"Ideal" Control Room Design

I have a studio design underway and am seaking broader based advice under a seperate topic. It appears that the control room acoustics are the most important to get right or at least to avoid major errors so I set out to create an optimized smaller control room design. It occured to me that certain rules of thumb are pretty widely accepted on this forum so if you start embedding them in your design and solve for the multiple variables, a good geometry should start to emerge. So far, the rules that I am trying to follow are: 30 degree speaker angles from the north (top, or forward of engineer) wall. Speaker firing position at 90 degrees from speaker soffit face. Engineer position at 38% from the north wall. Speaker axis at engineer ear position. Keep glass and doors out of the first reflection positions to allow proper treatment. Side walls splayed at 6% each for 12% total. Enough room for proper couch position and back wall treatment. Enough soffit depth and width for flush speakers and acoustic treatment. Questions: This results in a longer room than most I have seen including most of the John Sayer designs. Is the 38% rule for the engineer position good or should it be closer to the middle of the room? If so, the room would get wider in relation to length. What is a good rule for the north wall width. I have read 8' min from a number of posters. This would also widen the room. I have read that the length needs to be a minimum of X feet (seen 13 - 20') on its own. Also that you need a minimum square footage (seen 150 - 200 sq ft) or minimum volume (seen 1500 cubic ft). What is the advice here? Should any emphasis be put on trying to nail a good ratio (Bohner, et al) using average dimensions for this non-rectangle? Thats good for a start. After I nail these dimensions down I am going to move on to soffit detail, windows, doors, ceiling, treatments. BTW, I found a very good article at Micworks.com discussing this in detail and I created a professional level control room based on their "rules" which seemed credible (also attached).: http://www.micworks.com/freeinfo/basicdesign.htm It illustrates the challenge because this takes up a roughly 25' X 25' footprint which is the entire space budget for many studios (2 car garage). The question is how small can you go and still have a workable room. Thanks,

Speaker firing position at 90% from speaker soffit face.

'm not quite sure what you mean by that rule. The others seem basically OK, but that one threw me. Are you saying that the speaker should stick out of the soffit? The face of the soffit should be aligned exactly with the face of the speaker cabinet itself. The soffit panel acts as an infinite baffle, increasing the size of the front panel. Basically, the entire soffit unit becomes a new and much larger cabinet for the speaker. If that's not what you were talking about, then maybe you could explain more completely what you mean by that statement?

Engineer position at 38% from the north wall.

Ears. Room depth. You want your ears at 38% of the room depth, or 38% the distance between the front wall and rear wall. But that number isn't carved in stone: it's just a starting point, a guideline. You do not have to stick to it religiously.

Speaker axis at engineer ear position.

The speaker axes will intersect a bit behind your head, to exactly at your head, since the speakers are aimed such that the axes graze your ears.

Side walls splayed at 6% each for 12% total.

That's for flutter echo! You will probably need a larger angle if you want to create a proper RFZ design. The actual angle will depend on many factors: the only way to be certain is to ray-trace.

Enough soffit depth and width for flush speakers and acoustic treatment.

There should be no treatment on the soffit panel itself, and the soffit panel width needs to be substantially greater than the width of the original speaker cabinet.

This results in a longer room than most I have seen including most of the John Sayer designs.

It shouldn't. John doesn't always follow this "rule" with his designs, because he doesn't need to! He knows what he is doing, and can treat the room properly such that he can have the mix position at a different location. In any event, 38% is just a guideline. However, it's a good guideline, and unless you are as good as John at designing rooms, it would not be a good idea to move too much away from that, and certainly not move to the center of the room. At 50% of room depth, all modes either peak or null. Not a good place to have your head! But if you are getting rooms a lot longer than what you see here with your mix position at 38%, then you might not be figuring things correctly. Maybe you could show a diagram of your reasoning, in an example.

What is a good rule for the north wall width. I have read 8' min from a number of posters.

Not sure what you mean by that: What wall is the "north wall", and what do you mean by " 8' min"?

