RFZ Mix Room Design. Second Floor.

[jonkr]

Sketchup Room 1.jpg

Hey guys, I'm planning on putting together a private mixing/mastering room in one of my empty rooms. I have attached my design plans so far and would greatly appreciate any advice/critiques, etc..

Budget: $2,500
I have quite a bit of Roxul AFB and OC 703 already but will need to purchase some more. My father and I will be doing all of the labor so no costs there.

Noise/Isolation:

My main goal is to create an RFZ based workspace that provides very accurate monitoring, as little ear fatigue as possible, and allows my work to translate well. I would like this room to also be as comfortable/aesthetically pleasing as possible within budget as I will be spending many hours here. I've never been a fan of very dead, absorptive rooms and prefer studios I've worked in with a fair amount of hard surfaces.

The space is a second story bedroom. I do not intend to isolate the room as the house is in a fairly quiet, rural area and I tend to work at moderate levels. Also, there wont be much recording taking place aside from an occasional guitar or vocal in the same room. I do mostly remote mixing/mastering/production over the internet and that is this room's intended purpose. As of now I can hear more noise than I'd like coming from the living area directly below, but I believe I can bring it down to an acceptable level by adding a solid door in place of the current door which is hollow and not sealed very well. This seems to be where vast majority of noise and leakage is coming from.


The Room:
The Existing space is 13' W x 15' 4" L x 8' H. I plan to remove the drywall from the rear wall and extend the wall back in to the attic, extending the overall length to 17' 2". The original rear wall studs will be left in place and serve as the frame for the inner false wall which will be covered with fabric. This brings the room near Louden's 3rd best ratio according to Bob Gold's calculator. The roof does angle downwards where the wall will be extended and the ceiling will have to follow this angle. The ceiling will be approx. 8" lower where it meets the rear wall. I'm wondering if its better to go 17' 4" to make up for the slight volume loss with the angled ceiling, though 17' 4" is a slightly worse ratio. Maybe I'm just splitting hairs here. The extended area, which will be about 2' deep will be filled with hangers with 4" rigid insulation in front and 3.5" fluffy behind.

The Floor:
The floor is vinyl tile which I plan to leave in place.
As you can see in the illustration, there's a bench/box on the left side of the room where the floor and wall meet that is 18" high x 18" wide and spans the length of the room from front to back (though the picture doesn't really show it spanning the length of the room, it does). I can either make this box smaller (12" x 12") or keep it as a bench and replace the plywood on the side of the box facing the room with rigid insulation and cover with fabric. The duct, however, cannot be moved.

The Ceiling:
The ceiling will be a lightweight drop frame using 1" thick owens corning 703 panels to fill the tile spaces (because I already have several of these panels). Fluffy insulation will fill the cavity above. I planned on making the drop ceiling 8" deep with the purpose of removing floor to ceiling flutter and absorbing first reflections at the mix position. Raising the existing ceiling is not an option due to budget/difficulty/space constraints in the attic above.

L/R First Reflections:
For the first reflection points to the Left/Right of the mix position I plan to use a large sheet of plywood or something similar (not sure what thickness) mounted on the face of inner false wall. 6ft' high x 9ft' long with 1ft fabric covered spaces at the top and bottom to allow low frequencies to enter for trapping. I plan to angle these side walls to send first reflections toward the rear wall to for absorption (or perhaps add back wall diffusion in the future though I don't think my current budget will allow for this). My proposed angles are 11˚ per side totaling a 22˚ angle between both walls. I don't fully understand ray tracing so this angle is somewhat of a guess. I believe there was a thread somewhere on here where Stuart recommended 22.5˚ though I know that doesn't automatically mean the same angle will work for my room.

The Soffits:
The soffit baffles are approx. 39" wide. I don't think the speakers in the illustration are positioned quite at 5/8 baffle width as Stuart recommends but I should have room to play with the numbers and work that out if necessary. I'm only using NS-10s and a Sub right now but plan to upgrade/add the Amphion One18s in the next 6 months or so. Being that these are both passive monitors and both non-ported my understanding is that there would be no reason to make sure the soffits have proper venting. Is this correct?
My plan is to either build the soffits with removable trays or the just build the soffit frames and use the ns-10s as near fields for now and install the amphions later. I plan to have the baffles 6 ft tall with 1ft space above and below for trapping just like the wings.

