Greetings. First post here. Decade long lurker... just finally getting social.
I've read the rules. I've read thousands of posts. I've read Rod's book. I'm working my way through MHoA at the moment. I'm 3 days in to learning sketchup. Thank you everyone for all of the wonderful information you've made available here.
Grand introduction aside, I have a bit of a specific question concerning flush mount RFZ control room design when the engineer is limited in front-wall distance.
I work using a 55" 4K monitor... that's 3840x2160 resolution. The physical size, screen real estate and ppi is very similar to having four ~27" monitors in a 2x2 grid, for reference. To maintain legibility of smaller text and graphics, my optimum head placement must center around 4 ft. from the LCD.
In working through rough designs for a near-future room, I found that a 6 foot speaker spread with standard 30 degree angles fits rather perfectly. I based a sample room on Sepmeyer's 2nd ratio and arrived at 12H x 15.36W x 18.48L as a starting point. I have attached images of this mock-up.
For reference, my monitors are Adam S3X-Vs on IsoAcoustics on Argosy Classic 36" stands. All are modeled accurately in the sketchup capture, along with the 55" LCD. I think it works well as a primer.
From there, I began structuring a flush mount RFZ design around my basic dimensions... as this is ultimately where I want to wind up.
Alot of commentary on RFZ designs seems to suggest that its very room-specific in its layout - that is to say there's no golden formula. That makes sense. So, piecing together what common themes I could find, I designed a graduating angle 5 piece front wall. Raytracing seems to suggest all is well... I even raytraced a couple of fully 3D reflections off my sidecar racks with positive outcomes. Here is that evolution:
From here its important to note that I'm rather bound to the geometry of my 6-foot speaker spread. Moving the speakers farther apart will require myself to move back to maintain an equilateral triangle. As previously hinted, I cannot move back any further, as my LCD screen will become illegible. Obviously moving the LCD back with me is also a non-option, as it would block half of the incoming sound waves.
My questions then are as follows:
1: Considering the close distance of the speakers to the LCD (and corresponding flat front wall), am I disturbing the "infinite baffle" too early to fully benefit from it? Most designs I see have a window in the location of my LCD (a depression rather than outward projection) and speakers placed farther outward in the baffle. The LCD depth is not accurately modeled, and it would protrude a couple of inches from the wall... though it would seem any extreme off-axis sound would still meander its way out of the RFZ without problem. Flush mounting the LCD is an option as well.
2: I placed my rear outside stud-frame 4" from the inner stud-frame (a total air gap of 11"). The Adam speakers are quite deep (approx 11.5"), and are within 5/8" of the outer studs. I see this as obviously unacceptable as the flush-mount boxes will need additional space. Given my requirement to NOT move the speakers outwards, I take it my only solution is to space the outer stud-frame farther?
3: Does anybody have real-world experience with flush mounting active Adams? In some sense they are perfect for it (all EQ controls are located on the front), though they are relatively warm-running and I recall reading somewhere that the beveled front edges make proper flush mounting difficult.
Thanks so very much.
Practical considerations for flush mnt RFZ using 4K, 55" LCD
Originally posted at johnlsayers.com, topic 19307.
Bonus question:
It occurred to me that since my front wall had effectively moved forward in the RFZ design, I was now far away from the 38% guideline... sitting nearer to 25%.
In an effort to remedy that, and to experiment with placing the speakers in a more traditional spacing, I wound up with this:
As is obvious, the LCD is the crux of my issues. I'm starting to think that a true RFZ splay with flush mounts can't be achieved with my limitations?
Color me confused.
2 week bump. Thanks for looking.
Sorry to say, but I think what you want is too much at the same time. If you want a giant screen like that in 4k resolution, it does not mean you can push it way further back, because the best distance will still be identical (70 - 80 cm), at most a little higher (maybe 1.2m). Way closer than your speakers should be!
So, your monitor will always be in the way of your speakers! I have the same Adams, so I know the recommended listening distance is about 2m! If you stay with stereo, I would definitively go for a little bit more. I went for 1.8m, just to get the surround circle working in my room.
viewtopic.php?f=1&t=17825&start=30
On page 3 you can see how I got a larger monitor working, but this is only a secondary monitor for playing movies (film music composer). My new first monitor is a 2k touchscreen, which will be mounted to the desk, tilted about 45 degree. This was IMHO the best idea of having a big screen without compromising the sound. I also have a third screen with a monitor arm that can be added, if I need it. But when it comes to mixing I plan to stay with the tilted one. So, for bigger distance I would recommend a normal full HD with bigger size. That way you will be able to read something from it! ;-)
Dang, wrote a reply but had to switch into Airplane Mode and it went POOF.... retyping:
Hi! Thanks for the reply and thread link. I skimmed the thead for a moment but my flight is about to depart... I'll read it thoroughly once I land.