I have read that the length needs to be a minimum of X feet (seen 13 - 20') on its own. Also that you need a minimum square footage (seen 150 - 200 sq ft) or minimum volume (seen 1500 cubic ft). What is the advice here?

1500 ft3 is the ITU and EBU minimum recommendation for critical listening rooms. Figure height of 8 feet, that gives you roughly 188 square feet of floor area. Figure a decent ratio for that (Sepmeyer, Louden, Bohner, whoever you like), and your numbers are not far off.

Should any emphasis be put on trying to nail a good ratio

A little, not much. Ratios are over-rated. Stay away from the bad ones, get close to any of the good ones, and you'll be fine. - Stuart -

Soundman2020 wrote:

Speaker firing position at 90% from speaker soffit face.

'm not quite sure what you mean by that rule. The others seem basically OK, but that one threw me. Are you saying that the speaker should stick out of the soffit? The face of the soffit should be aligned exactly with the face of the speaker cabinet itself. The soffit panel acts as an infinite baffle, increasing the size of the front panel. Basically, the entire soffit unit becomes a new and much larger cabinet for the speaker. If that's not what you were talking about, then maybe you could explain more completely what you mean by that statement? Sorry, I had a typo. I meant that the speaker face is flush with and on plane with the soffit which is at a 30 degree angle in reference from the front (north) wall. How firm is the 30 degree angle? I have also seen 40 degrees.

Engineer position at 38% from the north wall.

Ears. Room depth. You want your ears at 38% of the room depth, or 38% the distance between the front wall and rear wall. But that number isn't carved in stone: it's just a starting point, a guideline. You do not have to stick to it religiously.

Speaker axis at engineer ear position.

The speaker axes will intersect a bit behind your head, to exactly at your head, since the speakers are aimed such that the axes graze your ears.

Side walls splayed at 6% each for 12% total.

That's for flutter echo! You will probably need a larger angle if you want to create a proper RFZ design. The actual angle will depend on many factors: the only way to be certain is to ray-trace. I understand the flutter echo benefit. I assumed that you are going to get first reflections to the mixing position that need to be attentuated with treatments for a RFZ outcome. Are you saying that a RFZ design has no first reflections getting to the mixing position and no treatments are necessary? That would need a substantial increase in angle and/or room width.

Enough soffit depth and width for flush speakers and acoustic treatment.

[/b]There should be no treatment on the soffit panel itself, and the soffit panel width needs to be substantially greater than the width of the original speaker cabinet.

This results in a longer room than most I have seen including most of the John Sayer designs.

It shouldn't. John doesn't always follow this "rule" with his designs, because he doesn't need to! He knows what he is doing, and can treat the room properly such that he can have the mix position at a different location. In any event, 38% is just a guideline. However, it's a good guideline, and unless you are as good as John at designing rooms, it would not be a good idea to move too much away from that, and certainly not move to the center of the room. At 50% of room depth, all modes either peak or null. Not a good place to have your head! But if you are getting rooms a lot longer than what you see here with your mix position at 38%, then you might not be figuring things correctly. Maybe you could show a diagram of your reasoning, in an example. I did attach a diagram. A few more rules might help to dial this in. What are your thoughts on distance form the mixing position to the speakers and minimum speaker seperation?

What is a good rule for the north wall width. I have read 8' min from a number of posters.

Not sure what you mean by that: What wall is the "north wall", and what do you mean by " 8' min"? The north wall is the top or front wall, shown as 6' in my attached drawing. Some have said that this wall needs a minimum width to properly handle first reflections.

I have read that the length needs to be a minimum of X feet (seen 13 - 20') on its own. Also that you need a minimum square footage (seen 150 - 200 sq ft) or minimum volume (seen 1500 cubic ft). What is the advice here?

1500 ft3 is the ITU and EBU minimum recommendation for critical listening rooms. Figure height of 8 feet, that gives you roughly 188 square feet of floor area. Figure a decent ratio for that (Sepmeyer, Louden, Bohner, whoever you like), and your numbers are not far off. No problem here as I am at around 240 sq ft. on the first pass and I assume that it only needs to get bigger. In the case of angled walls can you average the width and length or do ratios become irrelevant in such geometries (or too difficult to model for mortals)?

