It is concrete underneath. I think the walls are built on the floor, so that might be problematic to removing the floor, but ill have a look.
If it is concrete under there, then it's a no brainer!
I can't tell you what to do, of course, but I can tell you what I would do if that were my room: If I had a room with a low ceiling and a "floated" floor that isn't floated at all, and instead is basically a drum and a panel trap at the same time, I would not hesitate. You'd find me down on my knees with a sawzall and a hammer, ripping that sucker out, with a huge grin on my face!
Assuming it is up on 2x4's, and there's an couple of layers of OSB, ply, or some such, plus the rubber pucks, you will gain something like 15cm of head room, and you will eliminate the drum head and the panel trap, all in one go! What's not to like about that?
Your room height goes from 216 cm to 231 cm in one huge jump, adding 10% to your room volume: It is now 22 m3, instead of 20 m3. Your Schroeder frequency dives from 170 to 155, your Bonello plot is a bit smoother... Lots of good things happening.
Incidentally, I bought a shed load (60msq!) of hardwood (teak?) parquet floor tiles today that we intend to use in the control room. Would this change the matter with regard to keeping the floor as is?
It would not change much. You'll still have a "floated" floor that doesn't float (which makes it worse than a non-floated floor), and you still have a resonant cavity inside that floor, and it is still a drum head. And that flooring would look really cool, laid directly on the concrete slab. It would be a great acoustic surface, as well...
I think the walls are built on the floor,
... and the floor is resting on rubber pucks????
Not only is not floating, but that's also likely not legal. How did that even pass inspection?
But it's not such a big deal as it might seem: It is possible to pull out the floor re-do the bottom part of the wall correctly, so it rests on the slab. You'll need the help of a structural engineer, probably, but its not as hard as it sounds to support each wall with bracing / jacks / whatever while you pull out the bits of incorrect floor from under it, and add the missing parts to the bottom of the wall. It might sound scary, but it is feasible.
The "north" wall in the new room image, i.e. behind the mixing desk, will have the slats
The wall at the top of the page? Where your speakers will be? That's the front wall of the room. It's never a good idea to put tuned devices on the front wall, as they can change the frequency response and phase response of the sound reaching your ears. In any event, that wall will need 10cm of OC-703 directly between the speakers and the hard, solid, rigid actual wall surface, to deal with the SBIR and edge diffraction artifacts coming back at you after bouncing off the actual wall. Those are very low frequency things, and they won't "see" your slats at all: they will behave as though your slats were not even there.
I would suggest not trying to tune the front wall. There won't be any treatable mid-range issues on the front wall in any case, so it would not be very effective. Leave that wall either solid, or make it fully absorbent, depending on which room design concept you are going to follow. I have only ever done slats on the front wall in one control room, and that was for some rather unusual and very specific reasons. Even then, it was not the center section of the front wall, but rather way out, beyond the speakers, and in a much, much bigger room than yours. Here's a link:
http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20471
For your room, personally I would leave it as hard, solid, and massive as I possibly could. I would out superchunks in both front corners, panels of 703 between the speakers and the wall, then leave the small section in the middle bare.
and hope the REW test will give us an indication of what to target.
REW will show you the major issues, yes, and after you fix those, then it will show you the less major issues that were hidden and masked by the major ones. And after you fix
those, it will show you yet smaller issues... and after you fix those... etc. Ad infinitum. I would not expect that REW will reveal much that can be fixed by slot walls on the front of the room. I would expect REW to show you that you have SBIR issues with the rear wall, and perhaps with the front wall too, but you can't fix SBIR with slot walls. REW will show you some modal issues too, very probably, but you can't fix those with slot walls either. REW will doubtless also highlight reflections that are arriving at the mix position way too early, or way to powerfully, and slot walls can't fix those. It will also show you some frequency response issues that MIGHT be fixable with slot walls, but I don't think you'll have enough volume inside your slot walls to make a huge difference.
Helmholtz resonators need to encompass a fairly large percentage of the entire room volume in order to be effective, and they have to be deep enough that they actually can be resonant at the frequencies that need treating, and also not so deep that the wavelength is shorter than the cavity depth and the slat width. And the device needs to be located at a point in the room where there is a pressure mode of the frequency that needs to be treated. For example, if you are wanting to treat an issue that is related to the ceiling/floor axis, then putting your devices on the side walls would do nothing, since it would never "see" that particular problem.
