The Cottage Studio Build

And here are the rest of the foundation photos...

A lot has gotten done in the past few days... we have most of the rough framing done. Still need to frame the roof and upper rear wall. Then we are ready for our rough framing inspection. Here are a few photos as you can see the building is starting to take shape.

Almost all of the sheathing is done! Next will be rough framing inspection from the city inspector.

Little progress has been made lately. It turns out the builders framed the front and rear wall incorrectly. The plans called for "balloon framing" walls on the front and back because of the height of the building, the front and rear walls could act like large sails and destroy the structure. So, we have been waiting for a fix from the structural engineer, since the builder says it would be too expensive for him to tear down both walls and reframe them. We finally received the fix, and hopefully they will be starting that tomorrow. But now that brings up a new question... the fix calls for sistering up new 2x6 studs along side the existing 2x6 studs. I was planning on beefing up between the studs with 2 layers 5/8" drywall and green glue, caulk, etc. but what about where the 2x6's meet? It seems like simply caulking the joint would work? Below are some pictures and diagrams.... Thanks in advance.... Beau

Hey Beau, Easier and cost efficient !!! Add another layer of OSB on the outside. Material price fairly close , labor less than half. Stagger the seams. Trust me it takes forever to cut and install those panels between the 2x6's and caulk them. my 2 cents T

"The new garage will be 19' x 27' with 10' header height and a roof with an 8/12 pitch." See this started out a garage and the garage mentality has not modified the want for an acoustic environment. And you will or hopefully can, forgive me when I ask or give statements that may not seem fit to you as the builder/contractor/owner whichever it is. As you were already told you missed a HUGE opportunity to isolate the slabs, interior from the exterior. But I will take that even a few steps farther. It would not have made any significant change in the structure to pour the footing and lay a poured block foundation. Once that poured block foundation was in place you have the exterior dimensions to pour the interior slab, with no direct contact to the exterior. But even beyond that not only was this "attempt" not approached, the slab is so tied together with rebar that there is no way you will ever get the exterior side of the structure out of the interior side, why was that done? And don't give me that California stuff like rebar is going to modify the ability of concrete to withstand an earthquake. If that were true the whole structure would be concrete and rebar. I will submit a few more things before I move on to the reason my knees jerked, if you will :) That roof is completely un-braced. You are not only not ready for an inspection you are fooling yourself if you think that it will pass. Granted the process may be different due to regional administration tactics, but the plumbing/electrical/HVAC gets signed off before a final framing inspection. Why you ask? Because of the loads placed on the structure. Again, you guys may have a three step framing inspection, which just goes to show why Californians and the delegates that choose or were chosen to represent her have California in the situation they are currently in. Let me preach on...

beau wrote:

... The plans called for "balloon framing" walls on the front and back because of the height of the building, the front and rear walls could act like large sails and destroy the structure.

Balloon framing has long since gone out of style and is outlawed. Typical platform or western framing is the standard. No big secret why since you effectively create a chimney that air/fire can pass through unrestricted into the upper areas of the structure allowing that fire to spread. To add more mass with a "sistered" stud only adds to the potential for this weather beaten wall to shift, other than that it will do little. I refer you back to the roof bracing that has not been seen as of yet but will also submit a simple solution. If you guys would have actually been building an acoustic environment instead of a garage (and we have not even addressed the reduced TL that the roll up door is going to produce) your, for lack of a better term, architect would have suggested a vaulted ceiling that is supported with poles embedded in the Earth that would have supported the roof and added the shear ability to the structure. That said...it is not uncommon for a gable ended roof to be braced and to have the ability to support said roof against inclement weather. I submit to you I live in Hurricane alley and have worked on gable houses for decades with no loss. Saving a falling tree or twelve:)

Thanks! I had a feeling that was the answer.... Right now, it's half inch plywood as the existing sheathing. Would it be best to do another half inch layer? or 3/4"? Osb or Plywood? Beau

Hi xSpace, I'll try to answer best I can..

xSpace wrote:

"The new garage will be 19' x 27' with 10' header height and a roof with an 8/12 pitch." See this started out a garage and the garage mentality has not modified the want for an acoustic environment. And you will or hopefully can, forgive me when I ask or give statements that may not seem fit to you as the builder/contractor/owner whichever it is.

