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naethoven
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2nd June 2009
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Quote:
Originally Posted by Wes Lachot View Post
Nathan,

The ratios you mention are better (1 : 1.4 : 1.66) than what you had. You are actually is the neighborhood of a set of ratios that are among the very best, namely 1 : 1.26 : 1.59 (or 1.6). These ratios represent an augmented triad, which by definition is the most evenly spaced sequence possible for the low frequencies. I don't know if those ratios are practical for you or not, but it would be worth checking out.
1:1.26:1.59 looked good to me and will fit my space just fine, but 1:1.4:1.66 yields 300sqft more volume. That is the only reason I chose it over the augmented triad. Would it be better to go for more volume or more accurate modal spacing?


Quote:
Originally Posted by Wes Lachot View Post
There won't be any holes in the low frequencies with these ratios...
You mean with my latest (1:1.4:1.66) or with the augmented triad?
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3rd June 2009
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Nathan,

Neither ratio set should have significant holes, but the augmented ratios have a maximum spacing of 4 half steps, while the other set has a maximum spacing of 6 half steps. So in that sense the 1 : 1.26 : 1.59 is better.

I think you meant to say cu.ft., not sq. ft. It's tough at this size, and it's probably a toss-up. I'd probably do the same thing and go with the larger cubic volume. I'd say go for the 1 : 1.4 : 1.66 and don't look back.

--Wes
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3rd June 2009
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Quote:
Originally Posted by Wes Lachot View Post
Nathan,

Neither ratio set should have significant holes, but the augmented ratios have a maximum spacing of 4 half steps, while the other set has a maximum spacing of 6 half steps. So in that sense the 1 : 1.26 : 1.59 is better.

I think you meant to say cu.ft., not sq. ft. It's tough at this size, and it's probably a toss-up. I'd probably do the same thing and go with the larger cubic volume. I'd say go for the 1 : 1.4 : 1.66 and don't look back.

--Wes
You're right I did mean cu.ft (a misprint!). Thank you so much for all of your frank and informative responses. You've opened me up to a whole new way that math/music/architecture/physics works together- How indicative of our Creator. I very much enjoy learning new things about physics, especially physics of sound and music, and I have debated getting a Master's in Acoustics. So thank you very much!

I will plan on the 1.4:1.6 ratio and will post my new diagram ASAP. If you could please check back and give a critique of the new plan it would be much appreciated!!

So I take it I don't need to be concerned with the 80Hz dip in the Bonello graph of the 1:1.4:1.66??

Many thanks,
Nathan Webb
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3rd June 2009
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Don't over-think the ratio. Yes, it is the basis of a good room, and an important early choice to make. However, there are many other factors to consider, and if you are going to properly treat the room, then the choice between these two ratios won't end up making that big a difference in the end. If a room is too small, even if it technically has a slightly better ratio, it can still often be a worse room.

Add to that practical concerns (fitting gear and people, systems, support spaces), ergonomics, listening position, room to get free standing monitors away from boundaries (if that's monitor choice), needing to be 3 wavelengths from diffusion if you plan to use any etc...

If you really want to take everything into account, some ratios end up working better in larger rooms, some in smaller rooms, and then there are variables when you have absorptive treatments. For example, surface impedance can affect phase and magnitude, not just magnitude, and this obviously can have an impact.

You can't take a ratio in isolation, any more than you can take any other element of an acoustical design in isolation. The difference between those two ratios is somewhat insignificant in the context of the rest of the variables. Pick the one that works best for the whole plan, and don't sacrifice a bunch things just to make the room mode graph look nice.
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3rd June 2009
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Quote:
Originally Posted by jayfrigo View Post
Don't over-think the ratio. Yes, it is the basis of a good room, and an important early choice to make. However, there are many other factors to consider, and if you are going to properly treat the room, then the choice between these two ratios won't end up making that big a difference in the end. If a room is too small, even if it technically has a slightly better ratio, it can still often be a worse room.

Add to that practical concerns (fitting gear and people, systems, support spaces), ergonomics, listening position, room to get free standing monitors away from boundaries (if that's monitor choice), needing to be 3 wavelengths from diffusion if you plan to use any etc...