Also, Helmholtz resonators are notoriously difficult to tune: Text book equations are one thing (and many of those equations are wrong anyway, perpetuating the same old misprinted "+" sign instead of "x" sign, from decades ago!), but the real world is another thing. Materials are not perfect, workmanship is not perfect, the actual air temperature might be different from what you used in your prediction equation, there might be measurement in inaccuracies... trying to hit a specific frequency is nowhere near as easy as it sounds from reading a text book. If you do use slot walls, then tune them broad-band, low Q, across the entire mid-range, and be content with whatever small effect they give you. It really isn't worth the effort of trying to tune them perfectly to hit exact frequencies.
Considering all of the above, I would suggest not bothering with them at all. The room is tiny, there's not enough available surface areas (maybe 25%) where you could put them, and I don't see them being very useful. Stick with absorption. That's abotu all you can do in a small room.
Perhaps the outer thirds, leaving the middle third for a large screen to be mounted? (we intend to mount a large screen there).
You can, indeed, hang a large screen in the middle of the front wall, between the speakers. As long as it is not larger than the distance between the speakers (that will be determined when you do the calculations for the correct room geometry), then that's fine. Hanging a screen would effect the slot wall behind it for some frequencies, but not for others....
Re: acoustic foam, we have Auralex pads
That's fine. At least you have proper foam, from a reputable manufacturer.
or are too ripped for use (they were all up when we took over the place and had to take them down).
Don't throw away those damaged scraps! You can still use them. Keep all the bits and pieces of your left-over foam and insulation, and dump them inside your superchunks. They will work quite well in there.
The cloud is 1500x1500x170.
That's rather small.
It has 100mm rockwool, with the remaining depth between that and the ceiling.
No hard back?
You would get a better effect by making it thinner (120mm, for example, instead of 170), then putting a thick, rigid, massive, heavy hard back on top of it (eg. 19mm MDF), and angling it slightly (lower over the speakers, higher over the desk), then stuffing some more of your foam craps on top. That would be hard to do with a low ceiling, but much easier to do once you gain back the lost height that the "floated" floor is robbing you of....
The surface is covered with carpet and has some auralex pads stuck on too.
The carpet isn't doing much, except making the room sound dull: Ditch that, and just cover the cloud with thin plastic (such as painter's drop cloth) to keep the mineral wool fibers from filtering down all over you and your gear, as time passes, then cover that with nice looking fabric of your choice. Take a look at the clouds in the link I gave you above.
The desk in the image is kind of indicative of what we have! We have a Soundtracs Megas 40ch, 12 buss desk. Approx. 1m deep, 1.8m long!
You are not going to like what I am about to say, and even though that's a great console, it is just way too big for that room. Putting a large consoles in a small room is just begging for problems. I can start listing some of them, if you want . . .
1) Mid-range mud. The console surface will be very close to both your speakers and your ears. That's a sure-fire, guaranteed recipe for major reflections, comb-filtering, and phasing artifacts. The sound coming from the speakers will be greatly affected by the surface itself (lows and mid-lows) as well as by the control knobs and buttons (high-mids). The mid-range frequency response curve will resemble the mountains of some distant alien planet, and there is absolutely nothing you can do about that: no treatment is possible, because the issue is not related to the room at all. The mangled sound will reach your ears long before it reaches the room walls, where it could be treated, but that would be far too late....
2) Low-end "flummph". That's a very technical term that I just invented to describe the way the low end falls apart when there are large objects destroying these nice long waves that would otherwise have got through cleanly. In other words, your low end will not be tight. It will be muffled, unclear, but also over-represented. Your kick and toms will sound like wet cardboard boxes: No clean, hard "thump!" Just a waffly baggy "flumph".
3) Phase cancellation. You will get multiple reflected versions of the same sound hitting your ears with slightly different timing, and therefor slight delays. Those will create phase cancellations for some frequencies, but not for others, but that will change as you move your head to different positions relative to the console....
4) Early reflections: A cardinal rule fo control room design is that no reflections should reach the engineer's ears until at least 20ms after the direct sound has arrived, and even then should be 20 dB lower in intensity. With a massive hard flat surface just a few inches from the speakers, and a few inches form the engineer's ears, that is impossible. Those reflections will be arriving with just a couple of ms, or less, and will be practically the same intensity, maybe a dB or two lower, if that. The result is a psycho-acoustic mess! That destroys all of the clues that the highly precise design of your ears and your brain use to determine frequency response and directionality. Your brain will interpret the resulting grunge as being a different tone that came from a different direction. In other words, you lose your sense of directionality and of tonality. In simple terms, blurred sound-stage, unclear stereo image, messed up sense of musical notes.
Want me to go on?
