be on your way to my new property at your next calendar opening.
Well, I've been to Las Vegas many times (I used to attend the famous NAB trade show every year), and I sure wouldn't mind going back again! But actually there's no need. In fact, I very seldom go to the locations of studios that I design: with modern technology, it is entirely possible to do the entire analysis, design, tuning and tweaking remotely. The Internet makes that possible, along with tools like REW and SketchUp, as well as Skype, Zoom... and the plain old telephone! That makes things MUCH cheaper for clients: paying for a studio designer to hop on a plane and do a site visit is a huge expense... and unnecessary! (Except maybe in unusual cases). It's much less expensive to just pay for the actual consulting service, or specific design. I do like to travel, as much as anyone, but it isn't justifiable for the vast majority of my clients to pay for my time and expenses to do that. I try to keep costs down for my clients, since money doesn't grow on trees!
Ooh, another thing I overlooked concentrating on the wrong aspect. I have a huge dip at what seems to be caused by 2-1-1 centered at what seems to be 0-0-2. So I was trying to get the absorption down below 140. That gave me two air gaps, one in the trap and one between it and the ceiling. Am I correct in thinking that the hardback and slant will redirect residual energy to the rear of the room? Do I want it less absorbent?
The hard-back accomplishes a couple of things at once: yes, it does reflect some energy at some frequencies towards the rear of the room, where it should be somewhat absorbed and somewhat diffused before arriving back at your ears after the ITDG, but that is frequency dependent, speaker dependent.. and angle dependent! You need to get the tilt angle correct to ensure that you really are getting a good RFZ around the mix position, in the vertical plane. The other thing that the hard-back can help with, is some modal issues: if it is large enough, and suitably located, it can have an effect on "smearing" the modes a little: basically, lowering and broadening the Q. It can do other things to, when used creatively...
My desk is unruly and I don't know that lowering it will be easy,
Careful with big chunky desks that sit up high! They have a profound (and detrimental) effect on room acoustics! A bad choice in desks can really undo a lot of the hard work you put into the rest of the room. The best concept for a desk is low profile, "open" construction, and no large, flat surfaces. Especially vertical ones. Angles are good, holes are good, and keep it all down low: no shelves or gear sticking up. Like this:
The Soundman M1 studio deskThanks again for your attention to the subject and contribution to the world. Sound is too cool to not enjoy at it's best.
Very true! Getting your acoustics under control, approaching BS-1116-3 specs, will certainly accomplish that!
- Stuart -
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I will have fun looking these over. The sub is not haphazardly placed but I won't say it can't be better.The attached mdat is in your format. No extra measurements.