If you really want to take everything into account, some ratios end up working better in larger rooms, some in smaller rooms, and then there are variables when you have absorptive treatments. For example, surface impedance can affect phase and magnitude, not just magnitude, and this obviously can have an impact.

You can't take a ratio in isolation, any more than you can take any other element of an acoustical design in isolation. The difference between those two ratios is somewhat insignificant in the context of the rest of the variables. Pick the one that works best for the whole plan, and don't sacrifice a bunch things just to make the room mode graph look nice.
Absolutely! Excellent post!

Ratios, while being significant, certainly aren't at the top of my list... Just pick a decent one and move on.

As Jay points out, once you start treating and shaping your room, the variables are going to change/evolve anyway.
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3rd June 2009
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Quote:
Originally Posted by jayfrigo View Post
Don't over-think the ratio. Yes, it is the basis of a good room, and an important early choice to make. However, there are many other factors to consider, and if you are going to properly treat the room, then the choice between these two ratios won't end up making that big a difference in the end. If a room is too small, even if it technically has a slightly better ratio, it can still often be a worse room.

Add to that practical concerns (fitting gear and people, systems, support spaces), ergonomics, listening position, room to get free standing monitors away from boundaries (if that's monitor choice), needing to be 3 wavelengths from diffusion if you plan to use any etc...

If you really want to take everything into account, some ratios end up working better in larger rooms, some in smaller rooms, and then there are variables when you have absorptive treatments. For example, surface impedance can affect phase and magnitude, not just magnitude, and this obviously can have an impact.

You can't take a ratio in isolation, any more than you can take any other element of an acoustical design in isolation. The difference between those two ratios is somewhat insignificant in the context of the rest of the variables. Pick the one that works best for the whole plan, and don't sacrifice a bunch things just to make the room mode graph look nice.
Sounds like very good advice from you and Northward. This clears up a lot of things for me. Thank you! I will post my new design some time today. Please check back and critique it if you have the chance.
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great stuff going on in here. subscribed
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New Design

Alright guys, here it is. My CR based on 1:1.4:1.66 Again, please tear it apart!!! ANY problems you see I want to know about!

(I do intend to add lots more acoustic treatment, the existing treatment is just thrown in for spacing purposes.)
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Angles of Control Room walls-cr-top-view-1-14-166.jpg  
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regarding ratios:

you did account for the area of the bass trap in your length yes?

for the angled walls, your width is an average?

is the ceilng sloped, and if so, again...averaged?
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4th June 2009
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Quote:
Originally Posted by dykstraster@gmai View Post
regarding ratios:

you did account for the area of the bass trap in your length yes?

for the angled walls, your width is an average?

is the ceilng sloped, and if so, again...averaged?

Yes.
Yes.
and Yes!

But thank you very much for looking out!

Wes, Andre, Jay, any thoughts? Does anything not look right to you?
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4th June 2009
Old 4th June 2009
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Quote:
Originally Posted by naethoven View Post
Alright guys, here it is. My CR based on 1:1.4:1.66 Again, please tear it apart!!! ANY problems you see I want to know about!

(I do intend to add lots more acoustic treatment, the existing treatment is just thrown in for spacing purposes.)
Nathan,

Two things jump out at me. One is that I think I detect glass on the left front wall. That would not be a great thing given the angle of the wall - you are going to get reflections at the mix position. Or maybe it's not glass; I'm assuming it is because it's blue.

The other thing is that it looks like you have a roughly 3 ft. deep bass trap in the rear of the room, and the seating position looks like it's 6 ft. or so from the back wall. From my experience, you are going to get a wicked null at around 47 Hz on the couch, if you locate the couch there, despite the deep bass trap. I usually place the couch much closer to the back wall, because that's how we get the best results. That way the rear wall null is up over 240 Hz or so (above the first 2 1/2 bass octaves), and the clients on the couch can judge the kick and bass much better. We use other trapping techniques so that we don't have to place the rear couch so far out.

Of course there are many ways to approach control room design. This is what we've found works best within our method of building rooms.

--Wes
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4th June 2009
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Quote:
Originally Posted by Wes Lachot View Post
Nathan,

Two things jump out at me. One is that I think I detect glass on the left front wall. That would not be a great thing given the angle of the wall - you are going to get reflections at the mix position. Or maybe it's not glass; I'm assuming it is because it's blue.

