Trying to understand sealed cavity vs. not sealed...

Situation: Backyard shed for composition, etc... Exterior dimensions were 8'x12'. Inner dimensions are just shy of 7'4"x11'4" and the ceiling is around 94" without the floor installed. Door is centered on 12' wall. I am in the process of designing the acoustic treatments. I am planning on building 2x2 framing on the inside of the walls (inside out construction?) in order to support the insulation and then covering it with fabric. Basically the whole thing will be covered. Monitors will be on stands. Please let me know if I'm leaving any pertinent information out. Recently, I had asked if it were ok to straddle the corners with acoustic insulation, if I didn't have enough to make proper superchunks. Actually I have enough to make superchunks but only for two corners and was hoping to make what I had stretch a little. Now on to the first question: When fitting the back wall with insulation, I have three different ideas for the framing I am wondering if it is necessary or better to have each section sealed from eachother, or if not, or other fresh ideas I haven't thought of yet. I'm sure you will be able to tell the layout just shows the back wall and the proposed bottom plate, except that the three cavity version has a couple vertical separating members.

Unless you have written a book on acoustics that is used by a global community, there are many "or other fresh ideas I haven't thought of yet." Sorry. You move to fast and ask too many question that you should have already answered before you started this build. Brien

Thank you! Very cool. That was very informative. I think I understand now what I should do. I am sorry that the one question I just asked was too many. I do move very fast. Being constrained by the universe' order of time is something I've always struggled with. The build is not the issue. No problems with build at all. I am working with what I have, and isolation has not been or will not be an issue. The build is what it is. I now have to move my gear out of my home because due to the financial situation of my region, I have more people moving into my home. I am working with what I have and time is not on my side. Let me restate that I am planning acoustic treatment for a room already existing. What I am trying to understand is the effects of sealing off three regions of the back wall that have differing depths. I have read on this board and elsewhere that it is important to seal the area to the sides and back of a cavity of X depth that is faced with insulation. Now... If that cavity encompasses the entire back wall, is it beneficial to also separate the wall into smaller areas?

I am planning on building 2x2 framing on the inside of the walls (inside out construction?)

It can't be both! If it is 2x2 framing attached to the existing wall, then it isn't inside out construction. It is just "2x2 framing attached to the wall". In order to use inside-out construction, you would have had to build your inner leaf as inside construction, but it sounds like your inner leaf is already finished, so its too late to do that now. Either that, or you are not planning to have an inner leaf at all, and are just going to attach treatment to the outer leaf? Your description doesn't make ti clear at all what you have done, and what you plan to do...

Exterior dimensions were 8'x12'. Inner dimensions are just shy of 7'4"x11'4" ...

OK, then I guess I'm not understanding at all. You are talking about using 2x2 framing, yet 4 inches disappeared on each side of the room. Where did the other 2 inches go? Are you saying that you did in fact build an inner leaf, which is not inside out, but in fact the entire inner leaf only takes up 4 inches? That means your air gap is only a bit more than 2 1/2 inches! What kind of resonant frequency is that going to give you, for your MSM? It sounds like it is going to be rather high to me!

I am in the process of designing the acoustic treatments. I am planning on building 2x2 framing on the inside of the walls (inside out construction?) in order to support the insulation and then covering it with fabric. Basically the whole thing will be covered.

If I understand that correctly, you are planning to cover the entire room interior with 2 inches of insulation? That doesn't sound like a good idea to me. You'll end up with a rather dull, "cavey" sounding room. Why did you chose to go that path, and not use a more usual approach to room treatment?

Monitors will be on stands.

OK, so no soffits, but WHERE are you going to place the monitors? They do not appear in your diagrams, and the room does not seem big enough to be able to place them at decent distances from the walls and still get good speaker / mix position geometry.

When fitting the back wall with insulation, I have three different ideas for the framing I am wondering if it is necessary or better to have each section sealed from eachother, or if not, or other fresh ideas I haven't thought of yet.

