Control Room Design Phase

Have a great opportunity to grab a room to build a dedicated mixing control room. In the design phase. I have dipped into this forum for years but not posted much. The room is in an industrial building that has been partitioned. Must have been some kind of store room. Brick all around. Kitchen and bathroom to one side separated from main room by brick wall. It is a perfect room to isolate. My main objective is to design a mix room that I can rely on to be of a very high standard acoustically. I have had a few studios over the years - my control rooms have mainly followed the LEDE style. But this time I wanted to try something closer to the RFZ style, controlling reflections and using diffusion on the back wall to create a more lively sound. I have always found LEDE rooms (some better than others) to be a bit tiring to work in. More often too dead. I would like to use less absorption than in the past but would like to hear what people recommend. I found that my dimensions can be catered to Loudens ratio A 1:1.4:1.9 The average wall dimensions I am working towards are 3.125m: 4.375m: 5.9375m. Which is quite exciting to say the least. So here is where I am up to so far. Would appreciate any ideas on how to make it better. Comments about the angles much appreciated.. I must confess that I cannot use Sketchup and I prefer to draw out plans on grid paper. I hope its not too offensive. Would love some feedback on the angles of the walls and ceiling. Am I on the right track? 1 square = 125mm I have a big old analogue desk - the meter bridge is 1.10m high. Added to that I would like to add a pair of nearfields and auratones on the meter bridge. So consequently I have decided to angle the soffit wall as shown in the sketch. Love to have big monitors when tracking bands but really I mix on nearfields. I am a little bit confused about using nearfields. Surely you cant design a room for both types of monitors. What can be done to maximise the performance of near fields as well as soffit mount mains? I assume it would be a good idea to put broadband absorbers between the soffit mount speakers on the front wall? Any other solutions staring me straight in the face? Another query. I will not have enough room to put a decent size ventilation silencer between my inside leaf and the outside leaf brickwork. Is there any reason why a silencer cannot be placed on the inside of the studio? Obviously I would have to disguise or build as aesthetically pleasing as possible. Possible other option is to put silencer on the other side of the brick wall outer leaf. Although I have seen many references to silencers on the forum I am struggling to find any info on exact placement. Is there a cross sectional diagram of silencer mounting out there. Even in Rod Gervais books there is a pic of one but no info on where to put it. Or does it not really matter - so long as there is no rigid coupling between leaves (using flexiduct I presume would be ok) the silencer would attenuate any sound which escaped through the duct?? Help Ah and budget about £15K. I have gear.

Speaker soffit wall and back wall corners are with bass hangers

Hi again, "mago". Welcome back! :)

The room is in an industrial building that has been partitioned. Must have been some kind of store room. Brick all around.

Sounds hopeful! What about the floor and ceiling?

I have always found LEDE rooms (some better than others) to be a bit tiring to work in. More often too dead.

Personally, I think that's the main reason for the concept to have lost favor. Very few rooms built these days are pure LEDE, in the original concept. RFZ is an extension of LEDE, but turned around and better balanced. And much more logical, too.

I would like to use less absorption than in the past but would like to hear what people recommend.

Absolutely. But perhaps the issue with LEDE was that all of the absorption was in one place, up front. If the same amount of absorption is spread around the room more evenly, it sounds much better. There's an optimal amount of absorption that a room needs, based on its volume and surfaces, and specified by organizations such as ITU, EBU, AES, and others. They all agree that the basic concept is to give the room a neutral sound, not too live and not too dead, with carefully defined decay times for different frequency regions. Follow those guidelines, and the room should work out well, be accurate, and your mixes should translate cleanly.

The average wall dimensions I am working towards are 3.125m: 4.375m: 5.9375m. Which is quite exciting to say the least.

And maybe a little too accurate! :shock: :!: It would be pretty hard to build a room accurate to tenths of a millimeter!! :) Jokes aside, I'm assuming that 3.12 is the height? NICE! Lucky you. So your floor area is roughly 25m2, and room volume is aprox. 80 m3. Very nice. That meets the ITU/EBU specs of minimum size for a critical listening room.

I must confess that I cannot use Sketchup

There are some pretty good tutorials that will get you started. It's a very powerful, very useful tool, once you get over the initial learning curve. Some of the concepts are a little strange, but once you figure them out you'll find it really useful.

I prefer to draw out plans on grid paper.

The problem with sketching on paper is that it is only 2D. Sound is 3D. Everything about your room has to be worked in 3D, especially if you are splaying walls, angling the front of your ceiling, and also tilting your soffits: all of that is a great idea, acoustically, but it does produce compound angles that are hard to visualize on 2D paper. And when it comes time to ray-trace your speaker sound fields, well, I can't even imagine the complicated math you'd need to use to do that in 3D on 2D paper! :shock: In SketchUp it is simple, and visual. So I'd suggest that you have another go with SketchUp. Try working through a couple of the basic tutorial videos, to get the hang of the basics, and I'm betting you'll get it.

Would love some feedback on the angles of the walls and ceiling. Am I on the right track?