A few quick counterpoints:
I have found the optimum viewing distance on my 4K panel to be approximately 4 ft (1.2 meters).... definitely not 70-80 cm. Due to the width of the panel (49" if I remember correctly) speakers placed to the side are naturally 6 ft apart. At 30 degree angles the listening position is indeed 6 ft (1.828 Meters) from the speakers. Both the rectangular and RFZ sketchups feature these measurements.
Perhaps thats a tad short of optimum for the Adams, if we're aiming for a 2 meter minimum, though we're talking a difference of inches (5.6" to be exact). That seems like its well within the region of acceptable compromise? Especially considering I can simply roll my chair or lean my head back 6 inches for more critical listening. In truth I tend to do this anyhow, as it mentally disengages me from the visual / LCD aspect.
I do understand, of course, that switching to 1080p would allow me to sit much further back. But... its just not gonna happen. I am a power user when it comes to computers ("massive geek" sound better?), and with regard to studio specifics I tend to use high track counts, lots of plugins, lots of soft synths, use RME TotalMix extensively, edit heavily, work with MIDI constantly, etc etc. That, and I deplore scrolling and window juggling. All told I am screen-real-estate junkie. In fact, my actual design has TWO 4K screens - the other being mounted above and with an angle. I removed the second screen for the sake of simplifying my current questions. =)
Honestly, trying to work at 1080p at this point feels like trying to get things done on a Nintendo Gameboy. ;)
I believe my initial measurements are within usable territory, if slightly compromised from optimal. The questions remain in regard to my RFZ geometry, and perhaps a better way to acheive what I'm after. I am mostly concerned that the wall segments which house the speakers have very little horizontal area (and thus mass) before meeting the center wall segment. It seems that there would be a minimum necessary mass on all 4 sides of the speaker in order to achieve the "infinite baffle" effect?
Thanks!
Well, I wrote 1.2 meters at max, didn't I? Although I suppose that would be stretching it a little to far. I am pretty sure you will get eye fatigue faster with this distance, since objects on the screen will be smaller, I think. But that is for you to decide, as you have this monitor and probably know best, what is good for you.
The leaning back for critical listening on the other hand sounds more like you really want this screen and talk yourself into that it is going to work. For a good stereo image you must be on spot with your average ear position.
If you really want this to happen, I would take a look at Johns designs for angles greater than 60 degree. He often wrote here, he was using 90 degree angles for stereo and that it would work well - he even seems to favor it due to a bigger sweet spot. Maybe he can share his opinions about it, as I don't want to speak on behalf of him. But that should make it easier to push the speaker walls further away, while keeping the screen at 1.2m distance.
Hi there " ewb", and welcome! :)
Sorry about the belated response: lots going on right now.
Right. But there are some general rules that you should take into account.Alot of commentary on RFZ designs seems to suggest that its very room-specific in its layout - that is to say there's no golden formula.
There's a problem with the way you are doing the infinite baffle section of the soffits: they are not wide enough, and the space between the edge of the speaker and the large screen is too small. Ideally, the speaker should be about centered at about 2/5 of the width of the infinite baffle. You also do not need to angle the rear part of the wall, behind the mix position. That just wastes space. That section can be flat.I designed a graduating angle 5 piece front wall.
so then forget the "equilateral " part! I promise, you won't be arrested by the triangle police! :) You can angle your speakers at a higher or lower angle, within reason. You can go down to about 25° and up to about 45° if you have to. As long as you realize that you will be changing the shape of the sweet spot, and allow for that, you'll be fine. That said, your speakers should be located at roughly 28% of room width, give or take a couple of points. Yours seem to be much closer to the center than that.Moving the speakers farther apart will require myself to move back to maintain an equilateral triangle.
Yes.1: Considering the close distance of the speakers to the LCD (and corresponding flat front wall), am I disturbing the "infinite baffle" too early to fully benefit from it?
Right. There's a reason for that... :)Most designs I see have a window in the location of my LCD (a depression rather than outward projection) and speakers placed farther outward in the baffle.
Why is that a requirement? :) In reality, it isn't Here too the "Speaker position cops" will not drag you off to jail if you move your speakers further apart and angle them better...Given my requirement to NOT move the speakers outwards,
Yes: it works great! I have done soffit-mounted Adams for a few clients, and they are happy. Mostly A7 and A7X, though, which are harder to do, due to the beveled front baffle. Adams are pretty good speakers, and they soffit mount well.3: Does anybody have real-world experience with flush mounting active Adams?