That all depends on what you are trying to do! f you could be more explicit about the purpose of each section, that would help. If you are just planning what you originally said, which seems to be to cover all the walls with 2" of insulation and diagonals across the corners, then building separate sealed cavities seems pointless. On the other hand, if you are planning to build some kind of tuned device, such as slot resonators, then sealing is paramount! If you could explain how you have designed the treatment, and what purpose each section is designed to fulfill, then it would be easier to help you.

I'm sure you will be able to tell the layout just shows the back wall and the proposed bottom plate,

Bottom plate for WHAT??? I thought you already BUILT the inner leaf? This is really confusing. An accurate and complete SketchUp model of your entire design would help, as would photos of what you have already done and what you still plan to do. - Stuart -

Thank you. I'm sorry I have not been more explicit. Yes, the inner wall has already been completed. Electrical done; standard Insulation, 5/8 drywall hung, caulked, mudded. No floor. Ok, looking back at the drawings, I understand what you are saying about inside out construction. It is not. The walls are pretty standard construction, except for a ceiling about 1.5" lower. I am kind of looking at these plans for inspiration: http://johnlsayers.com/Stuff/Small_Studio.skp The way that there is another framing to support the insulation and fabric cover interior to the walls is I'm talking about. Not the inside out construction between the rooms. Now I see the difference. Yes, I was planning on covering the entire room with 2" insulation. From what I understand, in a room this small there is no benefit from reflections. I will definitely complete a full sketchup of both what I have and what I am proposing. Once again, thank you Stuart for your time and consideration.

I think, based on Stuarts help to you which clarifies my first post, you owe me an apology for your insincere comment on how I did not help you. I am more than willing to help if you are more than willing to slow down AND be more descriptive. Up to this point you are guessing that we know what you are doing...and you are wrong. Then again, not everyone wants the help that I can give. Good luck, Brien

Sarcasm breeds sarcasm. I do not think your post helped me. If there were points which could be better described or completely rewritten from the beginning, I think I would have responded better for a simple "we need more detail/description" Actually, throughout this site, I have found most of what you say, Brien, to be of great benefit. You are one of the posters here that I respect most, as far as what you have to contribute. I think I would have responded the same regardless of who you were. This isn't about personalities. I do however apologize, due to the time constraints I am under, for becoming more frustrated generally. I will have drawings in less than a day.

I have to add, I am really appreciative that a place like this exists and that there is so much time, care and consideration given to DIYers like myself from so many pros that could be doing other things, I'm sure. This is a great environment for science, learning and contemplation of design implementation. I did not mean to come off as ungrateful to the forum whatsoever. Thanks to EVERYONE out there.

Yes, the inner wall has already been completed. Electrical done; standard Insulation, 5/8 drywall hung, caulked, mudded. No floor.

OK, so just to clarify, your inner leaf is built as a 2x2 stud frame, decoupled form the outer leaf, with one single layer of 5/8 drywall on only ONE side of that frame (the side that faces the room), and insulation filling the cavity where the studs are? Is that correct? How deep is the air gap, and what is the outer leaf made of?

The walls are pretty standard construction, except for a ceiling about 1.5" lower.

So does the new inner-leaf ceiling rest on the new inner-leaf walls? Or is it hung form the existing ceiling, maybe with clips and hat channel, or RC, or something like that? I'm just trying to picture what you have.

I am kind of looking at these plans for inspiration: http://johnlsayers.com/Stuff/Small_Studio.skp The way that there is another framing to support the insulation and fabric cover interior to the walls is I'm talking about.

Well, yes, but that's not the same as what you are doing! John designed the CR-LR dividing wall inside out, and most of it is a slot resonator, which you do not have. Then he has soffit-mounted speakers at the front, but you are not doing soffits either: Then in the rear he has bass traps across the corners, which you are doing, but John did those on 34" 2x4 frames with 4" insulation, not 2x2 frames with 2" insulation, which is what you want to use. So it is "similar", but not the same. The acoustic properties are vastly different.

Yes, I was planning on covering the entire room with 2" insulation. From what I understand, in a room this small there is no benefit from reflections.

