I can't use the wall with the window to build a soffit there, because there's a heater underneath the window. If I close up all of that, I no longer have heating in the room
Then don't close it up!
Make a soffit that leaves the heater free. Or just don't use that heater, and set up a different heater elsewhere in the room...
I've been playing with REW Room Simulator,
It's a useful tool, but all it tells you is the predicted frequency response based on modal response. That's not the entire picture of the room response! Not by any means. Very far from it.
I've noticed that when I turn everything 90 degrees counte clockwise (the long wall without the door becomes the fromt wall), the entire predicted spectrum becomes smoother, and the massive dip at 80 - 100Hz shifts up to just above 100Hz,
... and you also move your head much closer to the rear wall, where you will be getting major reflections inside the Haas time, and thus messing with your psycho-acoustic perception of the sound... Early reflections from the back wall are a big "no-no" in studio design! You want your head as far as possible from the rear wall, in order to meet (or at least approach) the "20-20" criteria (hence my screen name: it has nothing to do with the year 2020...
). the "20-20" criteria says that you must avoid all reflections within the first 20ms of the direct sound, and even then they must be 20 dB down form the direct sound. This is a basic criteria for successful control room design. And you cannot achieve that with the rear wall just a short distance behind your head! Your room is only 3 m wide, and your head is about two thirds of that distance.... so your head is just 1 m from the rear wall. That's barely 6 ms for the reflections from the rear wall. With the lengthwise orientation, your room is 4.6m long and your head is about one third of that distance, so it's about 3 from the rear wall. That's about 19.6 ms for the reflection from the rear wall.... Very close to where it needs to be.
So what's the problem? Well, if your ears and brain hear the direct sound, and also a reflection of the direct sound both arriving within 20 ms of each other, then your brain is unable to figure out that it is actually two separate sounds. They have to further apart than 20 ms to do that. Over 30 ms is better, but 20 is decent. So, since your ears and brain don't realize that you are hearing a reflection, instead they assume that the combination of the two is just one single sound. And since that "combination" is very different from each of the individual sounds, your brain decides that it actually came from a different direction, and that the frequency curve was different from what it really was...
This is all about the field of psycho-acoustics: how your brain
perceives the sound, rather than what a mic would measure. Mics and ears are very different: they do not work the same. Since you have a pair of ears, and since each ear picks up a slightly different version of any sound (because they are spaced apart, and have your head in between), your brain uses the subtle timing differences and level differences and phase differences, to figure which direction the sound came from. All those little curly folds and wrinkles of your ears are actually a key part to this, since they provide additional timing, phase and level differences that your amazing ears can use to figure things out. In fact, those folds and wrinkles create specific interference patterns inside your ear canal, which your ear then recognizes as indicating where the sound came from. The problem is, that when you get a sound plus its reflection in less that 20 ms, and less the 20 dB difference, the effect is exactly the same as what the wrinkles and folds would cause from just the direct sound! That totally confuses your poor old ears, and messes with your brain: there are now two sets of interference patterns in your ear canal: one from the "wrinkles and folds", and the other from the reflected sound that arrive in less than 20 ms. So your brain does what it normally does with all such interference patterns: it interprets that as meaning the sound came from ANOTHER direction, different from the one it really came from! As you can imagine this is not a good things for a control room... The room is lying to your brain, messing with it's ability to correctly decide where the sound came from (panning), and what the frequencies were (eq)....
So, do avoid a room layout where you get reflections within 20ms....
So this looks like a good compromise. I know: Stuart is allergic to compromise (and rightfully so!).
Actually, studio design is all about compromises! That's what I do, all day every day when designing studios: play off one aspect against another, compromising some things in order to improve others... The trick is to continue juggling all those compromises, until each one is at it's lowest level, and the studio is optimized...
However, this room was not purpose designed to be a mix studio.
To be very honest, very few of the studios I design are purpose-designed! More often than not, I just get a pre-existing room with fixed dimensions, shape, doors, windows, etc. Then I have to fiddle with all those compromises, to make it work.
a soffit seems like too big and too expensice an endeavour for me at this time. There's so much work and materials involved, it's going to be out of my budget and outside of my skill set.