Any soffit-mounted speaker needs cooling. That's an important part of the soffit design; you msut ensure that you get good airflow past the rear surface of the speaker, to keep it cool.though they are relatively warm-running
True, but any good carpenter should be able to cut the soffit baffle to fit.I recall reading somewhere that the beveled front edges make proper flush mounting difficult
Perhaps because you are imposing unrealistic limitations that aren't necessary? :)I'm starting to think that a true RFZ splay with flush mounts can't be achieved with my limitations?
You seem to be confusing "listening position" with "axis intersect".... It's a common issue. The idea is to get your ears about the same distance from each speaker as the speakers are apart form each other. But since your ears poke out the side of your head (rather then being located inside your eyeballs, or on the tip of your nose), then you need to slide your chair forwards a bit to get your EARS on the acoustic axes of your speakers. That means that your head is now further forward than the traditional (but incorrect) notion of the equilateral triangle, so you need either change the speaker angle, or move them further apart, or both.... In fact, many engineers prefer to be a bit closer to the speakers than conventional "equilateral triangle" wisdom allows for.speakers placed to the side are naturally 6 ft apart. At 30 degree angles the listening position is indeed 6 ft
This might sound a little harsh, but it does seem like you are prioritizing your nice screen over the acoustics of the studio. That doesn't seem like a good way of approaching a studio design. First and foremost it is a STUDIO, meant for critical listening of audio material. There are specifications that describe exactly how that should sound (ITU, EBU, AES, and several others), in terms of frequency response, decay response, etc. If you don't want to design the room to meet those specs simply because you happen to like having a very large screen up front, then you can't really expect the acoustics to be much good, so you are sort of defeating the entire purpose of building a studio in the first place! Studio design is a large set of compromises, with each decision being taken to get the room sounding as good as it possibly can, and other aspects taking second place. That's the goal for studio design: get it as close as possible to the specifications. If you deliberately ignore the specifications in favor of having a nice video screen, then you are not building a studio! It isn't a critical listening room any more: it becomes a critical viewing room, where acoustics takes second place. In my book, that isn't a studio: its a room for looking at a nice monitor, and it happens to have some speakers in it too, for listening to mediocre sound. Personally, I would not like to mix in such a room. My mixes would not translate well, since the room would not be telling me the truth.I do understand, of course, that switching to 1080p would allow me to sit much further back. But... its just not gonna happen. I am a power user when it comes to computers ("massive geek" sound better?), and with regard to studio specifics I tend to use high track counts, lots of plugins, lots of soft synths, use RME TotalMix extensively, edit heavily, work with MIDI constantly, etc etc. That, and I deplore scrolling and window juggling. All told I am screen-real-estate junkie. In fact, my actual design has TWO 4K screens - the other being mounted above and with an angle. I removed the second screen for the sake of simplifying my current questions. =)
Correct. The minimum baffle size depends on the low frequency response of the specific speakers you intend to use, but basically you want as much surface as possible all around the speaker, but with different area on each side, to avoid focusing the sound ("beaming"), and also to minimize SBIR artifacts from the surrounding surfaces. - Stuart -It seems that there would be a minimum necessary mass on all 4 sides of the speaker in order to achieve the "infinite baffle" effect?
Soundman2020 your timing is actually perfect. I've been out of state working and unable to participate here. Thank you so much for your contributions to this and the countless other threads. And thanks FriFlo, I was finally able to read your suggested thread and mull over your suggestions. Now... on with my reply!
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So, before we continue to the math and layout fun, lets chat about the 4K screen.
I am pretty sure you will get eye fatigue faster with this distance
sounds more like you really want this screen and talk yourself into that it is going to work.