Actually, there IS a benefit from reflections: It keeps the room live! You don't want a dead room, that's for sure. Dead rooms sound... well ... ummm... they soud "dead"! Not pleasant. However you don't have enough thickness in your plan to make it truly dead (only 2") and you also don't have anything in there to keep it live, so it will be just dull, "honky". You'll be killing frequencies selectively: 2" of insulation up against the wall will be really good at killing off the highs, above about 1,700 Hz., not so good with the mids, and really lousy with the lows. So you'll be taking mostly high-frequency energy out of the room, but doing nothing much to mids and zilch to the lows, therefore leaving it sounding muddy, dull, like a cave lined with carpet, or a steel garbage can with a pillow in the bottom. In other words, it will not be pleasant. That's why John has plenty of reflective surfaces in his room design: to keep some of the highs in the room, not kill them. He has hard-surfaced slot resoantors, large glass doors, a large rear door, and the soffits. All of those are highly reflective and in total they cover a large percentage of the surface area. I'm sure that John also carefully figured that out to get the proper balance between highs and lows, keeping it just right: not removing too much of any specific frequency band, and also not leaving too much in. He also has much thicker insulation than what you are planning: All of the insulation in his design that you referenced is 4", so it works down to at least 850 Hz., but it is also spaced away from the walls, and variable angles, so it works down to much, much lower frequencies, and is broadband. Yours is thin and up flat against the walls. Very, very different. It's not just a simple issue of copying part of one of John's designs, then changing the dimensions and positions completely and expecting it to work anywhere near the same. If you want your room to work well, then you have to DESIGN it to work well, taking into account what you are doing at every step, and considering what effect each change will have on the entire room. Everything in the room interacts with everything else, to a certain extent, so if you make a change to one thing, you might also need to make other changes to other things, to compensate. You can't just throw 2" of insulation on all the walls and hope it will work out: It wont. You can't look at John's design and figure that, because he used 4" thick insulation, spaced and angled, that you can modify that to use 2" thick, flat up against the wall. That is two totally different things, acoustically. Look at the right rear absorber in that design, for example: The wall itself has ZERO insulation on it! The insulation is in the frame, not on the wall, and the frame is spaced away from the wall at distances varying from 0 to 30 cm. That will absorb a broad chunk of the spectrum very well, in the range of about 225 Hz upwards to about 3400 Hz, and will absorb even lower frequencies fairly well, too, to a certain extent. If that same panel were flat against the wall it (not angled) then it would be a much narrower band device only affecting stuff around 900 Hz or so. The angle and location of the insulation is key to what effect it will have. By the same token, his absorber in the left rear corner is much deeper, reaching 84 cm in places, and therefore acting very well down to at least 100 Hz., and probably even lower than that, since it has TWO 4" layers in it. That's a really good bass trap! I'm sure that John designed each of those devices carefully, to work together and to fit in with the acoustic character that he wanted to create in that room. And I'll bet that the room does NOT sound honky, dull or muddy! I'll bet it sounds fairly even, live, smooth and balanced, across the entire spectrum. It sounds like that because John took the time to DESIGN it to sound like that. You need to do the same, if you want to have a usable room in the end. And if you don't want a usable room with good acoustics, then why would you be going to all this effort, and spending all this money? Brien is right: Maybe you should slow down a bit, and figure out your design better, before proceeding. If you have to move equipment into the room already due to having no other place to put it, then fine, but don't let that stop you from PLANNING the treatment. You can't just throw up some stuff on the walls and ceiling, and hope that it will work. You have to learn the basic principles, and DESIGN it to work. If you don't, then it wont. - Stuart -