Hard to say! :) That's 2D paper, and sound works in 3D, so it's difficult to figure out if your angles are good or not. Did you ray-trace? To me it seems like you still have a lot of reflections coming off your side walls. The walls are not angled enough to create a true RFZ. You seem to have them angled at about 6°, but that won't be enough. To avoid wasting space, you can just angle the front part of the side walls, then leave the rear part parallel. If you angle the entire wall enough to create a good RFZ, you'll end up with a very narrow front and a very wide back. Also, what is the angle of your speaker soffits? They seem to be tilted a bit too steeply. The largest tilt angle you want normally is about 7°, and the absolute limit is 10°. Beyond that, you start getting strange psycho-acoustic effects going on, due the sound coming at your ears from up-above, instead of straight ahead. It also looks like you will have reflections off the console surface, with the speakers up that high. To me, it also looks like you are sitting too far forward in the room, too close to the main speakers and front wall.

Added to that I would like to add a pair of nearfields and auratones on the meter bridge.

Despite what you see in so many "pro" studios, putting speakers on the meter bridge is about the worst possible place for them. You'd think that the pros who work in those studios would realize, but it's probably a case of "Everyone does it like that, so it must be right!". Wrong. With speakers on the meter bridge, you WILL get first reflections off the console surface. Guaranteed. You might also get earl-early sound, as well vibrations and transmission through the meter bridge itself. If there's one really bad spot to put speakers from the acoustic point of view, the meter bridge is it! Instead, put them on stands just behind the meter bridge. That pretty much solves the problem! Obvious and logical, but so few places do that... I guess there's an awful lot of places that just don't understand the terrible acoustic consequences of "speakers on bridges", so they do it anyway... Oh well... maybe they'll figure it out one day.

So consequently I have decided to angle the soffit wall as shown in the sketch.

That's fine, and you can tilt your soffits if you need to, but as I mentioned above, there are limits to how far you can go with that until you start running into issues of clarity, accuracy, sweet spot depth, and things like that, as well as the ability of the ears and brain to process the sound properly and produce an accurate depiction of what the speakers are actually emitting. The higher you place your speakers, the more reflections you get from your console / desk / bridge. Simple geometry. And the more reflections you get in your face, the more comb filtering is happening, as well as phasing, cancellations, etc. As long as you ray-trace carefully and move things around until you actually do have a clear RFZ around your head, then you can do that, but higher speakers and larger tilt angles make it much harder. I try to avoid tilting speakers more than 5°, if I can help it. There also seems to be a problem with the acoustic axes you are drawing from your speakers: You seem to be showing that the axis is in the geometric center of the speaker (middle of the front face), but that is very unlikely, unless you have some unusual speakers. The acoustic axis is normally much closer to the tweeter than the woofer, and may even be offset to one side, if the tweeter is not centered. Every speaker is different, so it would help to know what speakers you have (make and model).

am a little bit confused about using nearfields. Surely you cant design a room for both types of monitors.

Actually, you CAN design a room like that, if you get the positions and angles correct. Of course, the nearfields can never be accurate or clean like the mains can, simply because they are not mounted in soffits, and therefor suffer from all the same illnesses as any other speaker that is not soffit mounted. Also, for the same reason, the nearfields cannot produce a reflection free zone. Only the mains can do that. Actually, there is one way to have both nearfields and mains work optimally, without artifacts: mount them BOTH in the soffit...

I assume it would be a good idea to put broadband absorbers between the soffit mount speakers on the front wall?

You can't really do much of that, since that would mess up the carefully shaped RFZ for the mains. It might be possible to put some absorption on the front face of the soffits and the front wall, but that would have to be part of the overall room design.

Is there any reason why a silencer cannot be placed on the inside of the studio?

No reason at all! Silencers do not have to go in between the leaves: they can be outside the room, or inside the room, or better still: both. As long as you decouple the duct in the middle, between the two leaves, and build the silencer solidly, and design it for this situation, then there's no problem.

Obviously I would have to disguise or build as aesthetically pleasing as possible.

You could easily disguise at as part of the acoustic treatment of the room. But actually you DO have space for putting in between the leaves... Above the angled front ceiling, you have lots of space for your silencer. :)

Although I have seen many references to silencers on the forum I am struggling to find any info on exact placement. Is there a cross sectional diagram of silencer mounting out there. Even in Rod Gervais books there is a pic of one but no info on where to put it.

IT depends to a certain extent on how much isolation you need. In extreme cases, you need a silencer on each side of the wall: one on the outer-leaf penetration, and one on the inner-leaf penetration. Or a single unit in the cavity between them that does both functions at once. For lower isolation needs, you can get by with just one silencer on each duct, and it can be either outside the outer leaf, or inside the inner leaf (in the room itself). As long as you design it as part of the overall isolation system, it can go wherever it fits best.

Speaker soffit wall and back wall corners are with bass hangers

Excellent! The only other comment I have is on your plan for diffusers on the rear wall: That might not be possible. The room seems to be borderline small for most types of diffuser. If they are numeric-sequence based diffusers (For example QRD, PRD, Skyline, binary pattern, etc.), then you need at least ten feet (about 3m) between the surface of the diffuser and the ears of anyone in the room who needs to do critical listening, and depending on the type of diffuser, and the frequencies to which it is tuned, you might need an even larger distance. Worst case, you could just put thick angled absorption there, perhaps with thin paneling or even widely spaced slats. Or maybe poly-cylindrical diffusers, Or a combination. In that case, you could do slot walls on the sides, to get a bit of diffusion like that. Nice space you have there! Very promising. If designed and built right, I'm betting you sure can hit your primary goal: "... a mix room that I can rely on to be of a very high standard acoustically". - Stuart -