The other thing is that it looks like you have a roughly 3 ft. deep bass trap in the rear of the room, and the seating position looks like it's 6 ft. or so from the back wall. From my experience, you are going to get a wicked null at around 47 Hz on the couch, if you locate the couch there, despite the deep bass trap. I usually place the couch much closer to the back wall, because that's how we get the best results. That way the rear wall null is up over 240 Hz or so (above the first 2 1/2 bass octaves), and the clients on the couch can judge the kick and bass much better. We use other trapping techniques so that we don't have to place the rear couch so far out.

Of course there are many ways to approach control room design. This is what we've found works best within our method of building rooms.

--Wes
Wes,
Thank you so much for your frank and applicable advice. That is glass in the front left side (windows are blue, doors are tan). I put glass there so I could have line of sight w the studio. I debated that heavily but I couldn't really think of any other way to have lin of sight with that corner. Would it be enough to hang absorbtive treatment at the first reflection on the glass, but still have the glass there to see around the panel? Or maybe I could take the panel down during tracking and put it up to mix? Maybe I should just make the window outside of the first reflection range (for all listening positions) and deal with not having direct line of sight w that corner. I could still see a good portion of the studio space. If I angle the glass toward the floor, wouldn't that direct the reflections to the floor and away from mix pos?


As for the bass trap in the back, I don't have to have that there at all. Just throwing ideas around.
Quote:
Originally Posted by Wes Lachot View Post
you are going to get a wicked null at around 47 Hz on the couch, if you locate the couch there, despite the deep bass trap. I usually place the couch much closer to the back wall, because that's how we get the best results. That way the rear wall null is up over 240 Hz or so (above the first 2 1/2 bass octaves),
We know this because the 2nd harmonic's null is at 1/2 the length of the room, 3rd harm's nulls are at 1/3 the length, 4th harm's nulls are at 1/4th etc. Correct? So it's better to have the couch closer to the back wall because there the nulls are at higher frequencies, correct? I just want to make sure I'm understanding the theory correctly.
Yes, I can definitely scratch that 3' trap, just trap the corners, and maybe put a 1.5' deep trap in the ceiling. Thank you for that call.

Any further thoughts?
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4th June 2009
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Quote:
Originally Posted by naethoven View Post
Wes,
Thank you so much for your frank and applicable advice. That is glass in the front left side (windows are blue, doors are tan). I put glass there so I could have line of sight w the studio. I debated that heavily but I couldn't really think of any other way to have lin of sight with that corner. Would it be enough to hang absorbtive treatment at the first reflection on the glass, but still have the glass there to see around the panel? Or maybe I could take the panel down during tracking and put it up to mix? Maybe I should just make the window outside of the first reflection range (for all listening positions) and deal with not having direct line of sight w that corner. I could still see a good portion of the studio space. If I angle the glass toward the floor, wouldn't that direct the reflections to the floor and away from mix pos?


As for the bass trap in the back, I don't have to have that there at all. Just throwing ideas around.

We know this because the 2nd harmonic's null is at 1/2 the length of the room, 3rd harm's nulls are at 1/3 the length, 4th harm's nulls are at 1/4th etc. Correct? So it's better to have the couch closer to the back wall because there the nulls are at higher frequencies, correct? I just want to make sure I'm understanding the theory correctly.
Yes, I can definitely scratch that 3' trap, just trap the corners, and maybe put a 1.5' deep trap in the ceiling. Thank you for that call.

Any further thoughts?
Nathan,

I try to never put glass in the front first reflection areas. If it's possible to have reasonable sight lines some other way, I would do it. If there's no other way, this is the sort of thing that would get me thinking that maybe I wasn't approaching the overall design problem from the best possible angle.

The reason for the rear wall-induced nulls I was describing is boundary interference as opposed to modal interfence (modal interference is a specific subset of the more general boundary interference). Your seating distance from the back wall is one of the most critical considerations in any room design, since the rear wall reflections are so destructive. This is because the rear wall is in the direct line of fire of the speakers.