I wouldn't have asked the question if I didn't think I was asking the right people. Thanks for the insight. It has been one of my new plans (as of the last five days) to actually move my gear into the room, test, and see what I have. I suppose I am just looking for a turnkey quick solve that I know isn't there. I have been rushed into a situation that, while unpleasant, is gratifying to some extent and I am more than willing to put the work in. I guess I need to be a little more humble as far as where my desires meet reality. It's just really hard to stop working. There are no separations in inner leaf v outer leaf. In other words coupled. Siding>Sheathing>2x4 studs with 3.5" R-13 fiberglass insulation> 5/8" drywall>room. Same with ceiling: Roofing>sheathing>roof members>attic air>ceiling joists with insulation>drywall>room. Floor is crap; floor joists WITH NO INSULATION>subfloor>room. If it helps with your explanations for me, for the record: I have an "American" AA in Music Composition and have been a working recordist and part time live sound eng for around eight years. I am a full-time draftsman, am planning on finishing my AS in Mathematics at the end of this year while trying to finish my prerequisites to transfer to the local university as a dual Physics/Civil Eng. I am trying hard to understand acoustics with my limited knowledge. Your description of my room sound as I proposed to treat it is horrifying. I am stopping all work and am all ears (along with whatever is in between) for the next step. If the sketchup plan is correct, I see no insulation greater than 2.5" with a gap of not more than 1" on any of the "flat sections." I understand that it is not flat up against the wall. According to plan, the rear left is also 2.5" ins. on face with 2.5" on wall with the the greatest angle distance measured to 89.0cm. OK. The reflective surfaces I see as well. I just don't see how close to my ears my environment is that I can use any of it to benefit HEARING what is going on come mix. But then my original problem/question remains: How do I deal with all this while trying to maintain some workable space in a small environment? Screw it all and just trust some headphones? The ceiling is free game if I need some heavily angled and spaced absorbtion. I know I gotten myself into a world uv crap but the ability to design the interior makes me somewhat hopeful if not scared and suspicious. Sketchup plan to follow.

My plan is also trying to incorporate the designs for the wall units which I can no longer find on this forum. You might recall an 8" deep unit to the rear and vertical corner absorbers (were they resonators?) and side wall resonators ala Kendale. The side resonators were omitted due to proximity to mix. Along with increased high absorbers due to smallness of environment. Dimension are within 1/4". The space behind monitors is unused so I can easily bump that out a few more inches if necessary. The reason I have the monitors on stands is because I don't think I would be able to create a face large enough to benefit from infinite baffle or bass correction. If I am wrong, someone please say so. Then I look to the Helmholtz resonators in the Spark One and Click Track designs and think that, if designed properly, reflective-absorbtive surfaces would work in a small environment. I just don't know. Do they need to be forward of their respective sides and only reflect the opposing sides behind listener? Counterintuitive? Then again, so is my blackberry. I just don't understand.

Here are the wall units I was talking about: http://www.johnlsayers.com/HR/index1.htm I was thinking that these ideas might be used and transitions smoothed in a more permanent install. But with listening position at under 4' from side walls, I did not think reflectivity would be in order in any way. I will also draw up some of the other ideas I ended up tossing out to see if I was closer to right on other lines of thought.

There are no separations in inner leaf v outer leaf. In other words coupled. Siding>Sheathing>2x4 studs with 3.5" R-13 fiberglass insulation> 5/8" drywall>room.

OK, so clearly you don't need too much isolation. I'm guessing that structure will get you somewhere in the region of STC-35 to 40? Does that sound about right? So I guess your issues are more to do with treatment than with isolation. Correct?

Same with ceiling: Roofing>sheathing>roof members>attic air>ceiling joists with insulation>drywall>room. Floor is crap; floor joists WITH NO INSULATION>subfloor>room.

So clearly the weak point in your isolation is the floor! That isn't going to get you much better than STC twenty-something...

Your description of my room sound as I proposed to treat it is horrifying. I am stopping all work and am all ears (along with whatever is in between) for the next step.

Id' suggest that "what's next" sould be to buy a couple of good books on the subject, such as Rod's book and the Master Handbook of Acoustics. With those two, you'll have a solid basis for understanding acoustics much better, and being able to design your treatment to do what you want it to do.

If the sketchup plan is correct, I see no insulation greater than 2.5" with a gap of not more than 1" on any of the "flat sections."

Which plan are you referring to? John's "Small Studio" plan? If so, then look here: Those are the sections that I was referring to. They are both broadband bass traps, with different designs and purposes and reasons for existing like that.