Should any emphasis be put on trying to nail a good ratio

A little, not much. Ratios are over-rated. Stay away from the bad ones, get close to any of the good ones, and you'll be fine. - Stuart -

I added an additional drawing to the original post which creates a control room based on some professional level guidelines from what appears to be a credible source. It shows the depth of the challenge because this room takes up a footprint of approximately 25 X 25' which is the entire space budget for many projects. The question is how small can you go and still have a workable room. At that point you can decide to "afford" the space or bail on the seperate control room. Thanks,

... which creates a control room based on some professional level guidelines from what appears to be a credible source.

George, the instructions on that web site you link to appear to be very old! They refer to LEDE as being the design of choice, and as having been discovered within "the last ten years". That would date the article back to the mid 1980's! (LEDE dates from the late '70s): So most of the information in that paper about 20 to 30 years out of date! A lot has changed in the world of acoustics in the past 30 years, and some of the information in that article is now known to be just plain wrong. Such as this phrase:

There is nothing in the literature to suggest that using two sheets of wallboard on each side of a double stud wall will improve low end rejection, although two 1/2 inchers or one 5/8 on one side would probably be good for two or three Db.

Today, there is a HUGE volume of research on exactly that, and the jury is in: you can build a great isolation wall from a couple of sheets of 5/8" drywall on each side of double studs, and you can get isolation of over 60 dB, even 70 dB, if you do it right. Take a look at IR-761, for example, or even the famous Wyle report from 1973: Many of the beliefs expressed in that article are totally put to rest, fully dead and buried, by those. The article also states, several times, that the amount of isolation needed between a live room and control room, is 28 dB! :shock: That's a little bit WORSE than you get from a standard 2x4 stud wall with 1/2" drywall on each side! Most modern building codes call for 40-something dB, or even 50-something dB, of isolation in apartment blocks, office complexes, etc. So saying that a studio only needs 28 db of isolation is waaaaay wrong! No studio that I know of has such incredibly low isolation. The best are in the 80 to 100 dB range, good ones around 60 to 80, and even home studios can realistically get at least 50, hopefully close to 70. I don't have the time (or the inclination) to go into all of the other issues with that article: suffice it to say that LEDE design has long since passed out of favor, and modern designs these days are based on the RFZ or CID concepts, which are similar to LEDE in some aspects, but vastly different in others. So some of the advice in that article is good, but other parts are simply no longer correct at all. Sorry, but I wouldn't use that article as the basis for a designing a modern studio.

It shows the depth of the challenge because this room takes up a footprint of approximately 25 X 25' which is the entire space budget for many projects.

With 625 square feet (roughly 50 m2) you can build a very decent sized control room, and a very decent sized live room, perhaps even with a small isolation booth thrown in, if you are lucky. ITU and EBU recommendations today call for a minimum control room volume of 1500 ft^3 (45 m3). Assuming 8 foot ceilings, you need a footprint of about 185 ft^2. So a room of roughly 12 x 15 would do that just fine, or any similar set of dimensions that is close to one of the good ratios.

The question is how small can you go and still have a workable room. At that point you can decide to "afford" the space or bail on the seperate control room.

While 1500 ft3 is the recommendation, there are numerous examples here on the forum (and elsewhere) of MUCH smaller studios that are highly successful. For example, this one, designed by John himself, fits inside a normal shipping container. http://www.johnlsayers.com/Studio/Pages/Container.htm The build thread is here: viewtopic.php?f=11&t=4168 The total interior volume of that container is only 1000 ft3, BEFORE treatment, but John even managed to split off a section for a tiny live room (big enough for drums!), so the final interior volume of the control room is probably less than half of the ITU / EBU recommendation. And how does that place sound? Well, the same guy commissioned John to do two more studios in containers afterwards, so I guess he was happy! And John even posted links of a stunning recording of "Danny Boy" done in one of those. Very impressive. So, can you build a studio in a tiny space? You bet! :) - Stuart -