Owner

xSpace wrote:

As you were already told you missed a HUGE opportunity to isolate the slabs, interior from the exterior. But I will take that even a few steps farther. It would not have made any significant change in the structure to pour the footing and lay a poured block foundation. Once that poured block foundation was in place you have the exterior dimensions to pour the interior slab, with no direct contact to the exterior. But even beyond that not only was this "attempt" not approached, the slab is so tied together with rebar that there is no way you will ever get the exterior side of the structure out of the interior side, why was that done? And don't give me that California stuff like rebar is going to modify the ability of concrete to withstand an earthquake. If that were true the whole structure would be concrete and rebar.

After almost a year of trying to get a permit for a simple garage, this design got the go ahead, so I had to roll with it.

xSpace wrote:

I will submit a few more things before I move on to the reason my knees jerked, if you will :) That roof is completely un-braced. You are not only not ready for an inspection you are fooling yourself if you think that it will pass. Granted the process may be different due to regional administration tactics, but the plumbing/electrical/HVAC gets signed off before a final framing inspection.

yes, rough framing inspection comes first. I am not sure what bracing is, but the way the roof is built is the way the structural engineer specified it to be. Let me know if there is any details about the roof I could show you to help clarify anything.

xSpace wrote:

Why you ask? Because of the loads placed on the structure. Again, you guys may have a three step framing inspection, which just goes to show why Californians and the delegates that choose or were chosen to represent her have California in the situation they are currently in.

I totally agree... California is in sad shape, and I'm not sure the people at the permit department can tie their own shoes...

xSpace wrote:

Let me preach on...

beau wrote:

... The plans called for "balloon framing" walls on the front and back because of the height of the building, the front and rear walls could act like large sails and destroy the structure.

Balloon framing has long since gone out of style and is outlawed. Typical platform or western framing is the standard. No big secret why since you effectively create a chimney that air/fire can pass through unrestricted into the upper areas of the structure allowing that fire to spread.

Ya, I read the same thing about balloon framing. It's obviously not outlawed here, but even my contractor was surprised about the balloon framing, hence the misunderstanding.

xSpace wrote:

To add more mass with a "sistered" stud only adds to the potential for this weather beaten wall to shift, other than that it will do little. I refer you back to the roof bracing that has not been seen as of yet but will also submit a simple solution. If you guys would have actually been building an acoustic environment instead of a garage (and we have not even addressed the reduced TL that the roll up door is going to produce) your, for lack of a better term, architect would have suggested a vaulted ceiling that is supported with poles embedded in the Earth that would have supported the roof and added the shear ability to the structure.

The vaulted ceiling was my original plan. I was told that with all of the beams it would take to support it, it would be very costly. However, at this point, I'm starting to feel like this plan is rivaling the original quote.

xSpace wrote:

That said...it is not uncommon for a gable ended roof to be braced and to have the ability to support said roof against inclement weather. I submit to you I live in Hurricane alley and have worked on gable houses for decades with no loss. Saving a falling tree or twelve:)

Thanks xSpace, let me know if there is any other information you need to keep helping. Even though I may not be able to implement some of the advice, I still very much appreciate it. I'm at the point where I just need to get the garage done, so I can start the studio build and get back to work. Thanks again, Beau