I just don't see how close to my ears my environment is that I can use any of it to benefit HEARING what is going on come mix.

I'm not quite sure what you mean by that: It is not about the treatment being close to your ears, but about it affecting the acoustics of the room. What you should be trying to do is to develop a "reflection free zone" around your ears, so that the ONLY thing the hear is the sound that comes directly out of the speakers, without that being muddied up by reflections coming off the front or side walls, or the ceiling, or the desk or equipment, and without it being followed by strong reflections off the back wall, strong modal issues, flutter echo between parallel surfaces, or overall uneven room resonance, or resonance that is too high or too long lasting at any specific frequency. You also want to hear a clean, even, broad, tight sound stage across the entire spectrum, with a good stereo image. There are general rules of thumb that you can use as a first approach to achieving all of the above. Then once you have done all the usual "rules of thumb", you should measure the actual response of your room, see what issues are still left, and deal with them individually. Then test again to see what else might have changed, and deal with those. Rinse. Repeat. Successive approximation. Each time you get closer to perfection. You stop the cycle when you either run out of patience, run out of money, or have it so good already that proceeding further is not really going to gain you anything additional.

But then my original problem/question remains: How do I deal with all this while trying to maintain some workable space in a small environment? Screw it all and just trust some headphones?

Headphones is a lousy option! You can still design and install the treatment as you progress, and still work in the space you have, but realizing that the space you have is not ideal, and is not telling you the truth about your mixes. Each time you install a new piece of treatment you will get closer to that truth.

The ceiling is free game if I need some heavily angled and spaced absorbtion.

How about some photos of what you have up there in the ceiling right now? Maybe one good option would be to do deep absorption over the entire ceiling (since it isn't very high anyway), and keep your floor reflective.

I know I gotten myself into a world uv crap but the ability to design the interior makes me somewhat hopeful if not scared and suspicious.

Well, the good thing is that you realize it, and want to fix it! so now it's just a matter of making the most of what you have, and treating it as well as possible. - Stuart -

thenewforce wrote:

Sarcasm breeds sarcasm. I do not think your post helped me. If there were points which could be better described or completely rewritten from the beginning, I think I would have responded better for a simple "we need more detail/description" Actually, throughout this site, I have found most of what you say, Brien, to be of great benefit. You are one of the posters here that I respect most, as far as what you have to contribute. I think I would have responded the same regardless of who you were. This isn't about personalities. I do however apologize, due to the time constraints I am under, for becoming more frustrated generally. I will have drawings in less than a day.

It wasn't sarcasm...but I guess it looks that way. But you are correct that I can do better as well. Thank you for being man enough to know that both of us may be under some pressure with time:) Maybe I can be of some help in a few more days. Brien

Interior dimensions are 94"x88"x136" hwl with a 36" door on center of long wall. Proposed mix position is centered, 52" from short wall. Monitors are proposed at 48" apart as shown by guides. That is all that is done; it is just a drywalled little box (except for two electrical boxes in ceiling for lights and six single gang boxes for receptacles and one switch controlling the lights). I will get some pictures of it soon. I still use it just as a shed for the moment. It might rain here for the next two days. As soon as the weather clears, I will clear out the room and take some pics.

Here are the pix. Originally the shed was supposed to be a small workshop. Very utilitarian, crappy lights, lots of outlets on two circuits, never really finished. I did repaint it inside, though. Built about five feet away from my house, door facing the house. Hard to take a shot through the door at that distance and get a decent viewing angle. Do I also need to give more construction details? The studs are 24OC. I don't think I said that before. I was talking with a relative who does commercial and residential concrete and he said I would get more isolation by jacking up the floor, insulating the floor, pouring a perimeter foundation and setting the whole thing back down. Does that sound right? Not sure how much isolation I want. It was never really an issue while I was in my house, but it seems that the shed is a lot louder than my old room. And I mean both sound played inside and what you can hear from the outside. I'm going to go out and buy an SPL meter today. On another note, I don't think I can afford any measurement software, though. I found some analyzer java thing from the web. Can I get worthwhile data from using Room EQ Wizard? A serious part of my dilema is figuring out how to treat the door area. The room symmetry is supposed to extend past the listening position but my door is forward of that. So any slot absorbers would either be assymetrical or ahead of my ears. Go to go. More later.