Mix Position:
The proposed position is ≈33-34% of room length with flush mounted monitors at 60˚ width aiming just behind the head of the listener. Once the back wall is extended I can take REW measurements in the empty room and should have a little room to play with if necessary.

Misc:
As of now there is a single vent pushing air into the room from the rear wall about 1 ft. below the ceiling. I presume I'll need to figure out where to put an air escape vent (front wall?) as I plan to have the room sealed better than it is now. Airtight if possible within my budget.

I plan to have lighting recessed into the drop ceiling.


Questions:

1. Should I extend the room to 17' 2" or 17' 4" considering the longer one is a worse ratio, but the total volume of the shorter one is less than the calculator takes into account due to ≈2' long downward angle on rear ceiling? Am I splitting hairs worrying about a 2 inch difference? Should I not even bother referencing a room mode calculator since my room will be an imperfect rectangle?

2. Will an 8" thick drop ceiling be sufficient at absorbing first reflections above the mix position? I'm willing to go up to 1ft deep at the front half of the room if necessary. Should I instead/in addition use a combination of absorption and plywood angled toward the rear wall absorber? If so, at what angle?

3. Does my plan for L/R first reflection points seem solid? Does the angle make sense? Most of the information I found said the walls together should total 12˚ but I'm confused whether that's just to combat flutter or will that actually be a steep enough to reflect mid/high frequencies away from the mix position. My gut tells me an angle steeper than 12˚ is necessary for this, but my gut also isn't a math wiz.

4. Would there be any benefit to implementing a slat wall rather than a solid piece of plywood at the L/R first reflection points? I like the look of the slat walls, and being on the second floor I'm wondering if slats would be a lighter-weight solution. The problem is that I'm a bit confused about how to implement a slatted wall properly for broadband absorption/directing reflections without creating a high-q tuned resonator.

5. I think I have a pretty good grasp on building the soffits. Is venting necessary in the soffits for any reason if I only plan to use passive monitors with the amps in my rack?

6. I planned to slat the small, angled sections near the rear wall with the intention of it contributing to keeping some high-mid energy alive in the room and breaking up flutter in that section as well as for aesthetics. I think it probably won't be necessary to have the angles as steep as I made them in the illustration. I suppose this is sort of an extension of question #4. How would I properly implement slats for the purpose I described?

7. Is there anything in the illustration that seems off or unnecessary? All constructive comments are appreciated.


These are my biggest questions for now. I think once these uncertainties are ironed out I'll be much closer to having a useable design.

Thanks in advance to anyone who can offer some insight.

Best Regards,

Jon

[Soundman2020]

What an excellent first post for a new studio thread! I wish everyone would have such a clear, well-researched, well-though-out first post!

I've never been a fan of very dead, absorptive rooms and prefer studios I've worked in with a fair amount of hard surfaces.

Good! Because the specs for a control room are quite clear: The decay times, frequency response, and other acoustic characteristics are laid out fiarly clearly in documents such as ITU BS.1116-3 and EBU Tech-3276, showing very much "not dead" response. The overall decay time is set based on the size of the room (air volume), and is intended to be neutral: neither dead nor live, but rather natural sounding, open, clean. The days of the stuff, claustrophobic sound of the famous LEDE rooms of the 70's and 80's are long gone. As long as you design and tune your room to meet those specs, you'll be fine. Here's an example of such a room, along with the acoustic analysis: http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20471 You may have seen that already, but if not then it's worthwhile taking a look at the actual web site for that studio, where there are many more details.

I do not intend to isolate the room as the house is in a fairly quiet, rural area and I tend to work at moderate levels.

Not too much noisy stuff going on around your house, on the outside? Wind, rain, thunder, hail, aircraft flying over, sirens, neighbors, traffic, etc?

As of now I can hear more noise than I'd like coming from the living area directly below, but I believe I can bring it down to an acceptable level by adding a solid door in place of the current door which is hollow and not sealed very well. This seems to be where vast majority of noise and leakage is coming from.

Assuming your current door is a typical house door, hollow-core with thin wood on each side, that new door will probably make a significant difference, especially if you take care to add full-perimeter seals all around the edges, and also to seal the casing into the wall rough opening very well. For a heavy door, you will need more hinges than you have on your current door, to ensure that it hangs straight and does not bend, twist, or warp as you open and close it, or sag over time. Use heavy duty hinges.