I can feel the collective cringes and I completely understand that its bordering on sacrilege to make design decisions around a computer monitor. =] Before I proceed let me make it clear that nothing is set in stone, and however foolish I may be I'm not a complete fool. I'm certainly not willing to design a horrible room for the sake of a monitor. I am, however, definitely willing to make compromises if any reasonable ones exist. Please trust that I'm listening *very* keenly to your informed objections. So, I apologize that I didn't include more information initially... it should perhaps have been mentioned that 80% of the work done in this studio will be for myself. My writing / editing / mixing / rewriting / etc tends to blur into one interconnected process. Within that, I do alot of MIDI programming and interact heavily with the software in general. Thus the design ultimately needs to feel right for how I like to create - its a workflow issue. An analogy some folks might appreciate relates to the whole right brain / left brain thing. Part of the enjoyment of the hardware experience is that the knob is always there. Turn around and you know exactly where to reach for your 1176 output level. Your console phase switches aren't going anywhere. You can stay in the creative zone because of the spatial and muscle memory that environment fosters. I suppose I'm on a bit of a mission to recreate that "spatial consistency" in the software world. Futzing about with menus, scrolling around and moving windows is rather antithetical to that. I want to look forward and see my whole "studio", the same as one might see their whole console. Interacting with projects on a 4K monitor has been the closest I have come to that idealization - and frankly I still feel giddy when I load a session and see 70 tracks side by side.The original screengrab: I searched high and low for a solution that would grant this much real-estate, and while there are alternatives the 4K screen won by a landslide based on several factors. Alternatives: - Grid of four 1080p monitors. Not as cost efficient per pixel, but a good solution. Unfortunately you're always looking at the seams, especially the vertical centerline. DAW elements will span across the seams in awkward fashion. A grid of six monitors solves the centerline debacle, but now you'll have twice as many spanning seam issues. - Bank of four 1080p projectors in an actively cooled whisper box, displaying on an acoustically transparent screen in front of the speakers. GREAT solution, and my preferred. Software is readily available that will stitch the projections together into a perfectly seamless whole, accounting for skew / edge blending / etc. Unfortunately the price per pixel is still much higher for projectors and you'll be buying expensive bulbs every year. LED instead? Astronomically higher price. It is my hope that solid state projection technology matures quickly (it uses phase shifting of light!): http://www.caltech.edu/content/bending-light-tiny-chip Otherwise, Seiki is releasing its pro line of 4K/60hz/HDMI2 screens in the coming months, which will include a 65" and 85" model. Unfortunately the 85" will still carry an extreme, early adopter price tag. The 65" panel is a relatively affordable option and it would add about 1 foot to the optimal viewing distance, if that helps solve my dilemna. I suppose, at the opposite end of the scale, one could choose a 39" 4K monitor and place that closer... similar to the dual 22" 1080p setups that seem so common. lol. I'm obsessed. I've got lots of drawing and redrawing to do. ------------- Lets get back to the room generalities!This might sound a little harsh, but it does seem like you are prioritizing your nice screen over the acoustics of the studio.
I would take a look at Johns designs for angles greater than 60 degree.
I had read about John's 90 degree setups but shied away as I was scared of having an exaggerated stereo field. That, and I didn't know if I liked the idea of the couch position being so heavily off axis... both for stereo imaging and the high frequency roll off. Upon reexamination it appears larger angles really are my only option, if I am to stay the 4K course.so then forget the "equilateral " part! I promise, you won't be arrested by the triangle police! :) You can angle your speakers at a higher or lower angle, within reason. You can go down to about 25° and up to about 45° if you have to. As long as you realize that you will be changing the shape of the sweet spot, and allow for that, you'll be fine.
Roger that, thanks! I recently noticed that guideline in another thread you commented on.Ideally, the speaker should be about centered at about 2/5 of the width of the infinite baffle.
Got it.You also do not need to angle the rear part of the wall, behind the mix position. That just wastes space. That section can be flat.
Copy that.That said, your speakers should be located at roughly 28% of room width, give or take a couple of points. Yours seem to be much closer to the center than that.