I could be wrong, but I'm thinking that the lack of mass in your structure might actually help the acoustics inside. Low frequencies are the most difficult to tame and I have a feeling a lot of the really low stuff will pass right through the walls, floor and ceiling, eliminating it from the equation on the inside.

Going back a bit:

There are no separations in inner leaf v outer leaf. In other words coupled. Same with ceiling: Roofing>sheathing>roof members>attic air>ceiling joists with insulation>drywall>room. Floor is crap; floor joists WITH NO INSULATION>subfloor>room.

And today:

but it seems that the shed is a lot louder than my old room. And I mean both sound played inside and what you can hear from the outside.

The explanation for "being loud" is above: You have no decoupling on any wall or the ceiling, and your floor is a single leaf, and leaky at that. That's why it is loud. I doubt you are even getting an STC in the thirties. probably high twenties at best.

I'm going to go out and buy an SPL meter today.

That will be very useful! I'd be really interested in seeing how much isolation you actually have, and how loud you are inside and outside. Set your meter to "C" weighting, and slow response.

Can I get worthwhile data from using Room EQ Wizard?

Yes, if you set it up properly and use a good measurement mic and interface with it. "No" if you just use any old mic on a standard PC sound input.

A serious part of my dilema is figuring out how to treat the door area.

Well, your door area is important for isolation, of course, but my guess is that your floor is the major issue with isolation right now. But if you are talking about how to acoustically treat that door, then it seems to be behind your first reflection point, so it should be OK. But you could perhaps put absorption in it, just to be safe. There is a bit of space for a small slot wall behind the door, if you want one. It is not the ideal location for it, but it should still work. You seem to have about 30 inches back there that would be available, before you get to the area where you need your superchunks.

The reason I have the monitors on stands is because I don't think I would be able to create a face large enough to benefit from infinite baffle or bass correction. If I am wrong, someone please say so.

How big can you make the face? 48" across is ideal, but if you can't make that, then anything reasonable will help, to a certain extent. Of course, if all you can get is 2 or 3 inches, then it isn't worthwhile. So how big could you make them? Looking at your rough SKP. it seems to me that you should be able to get at least 35 inches or so, perhaps even over 40", if you plan carefully. That is absolutely worthwhile!

he said I would get more isolation by jacking up the floor, insulating the floor, pouring a perimeter foundation and setting the whole thing back down. Does that sound right?

If you have the money to do that, then a better idea would perhaps be to rip out the existing floor entirely, and set the entire building down on a new slab. That would do wonders for your isolation. Or at least, it would solve your floor problem, and give you a good floor, acoustically, so that you can treat your entire ceiling with absorption. That makes sense. To me, at least. You might even gain a bit of height in your room, which is always good. And since you'd have to re-position the door anyway if you did that, you could make the most of the situation and move it to a better location!

I understand the benefits of soffit mounting the monitors, I just thought I could have more options like progressively testing and treating the room and finding good speaker placement with the stands. I did not want to take the time to figure out the details we are discussing now. Well, I think I might after all give this a shot. So... Maintaining the listening position/speaker geometry I had planned before, I did three quick sketches of differing soffit face widths. 40", 36" and 30". The other two things that changed the most in each design was the width of the center area between the soffits and the distance from the outer edge of the soffits and their respective wall. I am wondering if there are reasons I would want to keep these widths greater and the soffit faces smaller. I do not think I would have anywhere to go as far as angled treatment is concerned with the 40" baffle because it gets me so close to the wall. Is there a width between the end of the soffit and the wall I should be shooting for? Another concern is that my computer monitor would be able to lie close to or set into the 30" design but would have to be set away from the wall on the other two designs. Should this be of concern right now?