I would seriously consider getting rid of that monster, even though it is a great console, and replacing it with a DAW, or a minimalist console, and a minimalist desk. That room is just too small to be able to successfully fit such a big console in. Either get a much bigger room, or get a much smaller console.
The room will be used as both for production and mixing, hence the keyboard and rack images.
Ummmm. Nope! Just nope. It's a tiny room! You cannot have big things in it! Each of those will take up a large percentage of the entire room volume, messing up a large section of the room response. You MIGHT be able to fit a small keyboard on a slide-out tray under the desk, but that's about it.
We will need two seats in there too,
Nope. Not in that room. If you do, nobody will be in the sweet spot. It is a tiny room, the sweet spot will bin minuscule, and there is no way in hell that two heads could be in it. It's going to be tight to even get ONE head in it! You will most certainly hear large changes in frequency response as you move your head around, even like it is, even if you set it all up and treat it perfectly. For critical listening, the engineer will need to keep his head fairly still, since moving it will give him a different "image". Yet another reason for not having a console where the engineer needs to move side to side to reach distant faders.....
and were also going to make a small "pew" on the back wall for guests.
The back wall will have about 15 to 20cm of absorption on it, to deal with the bass issues, modal problems, and help some with SBIR. You can put a "pew" in front of that if you want, but nobody on that pew will be able to do any critical listening. They will be right at the point where all the modal issues and SBIR issues are at their peak.
and puts the listening spot close to the centre of the room,
That's the worst possible location in the room. All the first-order modal peaks and second-order modal nulls are at their maximum intensities there, in all three axes...
we have to make the best of it for now.
Unfortunately, from what you describe, that "best of it" is actually somewhere between "worst possible" and #even worse than that"!
From what i can tell, there seems to be a problem around the 79-80hz area, and 100hz. This seems to be corroborated by the Amroc calcs too. This suggests we will have to take direct action on these in particular. Hopefully the REW tests will shed some light on the rest.
Here's what your low-end response will look like, at the mix position in the center of the room, assuming optimal geometry, basic treatment, no console, and no racks:
silentCoup-FR-sim.jpg
Not a pretty picture! I would not like to try mixing in that room.... That grapsh is showing only the predicted frequency response from the modal issues. It does not show rear-wall SBIR issues. There will be an SBIR dip at around 100 Hz, which is a real fun situation since it is combined with both an axial mode and also a tangential mode that are already reinforcing each other! Which of course implies that there will also be a corresponding 6 dB peak at around 200 Hz, then a dip at 300 Hz, peak at 400, dip at 500... all the way up the scale... Can you say "major comb filter"?
Once again, I can't tell you what to do, but know what I know about acoustics, if that were my room I would absolutely not put any furniture in it, except for a very small desk with my DAW keyboard, mouse and monitor on it, perhaps with very small, low.profile "wings" to either side with my key pre-amps, interface, and a couple of other critical rack-able items in them (Sterling desk style...), and maybe a very small single-seat sofa towards the rear, as far away from the wall as I can get it while still leaving space for my own chair. And that's it! Nothing more. I would have massive bass trapping across the entire rear wall, with a couple of very broad slats across it at strategic locations, large superchunks in each vertical corner and the wall/ceiling corner, superchunks in both front vertical corners and both front horizontal corners, thick absorption in the first reflection points on the side walls, 10cm OC-703 panels between the speakers and the front wall, a large, hard-backed, angled cloud with extra insulation on top, and another panel of 703 on the rest of the ceiling, behind the cloud. I might add a couple of other items, if REW showed me something really bad, but not much more than that. That would give me border-line usable acoustics, but if I tried to put anything more in the room, that would make things worse, so it would just be me and my DAW, and acceptable acoustics.
Hold tight for the REW report!
Looking forward to it! Let's see how closely reality matches prediction! I'm assuming that you already have your speakers set up correctly, with the optimal geometry for that room?
Please also post a couple of pictures of how the room looks at the time you do the REW tests.
- Stuart -
The desk in the image is kind of indicative of what we have! We have a Soundtracs Megas 40ch, 12 buss desk. Approx. 1m deep, 1.8m long! The room will be used as both for production and mixing, hence the keyboard and rack images. We will need two seats in there too, and were also going to make a small "pew" on the back wall for guests.
That's weird! So if your system only works one channel at a time, then how on earth are you going to make music in there???? You better get that fixed, fast. Without seeing how both speakers together interact with the room, it will be pretty hard to plan the treatment, and then figure out if the treatment is working or not...
Smart move! And I'll bet it didn't take more than a few hours... 