Wes
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Wes,

After my last post, I remembered another reason for the distance I had chosen from the back wall. I reviewed a paper from the EBU entitled "Subjective assessment of audio quality - the means and methods within the EBU" I'm sure you may be familiar with it, it describes several criteria for a room to have good listening conditions. One of the conditions was that all listening positions should be at least 1.5m (4.92ft) from the back and side walls. What would you suggest as an acceptable distance from the rear wall, and how do I deal with the boundary interference? Can you direct me to a paper to study?

Also, are you familiar with Sketchup? I am working w the design to determine the first reflection points and I am trying to find a quick and easy way to find a "angle of incidence=angle of ref" without just randomly guessing with the protractor! Also what about angling the glass down, to aim the ref at the floor?

Thank you,
Nathan Webb
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Quote:
Originally Posted by naethoven View Post
Wes,

After my last post, I remembered another reason for the distance I had chosen from the back wall. I reviewed a paper from the EBU entitled "Subjective assessment of audio quality - the means and methods within the EBU" I'm sure you may be familiar with it, it describes several criteria for a room to have good listening conditions. One of the conditions was that all listening positions should be at least 1.5m (4.92ft) from the back and side walls. What would you suggest as an acceptable distance from the rear wall, and how do I deal with the boundary interference? Can you direct me to a paper to study?

Also, are you familiar with Sketchup? I am working w the design to determine the first reflection points and I am trying to find a quick and easy way to find a "angle of incidence=angle of ref" without just randomly guessing with the protractor! Also what about angling the glass down, to aim the ref at the floor?

Thank you,
Nathan Webb
Nathan,

There is a wealth of helpful information in the EBU paper, but the authors don't give any justification for this recommendation that "all listening positions should be situated at least 1.5 m from the side walls and the back wall of the room".

There's no detail on what type of room they are talking about for starters, and I will grant that it is true that in most listening rooms the bass build-up at the walls is pretty horendous. But if you've never experienced the sound at the rear couch of a nicely done control room, I can tell you that it can be a fairly accurate place to listen. The side walls have to be properly treated, of course. But the bass response back there, while maybe up a few dB, will tend to be flatter than it is in intermediary positions between the rear of the room and the engineer's position.

Wes
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Quote:
Originally Posted by Wes Lachot View Post
Nathan,

There is a wealth of helpful information in the EBU paper, but the authors don't give any justification for this recommendation that "all listening positions should be situated at least 1.5 m from the side walls and the back wall of the room".

There's no detail on what type of room they are talking about for starters, and I will grant that it is true that in most listening rooms the bass build-up at the walls is pretty horendous. But if you've never experienced the sound at the rear couch of a nicely done control room, I can tell you that it can be a fairly accurate place to listen. The side walls have to be properly treated, of course. But the bass response back there, while maybe up a few dB, will tend to be flatter than it is in intermediary positions between the rear of the room and the engineer's position.

Wes
Wes, when you say back of the room, you do mean close to the REAL/rigid wall, not the false back wall with 4 ft of hangers behind it, correct? How far away from the back wall?

And what about just angling the glass at the floor to handle the HF ref?
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New diagram

Here is my latest. I just left off the treatment for now, just focusing on the shape and placement of things right now. I moved the couch back, readjusted the angles of the front wall and located the 1st ref points to treat for RFZ. I plan to start my glass AFTER these points of treatment, extending from there toward the back wall.

Do I need to be concerned with the 1st reflections reaching the couch (about 14 ms total travel time, not 14 later than direct)? How do I address these?

Can you please teach me about the critical distance where reverberant sound = direct, and what the importance of it is? What do I do with it?

Thank you
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Can you please teach me about the critical distance where reverberant sound = direct, and what the importance of it is? What do I do with it?
Don't worry about critical distance in a small room like this, especially with the treatments likely to go into a studio control room build. You really don't get much of a reverberant field (or statistical sound field) in such a small, absorptive room. It's effectively direct field anywhere you are likely to put your ears.

If you really want to calculate it, the formula is rc=square root of R/16(pi)D.

The "c" is really a subscript, meaning critical, and r means distance. This is because point sources spread spherically; the source is at the center, and the sound expands like a balloon being blown up. This means that a radius on the sphere is equal to the distance from source to receiver (listener). So r, or radius, always refers to distance.