The Existing space is 13' W x 15' 4" L x 8' H. I plan to remove the drywall from the rear wall and extend the wall back in to the attic, extending the overall length to 17' 2".

Sounds like it will be a decent sized room. That also implies an overall decay time of around 250ms. Not dead!

The roof does angle downwards where the wall will be extended and the ceiling will have to follow this angle. The ceiling will be approx. 8" lower where it meets the rear wall.

Have you considered flipping the room around the other way, so the low side is at the front, where the speakers are, and the high side is at the rear? In general, a room should not get smaller towards the back: it should get larger or remain the same, to reduce the compression effect as the sound waves approach the rear wall. In this "flipped" scenario you would have to take out the studs from the current "rear" wall, but that's probably not a big deal. You can re-use all that wood to build your soffits.

I'm wondering if its better to go 17' 4" to make up for the slight volume loss with the angled ceiling, though 17' 4" is a slightly worse ratio.

If you can get significantly more volume in your room at the expense of a small loss in the ratio, I'd say "Go for it!" Ratios are important to a certain extent, but in my book, room volume is more important. As long as it would not make your ratio terrible (eg, two dimensions identical or exact multiples), then that's fine.

The floor is vinyl tile which I plan to leave in place.

As you can see in the illustration, there's a bench/box on the left side of the room where the floor and wall meet that is 18" high x 18" wide and spans the length of the room from front to back (though the picture doesn't really show it spanning the length of the room, it does). I can either make this box smaller (12" x 12") or keep it as a bench and replace the plywood on the side of the box facing the room with rigid insulation and cover with fabric. The duct, however, cannot be moved.

I would try to make it smaller if you can. Once again, room volume wins out, if you can get it at little cost in some other aspect. There's also the issue of symmetry: that box is upsetting your room symmetry a bit, and making it smaller would improve that.

L/R First Reflections:
For the first reflection points to the Left/Right of the mix position I plan to use a large sheet of plywood or something similar (not sure what thickness) mounted on the face of inner false wall. 6ft' high x 9ft' long with 1ft fabric covered spaces at the top and bottom to allow low frequencies to enter for trapping. I plan to angle these side walls to send first reflections toward the rear wall to for absorption (or perhaps add back wall diffusion in the future though I don't think my current budget will allow for this). My proposed angles are 11˚ per side totaling a 22˚ angle between both walls. I don't fully understand ray tracing so this angle is somewhat of a guess. I believe there was a thread somewhere on here where Stuart recommended 22.5˚ though I know that doesn't automatically mean the same angle will work for my room.

OK, this is the first place where your plan is not doing so well: That angle iw way too small for that room. The angle you need can be determined by "ray-tracing", which basically just involves shooting out some imaginary lines from the acoustic center of your speaker, to see where they go. If they get too close to your head, then move whatever it was that they reflected off, until they are no longer a problem.

If you do that in your picture above, shooting out rays at a few angles and bouncing them off those side panels, you'll see that some of them will get directly to your ears.

To do the ray-tracing, start by drawing a line straight out from your speaker, perpendicular to the front panel (90° angle). You already show such a line in your model. Now shoot out a couple more lines like that, from the same point on the face of the speaker, one on either side of that "axis" line, but offset by an angle of 5°. Wherever that line hits a wall or other hard surface, make it "bounce", and see where the bounce goes. You "bounce" the ray by making it reflect off the surface at exactly the opposite angle. So for example, if a ray hits a wall at an angle of 37.3° from perpendicular, then draw another line emanating from the exact spot where the first one hit the surface, but at an angle of MINUS 37.3° (in other words, -37.3°, or 37.3° going the other way.

If you do that with both of the lines that are 5° away from the original speaker axis, and they don't get close to your head, then repeat the entire sequence: send two other rays but now at an angle of 10° from the original axis line, and see where they go. Then repeat at 15°, 20°, 25°, etc. There's not much point going beyond 60° or so usually, since at high angles off-axis it will be mostly lower frequencies (less directional, less "ray like", less specular) that you are looking at, but even so it might be worthwhile trying one at 80°, just to be sure.

If any of your bounced rays get within a foot or so of your ears, then angle the surface that it bounced off some more and try again. Depending on how good you want the room to be, you could extend the cut-off point to maybe 2 feet (instead of one foot), but the larger the "reflection free zone" you want, the more difficult it becomes to angle the surfaces.