Can you use a hammer? Can you use a saw? Then you have the skill set. Can you buy 2x4 framing at your local hardware store? Can you buy sheets of MDF, and nails, and insulation? They there's no problems with materials either!
When I follow the proposed plan and the results are good, I will save up money and try the soffit route, after all.
Which implies that you will then have to trash most of the treatment that you had built up to that point, because it won't be applicable any more... The treatment is different for a room with soffits, as compared to a room without soffits. Very different. If you want to build soffits later, that basically means you will need to re-do most of the room...
But at this time I have no idea what I'm doing when "designing" one.
The basic concept is simple: A big plank of wood with a hole in it to poke the speaker through, and a frame to support it. That's all it is, basically.
I want to try what happens when I turn everything 90 degrees counter clockwise.
Try it by all means! And post the REW data, so we can show you just how bad it is...
Then you can turn it back again...
Can somebody tell me what exactly the purpose is of a cloud in a small room?
A properly designed cloud accomplishes many things: One is modal smearing, second is RFZ, third is ceiling treatment, forth is eliminating the ceiling bounce, fifth is overall room decay response, sixth is that it looks cool, ...etc.
The way I see it, in my room the mode between floor and ceiling lies at 71Hz, which is outside the range of resistance based absorption.
Ummmm... Your FIRST axial room mode in the vertical direction is at 71.8 Hz, yes, but the SECOND vertical axial mode is at 143.5 Hz, and the THIRD vertical axial is at 215.3. But you also have tangentials involving the ceiling at 80.8, 92.1, 103.4, 118.4, 132.7, 136, 141..... And you have obliques at 99.4, 118.4, 141.0..... All of those are treatable with 15cm of suitable porous insulation, with the possible exception of the first two (71.8, and 80.8 ) All the others are with the range. But that doesn't matter, since the lowest frequencies will also be hit by the back of the cloud, or by the membrane effect, or by the air gap above the cloud, or by other design features that can be built into a cloud.
Here's an example from a room that was recently completed by one of my clients. Here's the waterfall plot before the cloud went in:
FCR-REW-WF-10-500--before-cloud.png
And then again AFTER the cloud was in place:
FCR-REW-WF-10-500--after-cloud-first-test.png
I think you can see the massive difference, even down at 70 Hz, which you are worried about..
Here's the spectrograms from the same tests. Before:
FCR-REW-SP-10-500--before-cloud.png
And AFTER:
FCR-REW-SP-10-500--after-cloud-first-test.png
Once again, you can see the massive difference, even in the 70 Hz region.
And what causes the dip at around 80Hz - 100Hz in both scenario's?
Probably floor bounce. I'm not sure if the algorithm in Room Sim takes that into account, but that's typical of all small rooms. There's always a dip somewhere in that region, which is set by the distance between the mix position and the speakers.
Simulated, the dip becomes significantly less deep, when I move closer to the front wall
Yup. Because it will move to higher frequency as you get closer to the speaker (shorter path), and thus is partly compensated by modal issues in the same region.
In the Short Throw scenario the irregularity around 110Hz is about as good as it can get in this simulated, untreated room...
so what?
I would certainly not base my room layout and design on a very basic simulation of frequency response, and worse still, without any treatment in the room!
Here's what it looks like with minimal typical treatment:
Sound-Guy--room-sim-with-treatment.jpg
Quite a difference!
Besides, you are only looking at frequency response, which isn't even the most important aspect of a room's acoustics! You should be looking at the time-domain response. That's what really matters. You should never base major layout or treatment decisions on frequency response alone. Without the context of time-domain response and phase response, the frequency response graph is not much use... especially when it is merely a simulation... You would also want to know about reflections, diffusion, the ITDG, the shape of the impulse response, and many other things. FR is just one small aspect of overall acoustic response: don't focus on that too much: it really isn't that important, until you get to the final stage of tuning.
Things to ponder....
Or calculate...
- Stuart -
I'm still learning about acoustics. It seems the more I learn, the more I know I don't know. When is one "ready" to start, or at least develop a good plan? With every step I take, it seems there are more things to concider, so I need to rework the plan. Still motivated, but I'm starting to get impatient. I want to get started. But only if the plan is good.