So, r(sub)c is the critical distance - where the direct field and reverberant field meet, and the direct sound and reverberant sound are equal. Beyond the critical distance from the source, you are in the reverberant field and hear a greater proportion of reverberant sound to direct sound. Closer to the source than the critical distance, you hear more direct than reverberant. The direct field is essentially a bubble around the source. The distance is like a sphere around the point source. It's not like it's a straight line across the floor.

Inside the square root you get R (capital R this time) which is the Room Constant, divided by 16 times pi (3.14 etc.) times D, which is the directivity factor of the source. Optionally you can use "Q" which goes in the numerator instead of the denominator. Q = 4 equates to D = 1/4. The accepted Directivity factor for human speech is 1/2, or in the case of the math, a decimal value of .5 because you can't have a fraction in a fraction. For your source, you would need to know the directivity of your speakers, and if it changes significantly with distance in case the relevant distances make a difference. You also need to consider that you have two speakers radiating rather than a single source.

Next, you'll need to calculate the Room constant. You can do this with the equation R=A(sum)s/(sum)s - A, where A is the total absorption in sabins, and (sum)s, or greek symbol "sigma" s is the sum of the surface areas. This is the total area of all 4 walls plus ceiling and floor, or in your case, sum of each angled surface since it's really more than 4 rectangular walls.

You will need to calculate A to get R to get rc. To get A, take the surface area of each element times its absorption coefficient to get the number of sabins for that element, and sum all elements' absorption in sabins to get A, or total absorption in sabins. This can be written as the equation A=(sum)sa. Absorption coefficient charts for common materials can be easily found online, and values should be available for any acoustical treatments from the manufacturer.

So... all that, and critical distance really doesn't matter in a room like this. I bet if you ran the numbers, it would come out to be close to or beyond the walls. Calculations like this, including traditional RT60, especially from the Sabine equation (RT60=.049V/A), are far more useful and reliable for large room acoustics.

By the way, these equations are for American feet. For metric or SI, figures like A and R will be for meters squared instead of feet squared, critical distance will be meters rather than feet, and the Sabine equation becomes T60 (or RT60) = .16V/A, where V is volume in cubic meters and A is metric sabins calculated for meters rather than feet.
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Quote:
Originally Posted by naethoven View Post
Wes, when you say back of the room, you do mean close to the REAL/rigid wall, not the false back wall with 4 ft of hangers behind it, correct? How far away from the back wall?

And what about just angling the glass at the floor to handle the HF ref?
Yes, correct.

I don't believe you can get enough of an angle to do the trick.

--Wes
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Originally Posted by naethoven View Post
Here is my latest. I just left off the treatment for now, just focusing on the shape and placement of things right now. I moved the couch back, readjusted the angles of the front wall and located the 1st ref points to treat for RFZ. I plan to start my glass AFTER these points of treatment, extending from there toward the back wall.

Do I need to be concerned with the 1st reflections reaching the couch (about 14 ms total travel time, not 14 later than direct)? How do I address these?

Can you please teach me about the critical distance where reverberant sound = direct, and what the importance of it is? What do I do with it?

Thank you
I don't think your ray tracings take into account all of the possible angles of incidence.

Yes, you need to take into account first reflections for any listening position where you are trying to get reasonably accurate sound reproduction.

As far as the critical distance is concerned, you're not that worried about reverberant sound once you treat the room adequately for a rear listening position.

By the way, getting a rear listening position to be accurate is pretty esoteric stuff. If this is your first studio design and you're working with a limited budget (neither of which I know for sure to be the case) I would say you should first concentrate on getting dead accurate sound at the main engineer's position. That design problem alone is enough to keep you occupied for quite a while.

--Wes
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This is an incredible read

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Quote:
Originally Posted by jayfrigo View Post
Don't worry about critical distance in a small room like this, especially with the treatments likely to go into a studio control room build. You really don't get much of a reverberant field (or statistical sound field) in such a small, absorptive room. It's effectively direct field anywhere you are likely to put your ears.

If you really want to calculate it, the formula is rc=square root of R/16(pi)D.

The "c" is really a subscript, meaning critical, and r means distance. This is because point sources spread spherically; the source is at the center, and the sound expands like a balloon being blown up. This means that a radius on the sphere is equal to the distance from source to receiver (listener). So r, or radius, always refers to distance.