Wow. Great catch. That was a combination of lapsed attention and geometric ignorance. I feel foolish. =] Somewhere in the excitement of sketching things out I think I got backwards and inside out with the whole 16" behind the head bit. That and I neglected to measure the actual speaker to ear distance (4' 6", yikes!) and didn't even notice the ears are completely off axis. :oops: What a mess!You seem to be confusing "listening position" with "axis intersect"
I found your post with the "quarter-wavelength" guideline for that. Thanks! ------------ Unfortunately I'm out of time for the evening, but tomorrow I will throw together multiple sketch variations and see if I can't come up with something that works. I have one actual question for this post... and its embarrassing.... but: 1) In looking at all of the different soffit designs in various levels of sketchup completion, I still haven't been able to discern if the soffit BECOMES the new inner leaf, or if its just an addition in FRONT of the inner leaf. Several drawings portray it differently. I haven't been able to deduce it from context clues because: A) If the soffit face IS the inner leaf, wouldn't the large gap at the bottom (John's design) destroy the MAM properties and thus the wall's isolation value? B) If the soffit is an addition in FRONT of the inner leaf, wouldn't the soffit face become a third leaf? Thanks infinitely. Your assistance is so greatly appreciated and has already helped nudge me towards solutions.The minimum baffle size depends on the low frequency response of the specific speakers you intend to use
As one of my teachers used to say, many years ago: "The only dumb question is the one you DON'T ask!". You actually raise a very good point, and I think it is confusing to many people, so I'll try to clarify a bit (and probably "mudify" a bit too...). Yes, technically the front face of the soffit (the "baffle") does become the new inner-surface of the room, since it is the hard, solid, massive, reflective barrier that sound waves "see" as they bounce around the room. So that's what you should use for your dimensions, modal response calculations, etc. However: you still need another wall behind it, to contain the sound leaving the rear of the speakers (there's plenty of it!). So there is also a wall back there, that appears to be another leaf. Very true: it is also hard, solid, massive, reflective, etc. So therefor, yes, technically the soffit does also constitute that dreaded monster called "third leaf". :shock: :!: :cry: . BUT! There's a caveat in there: it is a third leaf, undoubtedly, but the resonant frequencies are tuned so low as to make it not really an issue (assuming that both the wall and the soffit are built correctly). The depth of the cavity inside the soffit is very large as compared to the depth in a typical 2-leaf wall (after all, the speakers have to fit inside that cavity, and you also need ventilation space), and the front baffle has to be very massive and rigid anyway (that's just the nature of soffit baffles), so the MSMSM resonance is way down low, and therefor should not be an issue.I have one actual question for this post... and its embarrassing.... but: 1) In looking at all of the different soffit designs in various levels of sketchup completion, I still haven't been able to discern if the soffit BECOMES the new inner leaf, or if its just an addition in FRONT of the inner leaf. Several drawings portray it differently. I haven't been able to deduce it from context clues because: A) If the soffit face IS the inner leaf, wouldn't the large gap at the bottom (John's design) destroy the MAM properties and thus the wall's isolation value? B) If the soffit is an addition in FRONT of the inner leaf, wouldn't the soffit face become a third leaf?
Yes no not really maybe but negative... ! :) First, it is important to recognize that you do not need to have the cavities sealed air-tight in order to have a 3-leaf system: simply having three pieces of large flat massive panels arranged with two air gaps is enough to create a resonant system. It won't be an highly effective resonant system, but it will still be one. If you cut large holes in the shell of a kick drum, it will still resonate, just less than when it was complete. And of course, if you cut a hole in one of the heads of a kick drum, it will also still resonate, just less than before. So you don't need a sealed system in order to have a resonant system, either 2-leaf or 3-leaf. Sealing just makes it a lot more efficient. So assuming that you built your entire room correctly, you have a two-leaf wall that defines the room, then you put up a third leaf which is the soffit baffle, and that does make it a third leaf. but you also have that hole at the bottom, plus the ventilation holes, so it isn't a sealed system, and therefore is not a very effective 3-leaf system. Plus, it is tuned way down low, so the small effect that it does have, just isn't an issue. I hope that didn't totally confuse you, because reading it over again, it sure confused me, and I just wrote it! :) - Stuart -A) If the soffit face IS the inner leaf, wouldn't the large gap at the bottom (John's design) destroy the MAM properties and thus the wall's isolation value?
Actually Stuart, that last paragraph put it all together crystal clear. Considering the large air gap, coupled with the missing sections of mass it is a weak and thus ignorable (for practical purposes) third leaf. Great explanation. I now recall a thead post of yours discussing air cavity depths at which point the third leaf can effectively be ignored (for adjacent hallways, storage, etc). You went deeper into the resonance math of the entire 3-leaf system there. Though I haven't memorized the equations I do recall air gaps of multiple feet approaching a practical level of "ignorable." So, its all making perfect sense. Thanks! ------------- I managed to try out some sketch ideas before I went comatose last night. Initial results aren't incredibly promising. While experimenting with a 90 degree system I realized the limitation of room width. To maintain a distance of roughly 6.5 ft from speaker to ear, with speakers located 25-28% of the room width and at 45 degree angles.... the room must be approximately 18.5 ft wide. I'm not bound by room dimensions at this moment, but that is far wider than I want for a control room (which will invariably force me to build more length than wanted. There is the option to work sideways, but the listening position will end up near the center of the room. It would also significantly raise the the frequency of primary front-to-back modes. Awful idea! I see Vizio will be entering the 4K market this year, and is offering a somewhat affordable 70" panel for around $2700. With the competition prices should drop pretty dramatically in short time. So, I'm kicking around an idea here: Design the room around a larger (future) panel, and mount my 55" panels on a rolling track. That way I can keep the panels closer when writing/editing/premixing etc... and then roll them back and PERHAPS :wink: switch to a lower resolution for pure mixing. All this talk of 1080p at a distance, but I've neglected to mention that 55" @ 2560x1600 is quite visible from afar, and would be my compromise in this case. That leaves me with one question. 