We passed our framing, sheeting and roofing inspection, as well as our "green inspection." So now we have the green light to finish the rest of the garage! :) Regarding the extra layer of plywood / osb on the outside of the garage, it turns out I'll be substituting the extra layer of plywood / osb for a layer of 5/8" exterior drywall that must be placed under the hardy plank siding. Apparently, the hardy plank siding is not 1 hour fire rated, so in order to meet the Los Angeles 1 hour fire rating, the construction from the outside in will look like this... hardy plank siding, 5/8" exterior fire rated drywall, 1/2" plywood sheeting, 2"x6" stud with insulation, 5/8" fire rated drywall. The code says that only the walls 3' from the property line must be constructed like this, but my plan is to continue the external drywall all the way around the outside of the garage, beefing up the outer layer. Unfortunately, the internal layer of drywall must be installed to pass inspection, but that will be coming down once final inspection is passed. My question now, is about caulking. As I understand it, the intention is to caulk all seams and joints, right? so basically any place where 2 pieces of material join together? I have a few cases of green glue acoustical caulk, would it be best to use this caulk for all caulking duties? or are there better caulks for different duties? Thanks again, Beau

Ok... quite a few months have gone by, and here is where I am at. Garage Construction... Complete. Inspections ......Complete. Certificate of Occupancy received. Studio Construction. Control room framed, with 2 layers 5/8" drywall caulked with green glue acoustic sealant at every seam with the exception the wall on the side of the iso booth. (Currently this layer has only one layer of drywall, but will have 2 or possibly 3 depending on the answers I get on the next post.) Here are some photos.... and in the next post, I will post the questions I have regarding isolation concepts for the iso booth.

So my question is regarding the isolation between the control room and iso booth to the outside / airlock. Is this proposed green wall necessary? Assuming the iso booth wall would be 3 layers 5/8" drywall on the inside, 2x4 studs, with ultratouch insulation between studs, this would give me a 2 leaf system all the way around... so my question is this green wall extending from floor to ceiling be helpful with adding isolation from sounds coming through the entry door? Thanks in advance, Beau

Yes, it is necessary. If you don't have that, the your entry door opens directly into your air gap... - Stuart -

Thank you so much Stuart! Yesterday I finished the 2nd and 3rd layer of drywall on the control room wall that borders the iso booth. I also finished framing the iso booth. I will post pictures shortly. Beau

Hey all, So It's been quite a while, and I've made quite a bit of progress. Completed construction on the control room and iso booth. Tracked a few records in there and now starting construction on the upstairs lounge and bathroom. I'm going to take some measurements and post them as soon as I get a a free minute. I've been struggling with getting rew to work correctly. The impulse response keeps coming up unusable. I'm going to dive in and review the tutorials. My main issue I am noticing is an issue of low frequencies reflecting off of the rear wall causing a null at the mix position. I came to this theory because when I roll in my chair towards the rear of the room, the null frequency rises. At my mix position it is around 114hz, and as I roll my chair back to the rear of the room, it goes up to around 200. So it's really just within that range. Moving left to right and standing or sitting has no effect. Right now, the entire rear wall is covered with 14 inches of pink fluffy insulation from floor to ceiling, wall to wall. All walls are inside out walls with 3.5" ultratouch between studs, faced with fabric. Speakers are flush mounted. Below is a picture of the floor plan and dimensions. The ceiling (shell) has a height of 9.5' I'm wondering if some of the Hidley / Newell wave guide hangers instead of the existing insulation would help with the low frequency reflections coming back off the rear wall. Possibly a low frequency diffuser? Something to guide the low frequencies away from my mix position.

Ok, so here are some photos of the control room in it's current state. It's messy and still needs some finishing work cosmetically. But this will hopefully give you a clearer picture of the room. As all home studios are, it is a work in progress, but I had to get working on projects I was committed to. I would like to add some diffusion to liven up the room a bit, being that it is completely absorbent with the exception of the flush mounted wall and the floor. Treatment so far. The blue area above the mix position is filled completely with pink fluffy insulation. sloping from 6" -24" The center section between the flush mount walls is filled with 20" of pink fluffy insulation. The side walls are filled with 3.5" ultratouch Rear wall is 14" pink fluffy from floor to ceiling, wall to wall The angled grey sections of the ceiling are .5" mdf panels filled with ultratouch and pink fluffy. The grey flat section above the couch is 14" of pink fluffy. Again, My question is regarding the low frequency reflections coming from the rear wall. From the research I have done so far, I'm thinking the newell rear wall absorber and hangers might be an option, But I'm having trouble finding any data on how much space is needed for them, as well as exactly what materials would provide absorption / diffusion of 100-200hz. I have read that it is questionable whether or not hangers work better than super chunk / wall to floor pink insulation. Thanks in advance. Beau