The soffit baffles are approx. 39" wide. I don't think the speakers in the illustration are positioned quite at 5/8 baffle width as Stuart recommends

That's fine: as with most aspects of studio design, there are always compromises that you'll need to make. There are a bunch of "theoretical ideals", and then there's reality! Reality pretty much always wins, and trumps "theoretical ideals"...

I'm only using NS-10s

Any chance you can upgrade now, before you build the room? NS-10's are not exactly know for smooth response and deep bass....

Being that these are both passive monitors and both non-ported my understanding is that there would be no reason to make sure the soffits have proper venting. Is this correct?

You will still need venting. Converting electrical power into acoustic power is extremely inefficient. About 99% inefficient, to be more exact. In other words, if you pump a hundred watts of electrical power into a speaker, you'll only get about one watt of acoustic power out of it. The rest mostly goes into heat... It is dissipated in various forms, inside the drivers. The heat needs to go somewhere, so you do need to provide cooling. OK, so it's not a huge amount of heat, but it is still there.

My plan is to either build the soffits with removable trays or the just build the soffit frames and use the ns-10s as near fields for now and install the amphions later.

I plan to have the baffles 6 ft tall with 1ft space above and below for trapping just like the wings.

That's fine, but you could probably leave more space up top. If the top panel of your soffit enclosure is at around 6 feet, you'd have a nice large 2 foot zone above that for bass trapping.

And the" one foot down below" is just to allow sound to get into the bottom region of the soffit, below the shelf: inside, behind the front panel and under the shelf, there's plenty of room. I usually put hangers in there.

The proposed position is ≈33-34% of room length with flush mounted monitors at 60˚ width aiming just behind the head of the listener.

Sounds fine.

As of now there is a single vent pushing air into the room from the rear wall about 1 ft. below the ceiling. I presume I'll need to figure out where to put an air escape vent (front wall?) as I plan to have the room sealed better than it is now. Airtight if possible within my budget.

Yes! And you'll probably need some type of silencer box on both of those vents....

I plan to have lighting recessed into the drop ceiling.

ummmm... How will you mount that? You said your drop ceiling tiles are made entirely of OC703, which certainly isn't rigid enough to mount lights on...

1. Should I extend the room to 17' 2" or 17' 4" considering the longer one is a worse ratio,

Yes.

2. Will an 8" thick drop ceiling be sufficient at absorbing first reflections above the mix position?

To be honest, I wouldn't do it that way. It's not a BAD idea, but if you want a true RFZ style room, then I'd suggest that you hang a hard-backed cloud at an angle up there, and do the ray-tracing thing again to figure out the best angle. Sound moves in all three dimensions, not just two. You could do your 703 drop ceiling for the rest of the room, behind you, but I'd do a cloud over the front part. You CANNOT create a reflection free zone with absorption alone...

Should I instead/in addition use a combination of absorption and plywood angled toward the rear wall absorber?

Yes, but in the form of a hard-backed cloud, not just a sheet of plywood.

If so, at what angle?

The one that creates a reflection free zone around your head! In other words: you'll have to ray.trace that to figure it out. It will NOT be the same angle as for the walls.

3. Does my plan for L/R first reflection points seem solid? Does the angle make sense?

No, and no.

Most of the information I found said the walls together should total 12˚ but I'm confused whether that's just to combat flutter

Exactly. 12° us what you need to successfully deal with flutter echo.... but NOT what you need for RFZ.

My gut tells me an angle steeper than 12˚ is necessary for this, but my gut also isn't a math wiz.

Your gut is right in this case!

4. Would there be any benefit to implementing a slat wall rather than a solid piece of plywood at the L/R first reflection points?

Not at the reflection points, no. Slat walls are tuned, and I'm not a big fan of having tuned devices close to your ears, since they color the sound...

I'm a bit confused about how to implement a slatted wall properly for broadband absorption/directing reflections without creating a high-q tuned resonator.

It depends on how you tune the wall, and also on the "open area" of the wall (the frontal area of the slots between the slats), as a percentage of the total wall surface (the frontal area of the slats). If the percentage open area is less than about 5%, the wall tends to act as though is tuned to a set of specific frequencies (given by the tuning of the individual slots). If the area is more that about 10%, then it acts more as if it where a broadband absorber covering the range of tuning of all the slots. It's not a hard-ad-fast rule, but it gives you an idea.

Is venting necessary in the soffits for any reason if I only plan to use passive monitors with the amps in my rack?