Stuart Thanks, point made. I also appreciate the encouragement on the small control room design. I need guidance on a few basics to keep going. My assumptions (please comment if You dissagree): One of the goals in control room design is to achieve your acoustics performance goals without a dead room approach which is unatural and fatiguing to work in. This requires that reflections still remain but are managed to maintain imaging and clarity. All first reflections off of the front and side walls do not need to be redirected with the wide and deeply angled side walls of a large design, you can handle those with acoustic panels to reduce their levels adequately. No first refections that are within 20ms of the arrival of direct path sound. This means that your fastest remaining first reflection (back wall) has to be at least 11 feet from the mixing position and with that position at 38% from the front wall, the room length needs to be at least 18 feet. This is one of the goals that I still can not rationalize if a successful smaller control room is possible. Splayed side walls at 6 degrees each or more will help to reduce flutter echo but you can take or leave this design feature because you can also solve this problem with treatments. A properly executed soffit design is essential for proper perfomance using far field monitors. Lastly, do you need to switch to near field monitors when the room gets below a certain size/length? Thanks,

One of the goals in control room design is to achieve your acoustics performance goals without a dead room approach which is unatural and fatiguing to work in. This requires that reflections still remain but are managed to maintain imaging and clarity.

Exactly! Dead rooms are uncomfortable. There are specific recommendations for reverberation times in each frequency band, for different sizes of room and different types of music.

All first reflections off of the front and side walls do not need to be redirected with the wide and deeply angled side walls of a large design, you can handle those with acoustic panels to reduce their levels adequately.

You are talking about an RFZ design: Reflection Free Zone. That's the modern concept: design the room to keep all first order reflections away from the mix position. However, there are limits as to what can be accomplished just with geometry, and some type of treatment on first reflection points is often still needed. But unlike the article that you originally linked too, putting diffusers on the first reflection points is no longer considered a good idea for most rooms, especially small ones. Absorption is one possibility, slot walls are another.

No first refections that are within 20ms of the arrival of direct path sound. This means that your fastest remaining first reflection (back wall) has to be at least 11 feet from the mixing position and with that position at 38% from the front wall, the room length needs to be at least 18 feet. This is one of the goals that I still can not rationalize if a successful smaller control room is possible.

That's because later research has shown that the original "20/20" criteria is too strict. It wasn't just 20ms, but also 20 db down. In other words, the first reflections that did arrive at the mix position after 20 ms were also supposed to be attenuated by 20 dB. That's not easy to accomplish, and later psycho-acoustical research showed that 15/15 is more realistic (15 ms delay, 15 dB down), and even 10/10 is still acceptable. so if you can get your first reflections to stay away for at least 10 to 15 ms, and then be at least 10 to 15 dB lower than the direct signal, you can get decent acoustics. A drop of 10 db on the first reflections is, subjectively, half as loud, which is enough to keep the brain happy. And a delay of 10 ms doesn't quite meet the Haas time limit, but seems to be good enough for most. So 6 feet from head to rear wall is reasonable, giving a room length of 9 to 10 feet. Now that is real tight, and also isn't easy to do, but is a LOT more realistic for average home studios. However, having said that, you'll see that many of John's designs use a really deep bass trapping system on the rear wall, for the precise reason of keeping those early reflections down even lower in level, and relying more on the reflections from the side walls to fill in the resonant field, instead of the back wall. That makes the path for the first reflections much longer, and attenuates the level even more. The point is, with good design you CAN use a small room adequately. Of course, it will never be as good as a large room, due to other factors (lack of a real statistical resonant field, for starters, lack of support for low frequency modes, etc.) but it can still be pretty darn good.

Splayed side walls at 6 degrees each or more will help to reduce flutter echo but you can take or leave this design feature because you can also solve this problem with treatments.

Yup! Splaying side walls 6° will not give you an RFZ (unless you have a really wide room!), but it will control flutter. And as you say, flutter can usually also be controlled with treatment. But splaying more than that will give you RFZ. How much more? Depends on the room, and the design. You have to ray-trace each case to find out.