So, r(sub)c is the critical distance - where the direct field and reverberant field meet, and the direct sound and reverberant sound are equal. Beyond the critical distance from the source, you are in the reverberant field and hear a greater proportion of reverberant sound to direct sound. Closer to the source than the critical distance, you hear more direct than reverberant. The direct field is essentially a bubble around the source. The distance is like a sphere around the point source. It's not like it's a straight line across the floor.

Inside the square root you get R (capital R this time) which is the Room Constant, divided by 16 times pi (3.14 etc.) times D, which is the directivity factor of the source. Optionally you can use "Q" which goes in the numerator instead of the denominator. Q = 4 equates to D = 1/4. The accepted Directivity factor for human speech is 1/2, or in the case of the math, a decimal value of .5 because you can't have a fraction in a fraction. For your source, you would need to know the directivity of your speakers, and if it changes significantly with distance in case the relevant distances make a difference. You also need to consider that you have two speakers radiating rather than a single source.

Next, you'll need to calculate the Room constant. You can do this with the equation R=A(sum)s/(sum)s - A, where A is the total absorption in sabins, and (sum)s, or greek symbol "sigma" s is the sum of the surface areas. This is the total area of all 4 walls plus ceiling and floor, or in your case, sum of each angled surface since it's really more than 4 rectangular walls.

You will need to calculate A to get R to get rc. To get A, take the surface area of each element times its absorption coefficient to get the number of sabins for that element, and sum all elements' absorption in sabins to get A, or total absorption in sabins. This can be written as the equation A=(sum)sa. Absorption coefficient charts for common materials can be easily found online, and values should be available for any acoustical treatments from the manufacturer.

So... all that, and critical distance really doesn't matter in a room like this. I bet if you ran the numbers, it would come out to be close to or beyond the walls. Calculations like this, including traditional RT60, especially from the Sabine equation (RT60=.049V/A), are far more useful and reliable for large room acoustics.

By the way, these equations are for American feet. For metric or SI, figures like A and R will be for meters squared instead of feet squared, critical distance will be meters rather than feet, and the Sabine equation becomes T60 (or RT60) = .16V/A, where V is volume in cubic meters and A is metric sabins calculated for meters rather than feet.
WOW JAY. I REALLY appreciate your details. THAT kind of info makes me grow and feel like I've been to class. THANK YOU! (Wes, likewise!)
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5th June 2009
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Quote:
Originally Posted by Wes Lachot View Post
I don't think your ray tracings take into account all of the possible angles of incidence.
I was really just looking at reflections that are both 1)off the glass and 2)directed at mix pos. (I will go back to check for others I may have missed though)


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Originally Posted by Wes Lachot View Post
If this is your first studio design and you're working with a limited budget (neither of which I know for sure to be the case)
Both are the case
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Nathan,

Okay, that makes sense. I recommend doing a detailed drawing of the room with the glass clearly labeled, and doing the ray tracings from both speakers at all extremes for each wall segment. Then it will be more obvious whether it's working or not, with regards to reflections at the mix position.

-Wes
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8th June 2009
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Here is my latest diagram. I changed a few angles for ergonomic reasons, made the windows more clear, traced rays from each speaker to each side wall to mix pos, and added treatment in order to keep the windows where I need them. I did experiment with angling the glass, and my room is just too small for the geometry to work : (

The absorption for RFZ is in orange, and there will be a cloud on the ceiling. The rays are traced on the floor. The top edge of the "speakers" marks the highest point of the acoustical center of the speaker. The top edge of the "mix position pedestal" marks the height of the ears of the engineer. (I purposely only treated the point of incidence with absorptive treatment, not extending it to cover the point of reflection. I just figure that makes sense.)

Tell me what you think!

Nathan Webb
Attached Thumbnails
Angles of Control Room walls-1-14-166-fix-rfz-mix-pos-2-3d.jpg   Angles of Control Room walls-1-14-166-fix-rfz-mix-pos-2-top.jpg  
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8th June 2009
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Originally Posted by naethoven View Post
Here is my latest diagram. I changed a few angles for ergonomic reasons, made the windows more clear, traced rays from each speaker to each side wall to mix pos, and added treatment in order to keep the windows where I need them. I did experiment with angling the glass, and my room is just too small for the geometry to work : (

The absorption for RFZ is in orange, and there will be a cloud on the ceiling. The rays are traced on the floor. The top edge of the "speakers" marks the highest point of the acoustical center of the speaker. The top edge of the "mix position pedestal" marks the height of the ears of the engineer. (I purposely only treated the point of incidence with absorptive treatment, not extending it to cover the point of reflection. I just figure that makes sense.)