Yes. See comment above.

6. I planned to slat the small, angled sections near the rear wall with the intention of it contributing to keeping some high-mid energy alive in the room

You will probably need to extend those slats across the entire rear of the room, in front of the bass trapping. If not, you'd be loosing way too much of the high end. Another option is to cover the insulation with some type of foil, such as plastic. You can tune the high-frequency return like that, by carefully selecting the plastic thickness and percent coverage.

- Stuart -

[jonkr]

Thanks so much for the help Stuart! You've made things much clearer for me.

The ceiling:
I didn't describe the ceiling clearly. The entire ceiling is 8' with no angle. The part of the rear ceiling that will be extended into the attic will have a slight angled drop. I've attached an illustration to help clarify.
Even though the wall is being extended the studs of the original wall will not move. Only the drywall will be removed as the studs of the original wall help support the roof of the house.

Screen Shot 2018-01-09 at 6.23.57 PM (2).png

I do not intend to isolate the room as the house is in a fairly quiet, rural area and I tend to work at moderate levels.
Not too much noisy stuff going on around your house, on the outside? Wind, rain, thunder, hail, aircraft flying over, sirens, neighbors, traffic, etc?

Isolation:
There is occasional noise from boats on the river about 500 yards away. Also, rain is not infrequent but not terribly frequent either. Neighbors, traffic, and aircraft are not an issue. I've weighed the pros and cons of going for significant isolation and I believe doing it properly is going to go far beyond my budget and what my father is willing to do (this is his house). Also, the oil and gas companies have been buying more and more people out the past few years and may very well look to buy this land in the not so distant future. This is another deterrent for me to spend additional time, money, and labor to achieve proper isolation.

There was a closet in the rear corner we removed already which revealed several areas that weren't sealed well. We're going to add fresh sheets of drywall in those areas and mud/caulk well. That along with a solid, sealed door I believe should give me enough of a reduction of outside noise to work comfortably.

L/R first reflections:
Thank you for the explanation on ray tracing. I understand now. I will modify my angles and post the updated sketch.

I'm only using NS-10s
Any chance you can upgrade now, before you build the room? NS-10's are not exactly know for smooth response and deep bass....

Speakers:
I may be able to upgrade the speakers but it won't be the Amphions as those are out of budget at the moment. I'm thinking about a pair of Equator D8s. (I will vent the soffits as well)
Definitely gonna keep the NS-10s as a second pair because I'm very familiar with them.

Venting:
I plan to build an inline baffle between the hard rear wall and the false wall. Is it bad to have the baffle right at the outlet/technically inside the room? Going to figure out something for the return air on the front wall. Should't be too difficult.

I plan to have lighting recessed into the drop ceiling.
ummmm... How will you mount that? You said your drop ceiling tiles are made entirely of OC703, which certainly isn't rigid enough to mount lights on...

Lighting:
I planned to attach the light fixtures to the hard ceiling above making them only appear to be supported by the 703 panels.

2. Will an 8" thick drop ceiling be sufficient at absorbing first reflections above the mix position?
To be honest, I wouldn't do it that way. It's not a BAD idea, but if you want a true RFZ style room, then I'd suggest that you hang a hard-backed cloud at an angle up there, and do the ray-tracing thing again to figure out the best angle. Sound moves in all three dimensions, not just two. You could do your 703 drop ceiling for the rest of the room, behind you, but I'd do a cloud over the front part. You CANNOT create a reflection free zone with absorption alone...

Quote:
Should I instead/in addition use a combination of absorption and plywood angled toward the rear wall absorber?
Yes, but in the form of a hard-backed cloud, not just a sheet of plywood.

I'm confused about what you mean here. I thought a sheet of plywood with absorption on the front would constitute a hard backed cloud?
However, I do understand about ray tracing the cloud angle. I will add that to my next sketch.

6. I planned to slat the small, angled sections near the rear wall with the intention of it contributing to keeping some high-mid energy alive in the room
You will probably need to extend those slats across the entire rear of the room, in front of the bass trapping. If not, you'd be loosing way too much of the high end. Another option is to cover the insulation with some type of foil, such as plastic. You can tune the high-frequency return like that, by carefully selecting the plastic thickness and percent coverage.

I like this idea. However, I'd imagine the rear wall would then have to be angled in order to prevent flutter between the rear wall and the parallel section between the front the speakers.
I have no problem angling the rear wall a bit if necessary. Just trying to understand clearly.