A properly executed soffit design is essential for proper perfomance using far field monitors.

There is no far field in a small room! Pure marketing. On another thread I wrote an explanation of near-field / far-field just a few days ago, but basically the issue is this: there are two definitions for what "near field" means. One relates to the speaker alone when tested in free space (no room around it). The other relates to each individual room, regardless of the speaker. So what happens when you put a speaker in the a room? Which near field wins? It's complex, but basically the room wins. The room acoustics override the speaker. So ANY speaker in a small room is a near-field speaker, simply because the room is not big enough to even have a "far field". There is a point, called the critical distance, at which there is a transition from near field acoustics (6 db or more drop per distance doubling) to far field (3db or less drop per distance doubling). For the average room, the critical distance is really, really close to the rear walls, and very often is actually on the other side of the wall in reality. so even if you buy a far-field monitor, it will technically and actually be near field monitor in any average home studio. Then there's the issue of "RT-60", which many people still seem to consider valid for a small room: it isn't. Technically, the critical distance is the transition from the speaker direct sound being dominant, to the room's reverberant field being dominant. Small rooms do not have a reverberant field! You need large dimensions to be able to establish a statistically valid reverberant field: around 7 times the lowest wavelength of interest. do the math: for a 20 Hz wave, that's a really large room! What you actually measure in a small room is not the reverberant field, but the modal behavior. The dips and peaks on your waterfall plot for the low end are very likely to be modal issues, or reflections, and not true reverb at all. So there just isn't any "far field" in a small room. And of course, there isn't any such thing as a "mid-field" monitor. That's just marketing hype.

Lastly, do you need to switch to near field monitors when the room gets below a certain size/length?

Near / far field is a function of room volume and dimensions, as well as treatment to a certain extent, so the height does play a part, to a certain extent. But unless you have a pretty large room, you can't actually have a far field inside the room anyway, as mentioned above. So just get good near field monitors, and soffit mount them. Despite common myths, most near fields can be soffit mounted, if done right. Soffit mounting provides so many benefits that it is well worth doing, even in a small room. Perhaps that should be "especially in a small room"! - Stuart -

Stuart Thanks for all of the great info. Based on your feedback, I have decided to try designs where all of my rooms are rectangles since in small room modes are dominant, flutter echo can be treated, 6% walls don't remove first reflections through geometry in the control room, and the matching 6% wall in the live room has little or no benefit. In a rectangular room I can make certain that I have good ratios without the controversy of average dimensions and their validity in modal distribution assumptions. Make the control room and live room 1500 cubic feet or larger. Use Bohner or one of the top 3 Louden or Sepmeyer ratios. Maintain the mixing position at 38% from the front wall and angle the soffit walls as needed. Place the bathroom and HVAC rooms across the hall on an outside wall. I tried 2 approaches, one with a smaller control room meeting the minimum volume suggestion of 1500 cubic feet and a second layout with window line of sight to all rooms and a bigger control room. Comments? Thanks,

In a rectangular room I can make certain that I have good ratios without the controversy of average dimensions and their validity in modal distribution assumptions. ... Use Bohner or one of the top 3 Louden or Sepmeyer ratios.

You don't need to get too tied up on ratios: they are not the be-all and end-all of studio construction. They are just guidelines, tools. Use them to stay away from bad ratios, get close to a good one, and leave it at that. There's no need at all to try to refine your ratio to perfection. Ball park is good enough. And there really isn't much controversy over the validity of averaging rooms with slightly angled walls: it is valid to do so. Everest himself says so, in "the Bible".

Maintain the mixing position at 38% from the front wall ....

Once again, you don't need to go crazy about the 38% figure. It, too, is just a guideline, a starting point. You might end up at 36% or 41% or whatever. Once again, the idea is to stay away from bad places in the room (50%, 25%, etc) and get close to the good place. If you think about, just leaning back or forward a bit in your chair in a small room is going to move your ears several percentage points! The engineer will most likely simply slide his chair back/forth into the best location anyway, either consciously or subconsciously. These "rules" are only meant to get you in the right track.