1) Is there a guideline acceptable level of off-axis sound obstruction? Pehaps defined by the obstruction's distance from the speaker and its degrees-off-axis? Consider you are sitting in the sweet spot and the speakers are clearly visible. The panel is blocking perhaps all of the sound coming 25 degrees off-axis from either speaker. I assume the high frequencies, being very directional, will be ignorably affected. Obviously as we approach the low mids and below we are dealing with masses of sound hitting the back of the panel. But the on-axis low freqencies are still making a clear path to the ears. So, am I too assume that the only real effects will be A) A shrinking of the sweet spot. The listener moves too far to one side and the panel blocks the direct sound. - and - B) A significant backscattering of off-axis mid and low frequency information. As the less directional sounds hit the panel they bounce back towards the front wall. If these are the only real effects it seems like they could be easily managed (if you are OK with a narrow sweet spot... which I am). The panel could have plenty of trapping added to the back and the front wall is assumed to be properly treated as per RFZ standards. If the first panel reflections into the RFZ result in secondary reflections that are destined for the listener, a wooden facade could be fitted to the panel's rear which redirect those reflections to somewhere more agreeable. I picture a semi-circle. Or a 2D diffusor... to send it back into the RFZ with much less focused energy? lol... ok, now I'm just making things up. When I get home tonight I'll get to raytracing and see what kind of disaster I'm in for.So assuming that you built your entire room correctly, you have a two-leaf wall that defines the room, then you put up a third leaf which is the soffit baffle, and that does make it a third leaf. but you also have that hole at the bottom, plus the ventilation holes, so it isn't a sealed system, and therefore is not a very effective 3-leaf system. Plus, it is tuned way down low, so the small effect that it does have, just isn't an issue.
You are worried about your width. You can use a sawtooth shaped wall to still get your angles for your rfz. Take a look at this post for an idea of what I am talking about. viewtopic.php?f=2&t=16887
The discussion starts about 2/3rd of the way down the page.
What I did, was take the shape of an RFZ room, and move the last angle directly over, but leaving a gap where the sawtooth is and filling it with rockwool to absorb all of those reflections. Everything else should be sent to the giant absorber on the back wall. The jury is still out on whether this will work, but I haven't been able to come up with any reason why it won't work, and no one has come up with any legitimate reasons why it won't. The room is framed but at the rate that I work, it probably won't be finished for a while to truly test out.Here is a more accurate drawing.External image, not preserved — original: http://dl.dropbox.com/u/1049914/control%20room%20rays.pngExternal image, not preserved — original: http://dl.dropbox.com/u/1049914/control%20room%20detail.png
Hi Eric, thanks for the reply!
I read your entire thread, and the CID/sawtooth stuff is interesting for sure. But, I have to say... I'm not sure how that applies here? I'm not running into any issues with width other than not wanting to build wider to support larger speaker angles whilst keeping the speakers in the 25-28% of width region. Thats not something the sawtooth helps with. Unless I completely misunderstood... and then please enlighten me! =]
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That brings me to two more questions I have.
1) I have seen it mentioned in multiple threads that the walls do not need to be angled behind the mix position. But I feel like I've seen multiple designs that do incorporate this (aren't some of John's?, MHOA page 363 - thats where I got my basic RFZ layout). That's a little confusing, surely, but I think I get the point that it won't make a difference at the mix position. However, one thing I wondered about is the couch listening position. As this is located near the rear of the room, wouldn't parallel walls here encourage flutter and stronger axial modes to the guests? Or is that not applicable given that the sound source is coming from a distant location that is nearly perpendicular (in a general, directional sense) to the couch walls?
2) In multiple threads I have seen the suggestion that the speakers be placed 25-31% of the room width... but I haven't come across that in any articles. I'm just curious, is there any specific reason for those numbers? I just assume it is a mix of practicality and acoustics. I understand that stand-mounted speakers in a corner would be radiating in quarter space and have the resulting low frequency boost... but surely that doesn't apply to soffit mounted speakers as well? My memory seems to think its seen multiple builds with the soffits straddling the corners. Just looking for some theory behind the guideline. =]
ewb,
I saw you say how you were worried about how changing the baffle for the speakers would make the room too wide
If you did what I was talking about, you could increase the size of the baffle without increasing the width of the room and still get an RFZ effect. If you want to upload your sketch up file, I can show you exactly what I mean.While experimenting with a 90 degree system I realized the limitation of room width. To maintain a distance of roughly 6.5 ft from speaker to ear, with speakers located 25-28% of the room width and at 45 degree angles.... the room must be approximately 18.5 ft wide.