This brings up another question. What should I do on the front wall between the speakers? Slats? Or is that to close to the listening position for slats? I plan to mount a 32 inch video monitor there.

Thanks again for the help Stuart. I realize you and the other professionals on here have no obligation to share the knowledge that you do. I am beyond grateful.

[jonkr]

Ok, so here is my updated plan...

Sketchup Room 1B.jpg

I've ray traced first reflections and adjusted soffit wings so that the closest reflection is 19" from engineer's head at mix position.

I've added fluffy insulation as opposed to hangers based on DanDan's recommendation over at gearslutz. To my knowledge either approach should be more or less interchangeable in this instance and I'm thinking stuffing the front cavity with fluffy might simpler.

I've decreased the size of the duct box to be as small as possible at 12" high and 12" wide.

All sidewalls from listening position on back have been changed to slat walls at 50% coverage as to preserve some HF energy while preventing flutter. I was thinking of covering a higher % but not sure as there seem to be many varying opinions when it comes to slat walls.

I'm thinking of adding a piece of glass to the left of the listening position to preserve some natural light during the day. Any inherent or obvious issues with the way I have this implemented in the illustration?

Studio Ceiling cloud.jpg

As for the ceiling cloud I do not have enough ceiling height to get the angle I need without cutting in heavily to the height of my soffit bezel. I've drawn out the best solution I could come up with with. I think the illustration can explain it better than I can in writing. Im basically using two different angles in attempt to send first reflections away from the listening position. I realize the idea in the illustration may cause issues with desk reflections. Any thoughts or better ideas are very welcome.

[thedavidlim]

Following.

[Gregwor]

I had this same issue trying to figure out my angles and ended up sliding my entire front wall towards myself. That seemed to solve all of my issues.

EBU 3276 states that the distance from your head to the line between your speakers should be +- 0.9 times the distance between the two speakers. We all don't have the luxury to build a room to their specs, but what I'm implying is that you should maybe adjust your front wall/soffit walls closer to you to fix your ceiling angle dilemma. Oh the woes of short ceilings hey

Hopefully that works for you!

Greg

[jonkr]

I had this same issue trying to figure out my angles and ended up sliding my entire front wall towards myself. That seemed to solve all of my issues.

EBU 3276 states that the distance from your head to the line between your speakers should be +- 0.9 times the distance between the two speakers. We all don't have the luxury to build a room to their specs, but what I'm implying is that you should maybe adjust your front wall/soffit walls closer to you to fix your ceiling angle dilemma. Oh the woes of short ceilings hey

Hopefully that works for you!

Greg

Thanks for the reply, Greg. I think I'm just going to use two hard-backed clouds instead of one. I haven't ray traced yet with two clouds but I'm confident I should be able to work something out. Also, the framing for the front (soffits and wings) went up today so I'm going to have to work with it like it is at this point.

I have a few questions of some things I'm still not 100% sure about but so far it's coming together nicely. I also did baseline measurements yesterday and frequency response in the empty space already looks better than my old room did with treatment I suppose this is due to superior dimensions. The waterfall is a disaster, of course.

Gonna do a little more research and get back to you guys with questions and photos.

[Gregwor]

I'm glad it's measuring out good, but I will repeat what I've seen the pros write here countless times:

"Stop building NOW. Get all of your plans solidified 100% before you build."

You may have shot yourself in the foot by building your front wall. I really would figure every detail out, THEN build. It's easy to adjust something in SketchUp, it's much harder to rip a wall down and rebuild it in real life.

And another classic saying around the forum, "pictures or it didn't happen".

Share pictures please.

Greg

[jonkr]

I plan to finish rear wall hangers today along with all insulation and maybe begin on the drop ceiling if I have time.

Here are some pics of my progress so far:

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[jonkr]

Question: Considering I don't plan to buy a pair of speakers to flush mount until another 6 months or so, should I leave the soffit area soft and simply cover with fabric? I will be using nearfield NS-10s ffor the time being which will be pretty much be located in front of where the flush mounted monitors would be. Will it mess up up the integrity of the room if I do it this way for now? Would this help or hurt sbir? Either way it's no problem to do. Just wondering if anyone has an idea what the best direction would be until I buy a pair of speakers to mount in the wall. If it's an unpredictable factor I can always test both ways.