... and angle the soffit walls as needed ...

If you do the layout correctly, that angle should end up such that the acoustic axes of the speakers intersect a few inches behind the head of the engineer, at an angle of 60 degrees (minimum) and up to 90° (maximum).

I tried 2 approaches, one with a smaller control room meeting the minimum volume suggestion of 1500 cubic feet and a second layout with window line of sight to all rooms and a bigger control room.

#4 is better, in my opinion, but there are many ways that both layouts could be improved. For example, you have created practical problems with that design: to get from the control room to any of the other rooms requires a long walk, and to get to the either the iso booth or the vocal booth you have to go through the control room. The iso booth is a real long way away... You also do not have good sight lines in either design. Even in #4, you can only see less than a quarter of the live room from the mix position, and you cannot see into the vocal booth or the iso booth at all! You also seem to have your inner leaf coupled to your outer leaf, and you are missing doors in places... While I agree that splaying walls at only 6° is not really necessary, and that it is easier to predict modal response with rectangular rooms, to me it makes so much sense to splay the walls for at least the front half of the room, to get a proper RFZ design. It also gives you other advantages that you don't have with rectangular rooms, such as better sight lines to the rooms on each side, and better use of space. But that's just my personal view: others prefer rectangular rooms, and either way will work, if it is designed right. - Stuart -

I see that I need to clean up a few walls and doors, thanks. I see the appeal of sliding doors in some respects because you can accomplish the window function and have direct transition between the live room and control room. I for one dont like sliders so i did not use them in my designs. Given that and assuming that doors have to stay out of the back wall and the near sides (bass traps and reflection control), the front wall, and first reflection points on the side walls, the window location, there is only one place left in the control room. Do you have a different of view of these points? I will generate a splayed wall CR to get a RFZ design using soffit mounted near field monitors. A first pass shows that 12 degree splayed walls should do it which would result in a single splayed wall in the live room of 12 degrees (might fix the door problem as well). Is that single LR wall angled enough to be worth losing the accurate mode calculations of a rectangular room? Are the soffit walls reflective surfaces or transparent in my raytrace analysis for a RFZ design? What guidance can you give me on direct speaker distance to the mixing position and speaker seperation for soffit mounted near fields? What sized mixing desk should I assume for raytracing in todays digital world? Thanks,

I see the appeal of sliding doors in some respects because you can accomplish the window function and have direct transition between the live room and control room. I for one dont like sliders so i did not use them in my designs.

Sliding doors of the type you need for a studio are also pretty expensive! Plus, the actual opening isn't any bigger than an ordinary hinged door. They look great, but they do have their drawbacks.

Given that and assuming that doors have to stay out of the back wall and the near sides (bass traps and reflection control), the front wall, and first reflection points on the side walls, the window location, there is only one place left in the control room. Do you have a different of view of these points?

I'd agree that the room corners are not great places to put doors, but all of the walls are potential candidates. You can put a door in the front or rear wall, if you do it right. And if you have absolutely no choice (existing structure that cannot be modified, for example) then you can even put them in the corners, and treat them suitably.

I will generate a splayed wall CR to get a RFZ design using soffit mounted near field monitors.

The soffit is only part of RFZ design: you will most likely need angled side wall extensions to complete the picture, which is kind of what splayed walls are anyway. Plus, if your room is wide, your geometry might not work out if you don't splay the side walls, at least the front half of the room.

A first pass shows that 12 degree splayed walls should do it

You cannot angle a soffit at 12 degrees! That would be force your mix position practically all the way to the front wall! Your soffit might be angled 30 to 60 degrees, but never less than 30. You cannot get the speaker geometry correct for angles much less than 30°.

Is that single LR wall angled enough to be worth losing the accurate mode calculations of a rectangular room?