I've been struggling with getting rew to work correctly. The impulse response keeps coming up unusable. I'm going to dive in and review the tutorials.

What type of computer are you using? Mac or PC? There are issues with Java on some versions of the Mac OS: it was not implemented correctly for handling sound streaming, so you need to jump through hoops to make it work right. I've been through that with a few builds lately, and the problem can present more or less the way you describe. So if you are on Mac, then let me know and I'll PM you the work-around. But if you are on a Windows PC there should be no problems with Java, so it would be most likely be a setup or calibration issue.

My main issue I am noticing is an issue of low frequencies reflecting off of the rear wall causing a null at the mix position. I came to this theory because when I roll in my chair towards the rear of the room, the null frequency rises. At my mix position it is around 114hz, and as I roll my chair back to the rear of the room, it goes up to around 200.

Then it isn't really one issue, but rather several: it's not the frequency of the null "changes", but rather that you are moving from one null to another, with each one being at a different frequency. What are the final dimensions of the hard boundaries of the room inner-leaf, excluding all treatment? It looks like 17'6-1/2" long by 16' 8" wide: correct? But what's the height? And where is your head located in that room? (how many feet/inches from the rear hard boundary, and above the floor?

I'm wondering if some of the Hidley / Newell wave guide hangers instead of the existing insulation would help with the low frequency reflections coming back off the rear wall. Possibly a low frequency diffuser?

I though the original plan WAS hangers???? How did that get changed to very thick insulation? Also, what type of insulation is it? (fiberglass/rockwool, density, etc.). Any air gap behind? I would suggest maybe trying very large poly-cylindrical diffusers on the rear wall, or maybe large pyramid diffusers. But first I would get REW working and see what the actual problems really are.

Something to guide the low frequencies away from my mix position.

If it is a modal problem, then you can't "guide it away" anyplace. You can either damp it, or try to break it up. And damping doesn't seem to be working...

The blue area above the mix position is filled completely with pink fluffy insulation. sloping from 6" -24" The center section between the flush mount walls is filled with 20" of pink fluffy insulation. The side walls are filled with 3.5" ultratouch Rear wall is 14" pink fluffy from floor to ceiling, wall to wall The angled grey sections of the ceiling are .5" mdf panels filled with ultratouch and pink fluffy. The grey flat section above the couch is 14" of pink fluffy.

To me, it sounds like you might be over-doing the absorption somewhat. That room must be sounding pretty dead right now. You probably need to liven things up a bit in places. But once again, REW will tell....

But I'm having trouble finding any data on how much space is needed for them, as well as exactly what materials would provide absorption / diffusion of 100-200hz. I have read that it is questionable whether or not hangers work better than super chunk / wall to floor pink insulation.

Hangers done right (the John Sayers way) can be very effective for low frequencies. Materials are 1/2" Homasote for the core, then at least an inch (better 2" if you have the space) of insulation on each side, hung from wires to swing freely, and spaced at the 1/2, 1/4, 1/8, 1/16, 1/32 wave points across the rear wall. - Stuart -