What you can do there is put some strategically located absorbers. It is a more efficient use of space. The angles from the speakers are much larger and wouldn't have much of an effect on non critical listening. What are your plans for the back wall and ceiling of the room?) I have seen it mentioned in multiple threads that the walls do not need to be angled behind the mix position. But I feel like I've seen multiple designs that do incorporate this (aren't some of John's?, MHOA page 363 - thats where I got my basic RFZ layout). That's a little confusing, surely, but I think I get the point that it won't make a difference at the mix position. However, one thing I wondered about is the couch listening position. As this is located near the rear of the room, wouldn't parallel walls here encourage flutter and stronger axial modes to the guests? Or is that not applicable given that the sound source is coming from a distant location that is nearly perpendicular (in a general, directional sense) to the couch walls?
Adding to what Eric said: If you play around with Thomas Barefoot's "Wall Bounce Calculator" (the 2D version, not the original 1D version), and Jeff Bagby's "Diffraction and Boundary Simulator", and also "The Edge Speaker Baffle Step Calculator", you'll get a pretty good idea of how speakers interact with the walls around them, and you should be able to see where that "21% to 31%" recommendation comes from. Closer to the side walls than about 20%, and you get unacceptable SBIR and other issues, and if you have them more than about 1/3 of room width away from the walls, that puts the speakers too close together in most typical home studios, as well as creating too much interaction between them, and needing to reduce the toe-in angle too much. Of course, those recommendations are for typical home studios, since that's what the forum is mostly about: It is possible to use other locations for speakers if the room is large enough, or if special design issues are involved: For example, many professional studio control rooms are large enough that the layout can be turned "sideways", with the speakers firing along the shorter axis, because that "shorter axis" is still plenty long enough to avoid the issues related to the Hass effect, and that makes it possible to have the side walls so far apart that first reflections also become a non-issue, speakers can be spaced differently, angled differently, numeric-based diffusers can be used, modal support goes way down low, etc. Large rooms make the designer's job a bit easier, in many ways, and a lot of the "rules" can be relaxed. Those "rules" are much more useful in the typical small rooms which are what most home studio builders have space for. Most home studios go in garages, basements, or bedrooms, and those small rooms create all sorts of restrictions, acoustically. That's what the "rules" are designed for: they give you the best trade-offs under most circumstances. If you aren't restricted to a small room, then you can indeed ignore some of those rules, if you understand the other effects it will have, and how to deal with those. - Stuart -2) In multiple threads I have seen the suggestion that the speakers be placed 25-31% of the room width... but I haven't come across that in any articles.
Morning Eric!
I think maybe we're miscommunicating? I'm not particularly concerned about the baffle sizes or related RFZ outcomes at this point (I haven't gotten that far). =] My qualm was this: I went back to my original, stand-mounted rectangular layout to quickly play around with speaker placement (baffle-free and RFZ-free). I attempted a wider speaker spacing with larger (90 degree) angles to gain ear-to-speaker distance while keeping the LCD panel near to my face. I noticed that as the speaker spacing approached what I required, the speakers themselves were getting extremely close to the side walls. The consequence (to my understanding) is that the room would need to expand in width to reach my target ear-to-speaker distance (6.5 ft in this case) if attempting to reach that target via speaker width + angle manipulation. Make sense? If I'm somehow still misinterpreting what you mean then I'd be happy to upload my sketch. Its currently in shambles though, as I've been hacking and slashing all night while reading / experimenting. And, funny enough, I designed my sketch accurate to 1/32 of an inch from my initial ratio calculations. I hadn't thought to round off and use real-world numbers... and wow are some of the distance-between-items calculations hilariously / arduously fractional. I was actually just about to scoot over 25 feet and start from scratch. =]I saw you say how you were worried about how changing the baffle for the speakers would make the room too wide
Roger that, thanks. I had assumed that would be the answer, despite its simplicity.What you can do there is put some strategically located absorbers. It is a more efficient use of space. The angles from the speakers are much larger and wouldn't have much of an effect on non critical listening.