Tell me what you think!

Nathan Webb
Nathan,

That's quite a lot of glass in the front of the room. I'm not sure how you're doing your ray tracings, but I can tell you from having done quite a few of them that you can't create an RFZ with that one skinny piece of fiberglass in the one spot per side. There are more ray paths going on than that. You have to consider that each speaker is an omnidirectional sound source. And you have to create a "zone", not just a central spot, where there are no first reflections. That zone should cover the entire width of the console, not just directly behind the console but also over top of it, where you might lean your head in to make an EQ adjustment, etc.

Have you considered any alternative layouts between the CR and the Studio, so that you can avoid side glass forward of the mix position?

Wes
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Quote:
Originally Posted by Wes Lachot View Post
Nathan,

That's quite a lot of glass in the front of the room. I'm not sure how you're doing your ray tracings, but I can tell you from having done quite a few of them that you can't create an RFZ with that one skinny piece of fiberglass in the one spot per side. There are more ray paths going on than that. You have to consider that each speaker is an omnidirectional sound source. And you have to create a "zone", not just a central spot, where there are no first reflections. That zone should cover the entire width of the console, not just directly behind the console but also over top of it, where you might lean your head in to make an EQ adjustment, etc.

Have you considered any alternative layouts between the CR and the Studio, so that you can avoid side glass forward of the mix position?

Wes
Wes,
I traced rays for the entire console area, and decided to just extend the panels all the way to the front wall. As far as I can tell this should cover any 1st reflection aimed anywhere in the console area. I am finding my rays by: point of reflection = 1/2 distance between line perpendicular to wall from source, and line perpendicular to wall from listener. Is that accurate/does the explanation make sense?

I have tried every layout I could imagine for the last 10 months, and this is the best scenario I could come up with for volume, use of space, line of sight, and needs of bath/iso, etc.

Thanks so much,
Nathan

P.S. I had been considering the omnidirectional nature of the source, but I had not (until this diagram) addressed the "zone" other than my central pos. Also, please ignore that blue rectangle on the floor, I am in a hurry and have no idea why it is there!
Attached Thumbnails
Angles of Control Room walls-1-14-166-fix-rfz-mix-pos-2-extremes.jpg  
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8th June 2009
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If it were me, I'd opt for a hanging panel over the window while mixing, and remove it for tracking. Even if the amount of absorption you have rendered is enough, to me it looks like an after thought sticking up in front of the window... like you hadn't considered it in the original design.

I've also seen designs incorporate a panel on a track that would slide over from behind, but your angled walls may prove that impossible.

Closed circuit video would be another option.

My control room is two stories up from my tracking room. Admittedly, it's mainly a personal use studio, but the few times I've had bands in, they actually said they really liked the lack of visual ties to the engineer, as they felt a bit less self-consious. My guitarist and I have developed a way of working around it, our talk back is run through the practice p.a., and there is always a room mic that is hot regardless of it's being used or not. Not saying I wouldn't take a window if I had the option though
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8th June 2009
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It seems like that side window could be smaller, and not have to go all the way to the front. Even that small change would help.
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Originally Posted by dykstraster@gmai View Post
If it were me, I'd opt for a hanging panel over the window while mixing, and remove it for tracking. Even if the amount of absorption you have rendered is enough, to me it looks like an after thought sticking up in front of the window... like you hadn't considered it in the original design.
I hear you man. I don't like the whole "after thought" look either... I saw a VERY nice studio once that had long, skinny absorbent peices (looked kind of like 1/2 round tube traps) mounted all around the front end of the control room, and even over the window. I have a pro engineer friend who says it was one of his favorite CR to mix in. I'm considering mounting strips like that, it looked really good in that studio. I'll post a new pic when I get back to my computer, I'm not at home right now.

Aside from the issue with the glass, does the rest of the design look solid to you guys? I'm interested to know what issues I would still be fighting once I have a solution to the window issue. Please advise!

Thank you all,
Nathan Webb
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