You seem to be wasting a lot of space at the front, in the depth behind the center section, (between the soffits). Personally, I'd increase the speaker intersect angle beyond 60 degrees to get better geometry and large soffits, while avoiding those "steps" on the edges of the soffits where they meet the walls. You don't want those: the soffit panels should meet the walls. Increasing the angle would allow you to have a wider center section for your computer screen, and also wide soffit baffles, and also keep the listening position correct. win-win-win. - Stuart -

Ok, I think I understand. A couple more quick SKP files. One is 40" soffits with a 70 degree wide spread firing at the same position behind my 52" starting listening position. The center section has a depth of about 13". The other one, because of the concern of wasted space, pushes the whole assembly back but maintains the 70 degrees and 40" soffits. The drawing is the minimum depth considering the monitors I am using, the enclosure built around the monitors and space for insulation behind the monitor enclosures. A depth of 4.5" in the center. That leaves the starting listening position at around 43" or 32% from front wall. So, dimensions anywhere in between these plans would physically fit in the space. How do I decide where my listening position, and subsequently what the depth of the center section, should be?

Ridiculous. Yeah, I knew isolation was a problem, but not like this. These aren't questions I expect any answers to, just kind of rambling so you all know where I'm at. I need some tips on how and where the readings should be taken. C weighting, slow read...check. I have no idea what I'm doing with this SPL meter thing. Still in my old room, I set up my volume to my normal mixing volume just playing random tracks and, at listening position, the SPL meter reading hovers around 78dB. Good to know. I go walking around my property and the reading is consistently between 63 and 64dB. Is that just the ambient noise around my neighborhood? Not so good, normal, what? So I go walking around my house. All the rooms measure around 51 to 53dB. Wow. What noise floor? Is this noise leaked in from outside? Does leaked sound have a longer decay inside than it would have outside, and therefore seem even louder in the room than it was at the leak point? Will acoustically treating a space lower noise floor? Then I go back to my mix room set the volume back to average volume. I go outside about two or three feet from the exterior wall of my old mix room. The meter reads again 63-64dB. I can hardly discern what's playing inside. Does that mean that nobody notices I'm loud inside my house because it's so loud outside regardless of what I'm doing? I go into my empty shed and the meter read the same as inside my house, 51-53dB. Disappointing to a degree. But, expecting the shed to have lower isolation than the house anyway since it's up off the ground with no skirt of any kind. Well, it is what it is. I still haven't moved my equipment into the shed or bought a measurement mic for room response. Not looking forward to disassembling everything and setting it all back up. Maybe tomorrow looks good to move. More rain Sat.

Alright. While waiting around for the rain to clear, I was going over some design ideas in SKP. I think I have decided to keep my listening position very close to the original 38% starting point with a 70 degree stereo spread, but move the soffit builds closer to the front wall. This would waste less space towards the front of the room while keeping the the speakers firing past my head. I have tried hard to understand the building of soffits and have included a file that gives my proposed design and build. Please give me any corrections. I really have only one question: In this proposal, should I build the two corner soffits separately? or should I build them together? I mean, should the space behind the soffits and in the upper part of the center panel be joined as one continuous sealed space? It seems to me that it depends on what I am going to use the center area for. If for 4" insulation with a 4" space behind it: Separately sealed. If for Slot Resonator: Separately sealed. If solid surface to match soffit faces: One continuous cavity. Am I right?

I want to reiterate my question of what is going on between the two soffits. I have decided that the way to go is a separate, sealed area between the two soffits; where the soffits are, independent of all else, self contained units. From the previous posts, my room has been described, so you all know what I'm working with. I expect to continue testing and adjusting the acoustics of the room as I go. I just want to know if there is a starting point that will be less expensive than simply trial and error. Now the question I have is: How do you decide, at the design stage, whether to have wood covered insulation, cloth covered insulation or a slat absorber designed in the area between the two soffits? Given my situation, can somebody head me in the right direction?

I want to know if I should be working designing the back wall and continuing to test before I finish a cloud over the listening position or if it would give me a better idea of what I still need to do to the back wall if I am testing with a cloud already in place. When starting to design a cloud. I would like to know: 1. What is the acoustic difference between a hard topped cloud and a cloud without a top? 2. When would you use either design? 3. How is the depth specified in either design?