Haven't meditated too deeply on that yet. This whole "Massive LCD Dilemna" really stopped me in my tracks. =] That being said... I'll be doing the rest of the design all pretty standard. Pretty sure I'll end up finishing the RFZ in the vertical direction (slant towards the ceiling) and then using a hanging ceiling cloud for the whole room and ceiling tiles above (as per Build it Like the Pros). I had considered splaying the ceiling all the way to the rear, but I'm starting to think that would be overkill? I also don't entirely understand how one frames a slanted roof at this point, so its something I'm hiding from at the moment. I have a background in fine wood working (not construction)... so I know how *I* would frame it, and it would be gorgeous and functional, but that's doubtfully correct or code compliant. Unfortunately the framing book I bought is kind of a dud, and really didn't have any in depth discussions on acute / obtuse angles in plates, studs or joists. =\ Anyhow, the rear wall will just be standard stuff as well. Likely superchunks in the corners, some wall absorption, possibly diffusion. I'm planning to extend the length of the room 2 or 3 feet to get the 1st mode below 30hz. I swear I read a name for that "critical length" somewhere... but I can't seem to dig it up. I want to say it was a person's name... I've been trying to make my way through MHOA before I make too many more design decisions (and speed read Build it Like the Pros a second time)... but honestly I'm having a hard time sitting down with it for extended periods. The content is awesome, but the writing is perhaps less "exciting" than Rod's? But I degress. My first order of business is to design my mix position to accommodate my unique needs... I think everything will fall into place much easier after that.What are your plans for the back wall and ceiling of the room?
Morning Stuart. You snuck one in on me whilst I was replying to Eric.
Ok, great. I figured it was based on some collection of differing attributes that have a "sweet spot" in a sense. I hadn't seen recommendations as low as 21%. If that's the case then I may be closer to victory than I'd thought. My alarm was stemming from having the acoustic axis around 19% of the room width. I don't need to make the room much larger to push that number closer to 22-23% (and I was considering making the room slightly larger anyhow). I'm not physically limited by room dimensions as I have yet to settle on a site location, but ultimately I am aiming for a 1200-1600 sqft warehouse build. That will consist of control, tracking, vox iso and perhaps one instrument iso. So, I'm always bearing that overall picture in mind whilst playing with the room layout. Perhaps I'm doing things backwards, but I'm aiming to finish my "idealized" rough draft before committing to a location. I realize there may likely need to be myriad compromises at that point... but I'll be far better prepared and able to modify layouts in short order. Thanks as always for your input! I'm 10 minutes away from starting my fresh sketch and seeing if me and Mr. 4K can't somehow coexist peacefully.if you play around with Thomas Barefoot's "Wall Bounce Calculator" (the 2D version, not the original 1D version), and Jeff Bagby's "Diffraction and Boundary Simulator", and also "The Edge Speaker Baffle Step Calculator", you'll get a pretty good idea of how speakers interact with the walls around them, and you should be able to see where that "21% to 31%" recommendation comes from.
Wow... my first "Page 2" on the forum.
The first of many, no doubt.
:yahoo:
A larger room is pretty much always a better room, and if you can get the dimensions within EBU and/or ITU specs, then you stand a really good chance of having a great room. However, be careful with those "rules": that's why I put them in quotes. They are not hard-and-fast laws of the universe, that are carved in stone. Every room is different, and what might work out fine for one room at 21% might be terrible for another room, which really needed 30% (or whatever). The same applies to the "38% rule", and also to the famous "golden room ratio" (even though there isn't any such thing in real life...) All of these rules are just starting points, to get you in the general ball-park of where you need to be, so you can then refine that as needed by your specific room. Ratios are good in the sense that you should get away form the really bad ones and get close to some of the good ones. 38% is good in that it gets you roughly where your ears should be, and 28% is good in the sense that it gets your speakers roughly where they should be. But in all three cases (and also for most of the other "rules") you'll very likely end up with a different final set of numbers, as you adapt and improve your design, working from those points as the basis. In other words, don't assume that 20% is really lousy while 21% is perfect. Instead, if you really want your room to be as best it can be, then take the time to check the locations, plug the numbers into the calculators, look at the graphs, play with them, and see if you can find an even better spot, even if it means changing speaker angles, or the speakers themselves, or room dimensions, or whatever else. Studio design involves probably hundreds of variables that you can change, and many of them depend on each other in some fashion, so it can take a long time to work through all of the possibilities, trade-offs, compromises, etc. I often find that when I'm very well along with the design for a room, I suddenly notice something that can be improved, or that isn't the way I thought it was, or that cannot be done the way I wanted due to some type of restriction, and that leads me to make a drastic change. So I go back to square one and start all over. Sometimes I end up doing that two or three times.... - Stuart -I don't need to make the room much larger to push that number closer to 22-23% (and I was considering making the room slightly larger anyhow).