[Gregwor]

Why don't you design it so that you can adapt to new speakers without too too much hassle. Ex: build a bezel to go around your speakers that you can cut out to accommodate different speaker shapes and sizes without having to replace the entire soffit wall front. For now, why don't you flush mount the NS10s? I personally love the sound of my NS10's. I think I'm going to pick up a pair of Barefoot MM45's for my flush mounting so that I can still have that NS10 sound (plus others) all in one flush mount package.

Greg

[jonkr]

Why don't you design it so that you can adapt to new speakers without too too much hassle. Ex: build a bezel to go around your speakers that you can cut out to accommodate different speaker shapes and sizes without having to replace the entire soffit wall front. For now, why don't you flush mount the NS10s? I personally love the sound of my NS10's. I think I'm going to pick up a pair of Barefoot MM45's for my flush mounting so that I can still have that NS10 sound (plus others) all in one flush mount package.

Greg

Thanks for the repIy Greg. I very well may go that route. That was actually my first plan. For some reason I was under the impression that Stuart had advised against flush mounting the NS-10s, but upon re-reading his response I see he simply suggested upgrading if I could. Though, in all honesty I was planning to take some time learning more about soffit design. I thought I had a firm grasp on it, but lately it seems the more I read the more questions I have.

One question I have is about the front middle section between the faces of left and right soffits. I had planned a slat section, but I think that might not be a great idea considering I'll be fairly close to it. Should I just use a sheet of plywood?

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I'm also a little uncertain about what to do with the the sidewalls in the back half of the room. I'm thinking plastic layer covered with fabric in the middle section and horizontal slats with no plastic toward the rear corners continuing on the rear wall. This is probably a terrible explanation. I've included a picture to hopefully make it clearer.

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Is it ok for slats to all be the same size with same slot gap? One of the pros at gearslutz suggested 50% coverage, but I'm still uncertain about how to implement that properly.

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[Paulus87]

Hey hows it going with your build? any updates?

[jonkr]

Hey hows it going with your build? any updates?

Some things came up and I never got to really “finish” it.

Ironically it gave me plenty of time to research and gain a lot more knowledge about things I could’ve done better initially (all of which are correctable with some effort). I’ll update with some photos a when I’m on my desktop.

I originally had NS-10s flush mounted, but I work a lot in modern, bass-heavy genres (hip-hop, pop, r&b) and they weren’t really cutting it for obvious reason as Stuart pointed out earlier in this thread.
I ended up buying a pair of APS Klasiks but have yet to switch them out with the NS-10s. They aren’t quite in the same ballpark as the Barefoot MM 26(7)s or ATCs I’ve worked on, but undoubtedly the best sounding monitors I’ve heard under $1500. I plan to eventually update the soffits with a pair of MM45s but I think the Klasiks will be more than sufficient until I have the budget together for that.

I wound up building the speaker support system a little differently than the methods I’ve come across on this forum. Details here: https://youtu.be/oZ44hM7sRj8

I have been getting work done in the room and my clients seem to be happy, though I don’t find that suprising considering I was working in a much worse space before. Still taking my higher end clients’ material to pro rooms.

Anyway, I plan to get back to work soon and hopefully have it done by the end of the year. I’ll be sure to update this thread as with some photos ASAP and I’ll post some REW measurements when I get the Klasiks installed.

[Soundman2020]

I wound up building the speaker support system a little differently than the methods I’ve come across on this forum. Details here:

He mentions some points about speaker mounting, but then doesn't show how he implemented them! That framing, for example, is way too flimsy. Soffits need very rigid, solid, massive framing, or you'll end up with vibration in the structure itself, which is then transmitted into the walls, ceiling and floor, so you get early-early sound arriving at your ears BEFORE the direct sound from the speaker...

Also, he didn't mention what frequency he tuned that floating system too, but there doesn't seem to be enough static deflection on those isolation mounts, and that's not what they are designed for anyway. Those are meant for hanging entire ceilings! Not speakers...