I guess that depends on what you mean by "enough"! :) The thing is, even a tiny angle forces changes in modal behavior. The changes, of course, are also tiny. The question is, how big an error are you willing to accept in your calculations? Is a 5% error OK (meaning that a mode predicted to be at 100 Hz will actually be at 105)? How about 20%? That's the issue. How big of an error can you handle? And does it matter? The reason I bring that up is because too many people get caught up on trying to predict perfect ratios and perfect dimensions, but in reality the actual room they build will not match predictions very well anyway. The simple act of putting a person, a speaker, a mic and some equipment in the room will already skew the actual response slightly, even assuming that, by some miracle, they were able to build the room with millimetric precision, and perfect right angles. (Personally, I never met a builder who could do that, and have no idea where you would find such perfect building materials anyway, but that's another story...). So the room will never actually behave the way it was predicted. Add some furniture, and some equipment, and you change it even more. The point is this: before you treat the room, you have to do a full acoustic analysis on it anyway! You need to find out how it is ACTUALLY behaving, in reality, not how it was predicted to behave. Based on that, you can design the treatment. So no matter how good your ratio is, or how well you build, you'll still need to measure in order to treat. So there really is no need to go crazy with ratios. If you pick a basic rectangular shape that is close to a good ratio, then splay the walls as needed to get an RFZ while also keeping roughly the same total volume, then you won't produce a monster: it won't be too far off the prediction (unless you start angling walls ridiculously!). The point of modal analysis is to stay away from really bad situations, get in the ball park of a good one, then measure and treat accordingly.

Are the soffit walls reflective surfaces or transparent in my raytrace analysis for a RFZ design?

ALL large surfaces with a bit of mass in the room are acoustically reflective. That includes soffits, desks, consoles, racks, keyboards, doors, windows, sofas, people, chairs, etc. The question is: how much of which frequency does each one reflect? The more massive (weight) and rigid it is, then lower and better it will reflect. Larger surface reflect lower frequencies. In general, a wave will ignore anything smaller than its own dimensions (quarter wave), so waves wrap around things that are smaller than they are, and bounce of things larger than they are. They reflect less of thin, soft surfaces, and more off thick hard surfaces. High frequencies reflect even off thin things, but low frequencies go right through. Etc. Low frequencies are non-directional and spread out spherically, high frequencies act more like rays, and travel in straight lines. Low frequencies "bounce" along large wave fronts at different points, while high frequencies are more specular in their reflection. Etc. There's a lot of things to consider! But basically, yes, your soffit panels are highly reflective across a large part of the spectrum. That is, in fact, their purpose: the become the new front panel of the speaker, emulating an infinite baffle. Which will lead you to the conclusion that simply putting soffits across the corners of your room is exactly the same as splaying your walls: it makes your room non-rectangular, and therefore unpredictable using the normal equations. The soffits ARE the two new diagonal walls of the room! The original walls behind them become invisible to most wavelengths (except for very long ones). So if you put soffits in your room, you have a six-sided room, and any modal analysis you do on it will be inaccurate anyway. That's another reason why trying to finesse a "golden ratio" is pointless: Anything at all that you put in the room changes the behavior in one way or another.

What guidance can you give me on direct speaker distance to the mixing position and speaker seperation for soffit mounted near fields?