Thank you Stuart! I am running a macbook for measurements. I was able to get rew to work using windows on bootcamp. Here is a link to impulse responses taken from 9, 10, 11 and 12 feet from the rear wall. All measurements are taken 4' from the floor. (I couldn't upload them to the forum) http://www.beauburchell.com//Impulse%20 ... -11-13.zip Room Dimensions. Yes, the room is roughly 16'8" wide, 17'6" long, 9'5" tall. My listening position is 4' from the floor, roughly 10'-12' from the rear hard boundary. The rear wall is as follows. from outside in. 2 sheets 5/8" drywall, 2x4 studs, 3.5" ultra touch insulation between studs, pink r30 fiberglass insulation, stud frame with ultratouch between the studs, fabric. No air gap. Yes, It is quite dead in here, and I would like to liven it up a bit, but my main concern is this low frequency null. :( I don't know why I didn't do hangers. I want to say it is because the internet told me there was not enough test data on them, and that the superchunk style wall was tested and just as effective. I also couldn't find any information on how to tune them, or how much space was needed, or what sizes they should be. That being said, I think I could give up another 9" of floor space to make the rear wall absorption / trap more effective. I could also give up some corner space, although the visible corners at this point are not the actual hard corners. Hopefully the IR files will will work. Thanks again, Beau

here are 3 waterfall graphs from 9, 10 and 11 feet from the rear wall. It looks like the best place to be would be 9 feet from the rear of the room because of the nasty null that 11ft has at 105hz. 10 gets a little better at 117hz. but the smallest null is at 125hz in the 9 feet position. I would like to think by absorbing from 100-150 hz, these nulls should decrease. Does that sound reasonable? or am I way off in that thinking? B

Glad to see that you got REW working! That's great. Now it will be easier to actually understand what you are dealing with. Actually, you are sort of going about things backwards here: focusing on only one single aspect of acoustics, while ignoring all the others, which are equally important, or maybe even more important! :) For example, placing your head at 9 feet from the rear wall might well be good from the modal situation, but it also places you too close to the rear wall, where early reflections will be arriving in less than the Haas time, and therefore coloring the perceived sound, as well as moving it spatially. Also, that places you too far away from the speakers, messing up your geometry (the famous "triangle"), and possibly placing you beyond the critical distance (in the acoustic far field, when you should be in the acoustic near field), as well as moving your first reflection points further back in the room, and very likely also changing your perception of reflections (from the impulse response graphs). Among other things.... What you are trying to do is to treat the room first, then trying to find a place where it doesn't sound too bad, to set up your listening position. In reality, you should do it the other way around: set up your listening position in the best position first, then treat the room accordingly. Also, from those graphs it seems that you have the modal issues fairly well under control, (although it would be good to see how things look at lower levels, say down around 50 dB, or even 40), so that isn't even your problem! Your modes seem to be well damped, and hardly evident at all. So very likely what you are seeing is something else, such as some form of SBIR. What speakers are you using? (make and model). - Stuart -

Thanks Stuart! I do plan to focus on the whole spectrum, and I will be here asking questions when I get to it. :) Listening position, I will mark my listening position and report back later this evening. I am going to re-measure tonight because I think my marker for measurements may have been off a whole foot, meaning 10ft from rear wall is actually 11ft from rear wall... etc... So I'm going to re-measure to be sure. That being said, I will take some measurements at 40 and 50db tonight. Is there any other measurements or methods you would like me to use or try? Beau

I do plan to focus on the whole spectrum,

It's not just the spectrum that I'm concerned about: frequency is only a part of what REW measures. The other major part is time-domain, and the other way of looking at both of those is with the IR analysis (Impulse Response). They all reveal different aspects of what the room is doing, so they are all important. And it's better to look at the big picture every now and then, as well as focusing on the individual parts in between, since everything is related to everything else... :)

That being said, I will take some measurements at 40 and 50db tonight.

All of your measurements should be done at 83 dB for each speaker, meaning about 86 dB when both are on. That's where you should have calibrated your system. Did you follow the full calibration instructions for REW? If not, I can send you the method I use for calibrating, which is a bit more complete than what they describe.

Is there any other measurements or methods you would like me to use or try?