He also doesn't show how he plans to deal with the issue of the speaker MOVING around so much when played loud, thus creating Doppler effects in the mids and highs. The woofer moves a LOT: there's lots of inertia in that, which is normally counters due to the speaker sitting in a rigid surface (on a stand, for example) or being held rigidly in place by an enclosure box (when soffit mounted). But here, it is free to swing any way it wants as the woofer shoves it around. It could swing several mm, potentially. When the wavelength is just 20, 30, 40, 50mm (7kHz to 20 Khz), and the speaker is swinging 4, 5, 6 or more mm back and forth, bouncing up and down, wobbling left and right due to not being held properly in place (as shown in that video), that's a huge difference! More than 10% of the wavelength!!! You do indeed get Doppler issues in the sound: the sound source is moving as the sound is playing, so each subsequent wave comes from a slightly different point in space... Not good. The CORRECT method for floating a speaker is to only allow it to move a fraction of a mm, on suitable resilient rubber mounts of some type, correctly dimensioned and with the correct deflection. Sorbothane is the best stuff for this. Plenty resilient, plenty of damping (which is good but also bad... ), but with good soffit design using Sorbothane, the speaker will only move less than 1 mm, even under the highest levels of woofer full-stroke movement, while still being fully decoupled and truly floated.

He also didn't say how he plans to prevent the speaker from banging into the soffit baffle, as it swings around...

He also suggest using weather-stripping, but doesn't say how, and shows no calculations as to how that would affect the resonant frequency of the mounting system, or the damping...

To be honest, when you mount your new speakers, I would suggest NOT doing it that way! There's a reason you never see that method used in pro studios... or semi-pros studios... or high-end home studios!

There's a hell of a lot of videos on YouTube from well-meaning but acoustically ignorant people, that actually show the best way to NOT build your studio, if you want it to work well.

Soffit mounting isn't hard to do right. A while back I wrote a post with guidelines for setting up any speakers in any room, and the part about soffits (from point number 8 onward; the previous points were for stand mounted speakers) goes like this:

8 ) Make the front baffle of your soffit as wide and tall as you can, within reason. The width should be at least three times the diameter of your low frequency driver. In other words, if you have a speaker with an 8" woofer, then you want the soffit baffle to be at least 24" (60cm) wide. Wider is better. If you have a three-way speaker where the tweeter is in the middle, between two identical woofers, then the "diameter" is the distance from center to center of the woofers.

9) Do not put your speaker in the middle of the soffit baffle: Offset in both directions. In other words, the distances from the acoustic center of the speaker to each edge of the baffle should be very different, by at least 20%. So for example if your speaker axis is 30cm from one side of the baffle, it should be more than 36cm from the other side, less than 24cm from the bottom edge, and more than 44cm from the top edge. (Rough distances, for illustration only...). Larger differences are generally better. Try to get it at the 2/5th location side-to-side, if possible.

10) Make the baffle as massively heavy as you can, and as immensely rigid as you can.

11) Make the structure inside the soffit (the framing that holds the baffle and speaker in place) as rigid and massive as you can.

12) Mount the speaker inside an enclosure box that is either a very tight fit, in order to keep the speaker rigidly fixed in place, or mount it on suitable resilient mountings, to completely decouple it from the the box. Carefully choose the properties and dimensions of that resilient material, to make sure the speaker is still decoupled down to at least one octave below the speaker's low cut-off frequency. Sorbothane is the best resilient material for this. Do the calculations carefully to get the frequency right, with the correct static displacement.

13) Take into account that speakers need a lot of space behind them for cooling, and a path through the soffit for cooling air to flow. You also need space at hte back for acoustic reasons.

14) Rear-ported speakers need special attention: Do not overload the rear port, acoustically, with an enclosure box that is too small, or un-ventilated, or un-damped. Leave more space at the back of a rear ported speaker, and damp the port itself very lightly.

15) Damp the hell out of the soffit interior! Fill it entirely with suitable damping if you want, except for the cooling path.

There's more to it than that, but it's a start!

So when it comes time to update your speakers, I'd suggest following those, and also use the methods you see here on the forum: they really do work!

Anyway, I plan to get back to work soon and hopefully have it done by the end of the year. I’ll be sure to update this thread as with some photos ASAP and I’ll post some REW measurements when I get the Klasiks installed.

Cool! Looking forward to that!

If you want, do some REW tests now! That will give you a good point of comparison, to check your future upgrade against. It might even highlight other issues that can be fixed at the same time as the upgrade. Here's how to do the REW tests: http://www.johnlsayers.com/phpBB2/viewt ... =3&t=21122 . If you feel like doing that now, and posting the MDAT file some place I can download it, then I'd be happy to take a quick look for you, and see if there's some things that can be improved easily.


- Stuart -