For every room there is a distance from the speaker, called the "critical distance", at which the direct field from the speakers is exactly balanced by the reverberant field of the room itself. If you are closer to the speaker than the critical distance, then you are in the direct field or "near field" of that room, REGARDLESS OF WHAT SPEAKER YOU USE, WHO MADE IT, OR HOW MUCH YOU PAID FOR IT!. The critical distance depends mainly on room volume, dimensions and construction materials. I seem to be making this point repeatedly of late (not just to you! It has come up a number of times of the last few weeks). You can put a speaker that calls itself "near field" or "mid field" or "far field" or "really, really, distant super magical extreme field", and it makes no difference: It is the ROOM, not the speaker, that determines where the direct field ends and where the reverberant field begins. (Eric, if you are reading this, OK, I'm ignoring Q here, but you get the point, I'm sure...) Pretty much any good studio monitor these days will merge their tweeter and woofer fields nicely in a short distance, much less than a meter, so saying that a speaker is good for "near field" monitoring these days is pretty meaningless: as long as you are not so close that can hear the tweeter and woofer fields separately, then you are at a good distance. In other words, the tags "near field monitor" and "far field monitor" don't mean a lot these days. They could equally well be called "big speaker" and "small speaker", and mean the same. (And of course the term "mid field" is pure marketing hype: technically, there is no such thing, and even if there was, why would you want to listen in the middle of a transition zone?) OK, so that's a preamble for this: Your head needs to be far enough away from the speakers that you get a fully merged woofer/tweeter sound field, but not so far away that you are beyond the critical distance for the room. For most speakers and most rooms, that means you need your head to be at least 1 meter from the speakers, and no further way than the walls! Yup, in a small room there is no reverberant field at all, so the critical distance is technically at some point beyond the walls.... In other words, get your head at least a meter away from the speakers, maybe 2m or even 2.5m if your room is big enough. Beyond that doesn't make much sense, ITU and EBU recommendations for critical listening rooms are in that range. Arrange the speakers roughly equidistant from the room center line and the side walls, and angle them to point at your ears when seated at the the mix position. They should be roughly the same distance apart as they are from your head. So if you have them 2m from your head, they should also be about 2m away from each other. The match here isn't carved in stone, so you might have them 2m apart and only 1.80 me from your head, for example. But what IS critical, is symmetry: your head MUST be on the center line, and the speakers MUST be the exact same distance from your head, and from the side walls. so if the left speaker is 1.87m from your head and 1.03 m from the left wall, then the right speaker must also be 1.87m from your head and 1.03m from the right wall. This is really, really important for perfect stereo imaging, accurate sound staging, phantom center, etc. If you want to go crazy about one point in your studio, this is it. Forget ratios: worry about symmetry and precision alignment of your speakers. Here's one more to add to the equation: With all this in place, your ears should be roughly 38% of the distance from the front wall to the rear wall. "ROUGHLY" is the operative word! Not written in stone. Like ratios, this is just a guideline.

What sized mixing desk should I assume for raytracing in todays digital world?

What size console will you be using? That's the size desk you need. If you will be doing pure ITB, no console, then make the desk as small as you can to still hold your mouse, keyboard, video monitors and coffee mug. The reason, once again, is first reflections: desks and consoles are in the perfect place for being first reflection points. so if you need a big desk, then consider tilting the surface slightly to minimize reflections, or place it carefully in relation to your head and the speakers to avoid / minimize reflections. --- OK, now that is all out of the way: What I was trying to say yesterday is that your room distribution can be improved considerably. Try putting your control room in the middle, and spreading the other rooms around it. Splay the walls enough and you can get good sight lines out the front side walls, and still have space for doors in the rear side walls, with good modal behavior, and room for treatment at the rear, sides, top, front .... 'nuf said! :) - Stuart -

Wes Lachot, the man that uttered the now viral myth about 38% speaker placement should be an absolute read. On that note I point you to his site http://weslachot.com/pub5.html , well, his site but to a specific article in Tape-op where Wes talks about, basically what we are talking about, the failures that happened, how he wanted to improve...kinda like John Sayers I would assume. At one time there was a page on his site that discussed his idea and approach to the 38% placement he uses as a "starting" position for monitors in a control room. I cannot find it...and I could not even locate it at my site buildthisroom.com , here today gone tomorrow. In any event, OP, there are more things that you are in danger of doing wrong than just your speaker placement and 6 degree splays on your walls. This aspect of acoustics can be kind under the skilled hand that has knowledge, and has been proven to be a disaster under the guidance of the uncertain armed with obsolete data and aided by unskilled technicians. Good luck and Happy New Year,

I still was not able to get the words directly out of the Authors mouth, but I did find the link on buildthisroom.com I was looking for. It points to : http://forum.studiotips.com/viewtopic.p ... =guideline Eric Desart moderates the thread with a host of high level acoustical guys. enjoy, it's nine pages long :)