Just make sure you are measuring all your dimensions and distances from the hard boundary of the room NOT the face of the treatment. So you should measure all the way to the drywall (or whatever it is) in all directions. Your ceiling is rather intriguing! It seems to slope upwards nicely, but then drops back down in a series of "kinks", almost like an old Hidley compression ceiling... but at the wrong end of the room. What's up there, making those strange shapes? Structural beams? HVAC ducts? Something else? Also, please post the make and model of your speakers, so I can look them up on-line and find out how they should be behaving, then compare that against how they are actually behaving. Also, please do one set of REW tests with the mic in the current listening position (which should be about 12" in front of the apex of the speaker triangle), with JUST the left speaker turned on, another with JUST the right speaker turned on, and one last one with BOTH speakers together. Post the resulting MDAT file some place like Dropbox, then post the link here so we can download it and analyze it more completely. Also post your sound card calibration file, and your mic calibration file (if you have one). What mic are you using for the measurements? - Stuart -

All of your measurements should be done at 83 dB for each speaker, meaning about 86 dB when both are on. That's where you should have calibrated your system. Did you follow the full calibration instructions for REW? If not, I can send you the method I use for calibrating, which is a bit more complete than what they describe.

That would be great! I am using a first generation m-audio fast track for the measurement, but because it does not have phantom power, I am using a preamp in front of it to provide phantom power to the test mic.

Just make sure you are measuring all your dimensions and distances from the hard boundary of the room NOT the face of the treatment. So you should measure all the way to the drywall (or whatever it is) in all directions.

Yes, That is the method I have been following.... with the exception of a possible screw up on my last measurement.. ;)

Also, please post the make and model of your speakers, so I can look them up on-line and find out how they should be behaving, then compare that against how they are actually behaving.

Monitors are Tannoy DMT 215. Right now they are powered by a single stereo amp, but once the room is treated properly, then I plan to experiment with tri-amping them using a deqx for crossover and eq. you can visit http://www.deqx.com and look at the hdp3. That is the unit I will be using.

Your ceiling is rather intriguing! It seems to slope upwards nicely, but then drops back down in a series of "kinks", almost like an old Hidley compression ceiling... but at the wrong end of the room. What's up there, making those strange shapes? Structural beams? HVAC ducts? Something else?

The front ceiling is 3.5" ultratouch insulation between the 2x4 framing, then the entire cavity is filled with r19 fiberglass insulation. The rear of the ceiling is as follows. The 2 angled saw tooth looking sections are half inch mdf boards angled downward with a 1' opening facing the rear of the room. They are loosely filled with 3.5" ultratouch insulation. My acoustics guru friend said that it would serve 2 purposes. 1. breaking up the floor to ceiling modes in that area, and 2. serving as a low mid frequency absorption. I think it functions as a dampened membrane? I can dig up some pictures of the construction if it helps. The original plan was to use those panels to mount these diffusers. http://www.zainea.com/ESR%20ACOUSTICS%2 ... Theory.pdf but I'm looking into other diffusion elements that will hopefully be more cost effective, and possibly more visually appealing.

Also, please do one set of REW tests with the mic in the current listening position (which should be about 12" in front of the apex of the speaker triangle), with JUST the left speaker turned on, another with JUST the right speaker turned on, and one last one with BOTH speakers together. Post the resulting MDAT file some place like Dropbox, then post the link here so we can download it and analyze it more completely. Also post your sound card calibration file, and your mic calibration file (if you have one). What mic are you using for the measurements?

Ok, I will do that. I do not have a mic calibration file. Just using the cheap behringer test mic. B

Sorry for the delay on measurements. I am in Korea for the weekend, and I was not able to get the measurements done before I left. But it has given me some more time to think about the rear wall treatment. Assuming that my problem is being caused by low frequency reflexions from the rear wall coming back to the listening position. Absorption of those frequencies at the rear wall would be my solution, right? If that is the case, what kind of absorption would you recommend for this type of problem. I am prepared to sacrifice 2' of depth from the rear wall in the center of the room where the couch lives, and possibly 3' on the sides of the couch if it would show considerable gains. I just finished reading Newell's studio design book, and from the information given there, combined with the hangers section on the forum, I'm not sure what kind of absorption would be most efficient at those frequencies. It seems like in order for the hangers to be effective, they need to be combined with some sort of limp membrane absorber on the rear wall? And for hangers, would this sound board material be appropriate for my application? http://www.homedepot.com/p/440-1-2-in-x ... g7E4hbOL8s and is there any advantage to using a certain type of insulation vs. another type of insulation for the hangers? If I go the route of just fiberglass insulation / superchunk absorber along the whole wall, then the most effective method would be to have an air gap between the wall and the superchunk? if so, how is the air gap calculated? and what calculations would I need to determine how thick the absorber needs to be in order to absorb efficiently at 100hz? B

Ok. Here is the MDAT File... http://www.beauburchell.com//impulse%20 ... 22-13.mdat I included 9 and 10 ft measurements.. at this point, 10ft feels better overall when listening to music, but 9 ft is actually the proper mix position... At this point in the game, I am willing to redo my front flush mount wall in order to put my listening position in the best place for the room... probably something I should have done before.. :( Hopefully with the data here in the measurements, we will be able to determine if it is necessary, or if it will even be of help? Here is a link to the impulse responses of all 3 positions. http://www.beauburchell.com//impulse%20 ... ponses.zip Here is a photo of how the front wall looks at this point. possibly turning the speakers on their sides so that the drivers are stacked on top of each other, this would also bring the listening position significantly closer to the front wall. or maybe just bringing them in tighter...?

Here is the MDAT File...

Assuming you did the calibration correctly, then the tests were done at a level that is way too low. The graphs are showing an average level of around 65 dB: It should be about a hundred times louder: 85 dB. At such a low level, there's not enough dynamic range left for REW to be able to give accurate results. So I'd suggest repeating the calibration process for setting the SPL level (using your own hand-held meter), then do the tests again with levels of around 80 dB for the individual speakers, which should give you around 86 dB for both speakers, as seen on both the REW meter and also your own hand-held meter ("C" weighting, Slow response").

possibly turning the speakers on their sides

I'm trying to download the manual for those things, to find out how they are supposed to behave, but all I'm getting is blank pages!. But they do seem to be somewhat large for that room.

so that the drivers are stacked on top of each other,

Does the manufacturer mention that it is possible to do that? The manual should tell you. Not all speakers can be turned sideways, and indeed even the ones that can be, seldom should be. Your NS-10s, for example, are lying on their sides, which is a common error with that type of speaker, especially with a console that is reasonably wide, such as yours. Even small head movements totally distort the perception of the sound field. The NS-10s should be standing up vertically, as they were designed to do. It might be possible to turn those Tannoys sideways, but I would check with the manufacturer to find out for sure.

this would also bring the listening position significantly closer to the front wall.

Not necessarily, and with the design of those speakers, probably not. Where is the acoustic axis of those things? How are those speakers aimed? Where is the intersection of the axes, in relation to your ears? Is that diagram you posted of the studio layout back on August 10, accurate and correct? If so, please add the speaker axes to that, and re-post it. Or better still, post the actual SketchUp file, with the axes added. I'm suspecting that the 116 Hz dip is probably modal. IF those dimensions you gave are correct, then this is the area around that frequency: 111.1 hz 3.9% 10'2", 5'1", 2'7" (2,2,1 Oblique) 113.7 hz 2.2% 9'11", 4'12", 2'6" (3,0,1 Tangential) 118.0 hz 3.6% 9'7", 4'9", 2'5" (3,2,0 Tangential) 118.1 hz 0% 9'7", 4'9", 2'5" (0,3,1 Tangential) 118.7 hz 0.5% 9'6", 4'9", 2'5" (3,1,1 Oblique) 120.0 hz 1% 9'5", 4'8", 2'4" (0,0,2 Axial) I'm guessing that it's actually the 0,0,2 axial mode you are seeing there, which is related to the vertical axis of the room (height), so modifying the rear wall is not going to help much. All of those (except 118.0) involved the ceiling, and all of them as the first or second harmonic. I suspect the ceiling.

At my mix position it is around 114hz, and as I roll my chair back to the rear of the room, it goes up to around 200.

That isn't evident on the graphs at all. 200 Hz doesn't change at all for any of the readings for the 9 and 10 foot positions as measured by REW. I loaded the impulse response files into REW as well, but they are highly suspect: they claim to have been taken at a level of over 150 dB! :shock: Somehow, I doubt that is true!!! I had to adjust them down by 84 dB to get them to the same level as what was measured by REW. They also suddenly crash down to nothing at 2 kHz, which is also highly unlikely. How were those measured? But even though they are suspect, even they do not show any changes at 200 Hz. In fact, 200 Hz is about the most stable and consistent point across all of the graphs! So I don't understand why you have the impression that 200 Hz has a null at any of those locations. Maybe you did not have the mic at the same height as your ears when you measured?

The angled grey sections of the ceiling are .5" mdf panels filled with ultratouch and pink fluffy.

Why? What is the purpose of that? 1/2" wood over a 1" - 4" gap will, indeed, give you major absorption in the range of about 150 Hz to 80 Hz, give or take a bit. That's exactly in the range where you are seeing a major null... Hmmm....

said that it would serve 2 purposes. 1. breaking up the floor to ceiling modes in that area,

It's way too small for that, and in the wrong location too. Modes are at low frequencies, meaning large wavelengths. Waves pretty much ignore objects that are significantly smaller than their own wavelength. At 116 Hz the wavelength is 9.7 feet long, yet that device seems to be only a few inches across: hence, it is doing nothing to the modes. Modes are big problems: they need big solutions.

2. serving as a low mid frequency absorption. I think it functions as a dampened membrane?

Yup. It sure is doing that, apparently! And is probably tuned rather tightly, perhaps to the problem frequency you are seeing.

I can dig up some pictures of the construction if it helps.

That would be great, yes! ANd if you have photos of how the rest of the room was built too, that would also help. Especially the soffits.

The original plan was to use those panels to mount these diffusers.

It's not clear at all what theory those are intended to operate on, and there's no useful test data on the web site, so I would DEFINITELY skip those! Whenever a manufacturer of acoustic devices does not publish test data from a reputable independent acoustic laboratory, one has to wonder why.... The question comes to mind: What are they afraid of? If they were confident in their products, then they should have no problems in getting them tested. The fact that they don't, leads one to wonder.... Don't get me wrong! I have no doubt that those things do diffuse: But then again, so does ANY piece of randomly warped material. The question is not "Do they work", but rather "How do they work?". If there is no theory, no peer-reviewed paper, and no independent test results, then I would just walk away from such a product.

but I'm looking into other diffusion elements that will hopefully be more cost effective, and possibly more visually appealing.

:lol: 8) :!: But be careful about tuned diffusers in that room: it isn't big enough for most types of diffuser, especially ones based on number sequences.

Assuming that my problem is being caused by low frequency reflexions from the rear wall coming back to the listening position.

I am not at all convinced that your problem at 116 Hz is related to the rear wall. I suspect the ceiling, and most of all I suspect those wooden angled thingies...

it seems like in order for the hangers to be effective, they need to be combined with some sort of limp membrane absorber on the rear wall?

Not really. Hangers work down to fairly low frequencies, and they do not need membrane absorbers in order to work. They work fine all by themselves. A membrane absorber may help, by providing additional absorption at a specific frequency, but it won't help the hangers do their job.

And for hangers, would this sound board material be appropriate for my application?

No. Way too heavy. What you need is something called "homasote". It is a very light weight, low density fiber board product, of the type used to make bulletin boards for use with push-pins (thumb tacks). It is soft and a bit flaky. - Stuart -