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Discussion Starter · #1 ·
Hey guys, I normally hang out in the DIY section, and have built several speakers & subs, but now that my wife & I are moving into a new home, I finally have the option of building a dedicated theater room! With that being said, I need some help with designing & building a baffle wall in my new, dedicated theater room! Hoping you guys can help answers some initial questions, and hold my hand along the way!


(Note: room is 14' by 17' by 8'. Will have 2 rows of seating, 3 in front 2 in back mounted on a riser with a currently unknown projector & screen. High efficiency DIY Seos-LCR's)


My questions regarding the baffle wall are:


First, what size lumber should I use to construct the frame? Are 2" by 4" studs ok, or should I shoot for 2" by 6" studs for added ridged- ness?


Next, shoyld I place the LCR's on a shelf within the baffle wall, making sure that they end up flush with the surface, and then frame around them with the studs?


Then would it be best to put OSB/plywood over the frame to cover all of the frame network up, or should I use fabric to cover the frame?


I know that it is best to have the speakers come up to flush with the finished walls surface with no overhang, but, I would also like to possibly add some 3" or 6" Safe-n-Sound to the entire front wall. So with that in mind, how should I go about placing and mounting the absorbing material and LCR speakers so that everything comes out flush?


Also, note that I am seriously considering doing an IB sub array behind the screen. I am not sure if that would require any changes to the design, or construction of the baffle wall. If I do end up doing an IB sub built into the baffle wall, would this change the way that the frame needs to be built? (ie: should it be built worth a larger frame?)


Any help, and/or suggestions that you guys can provide would be much appreciated! I thank you guys for reading this!
 

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Discussion Starter · #2 ·
I need some advise on how to construct a baffle wall!


Would it be best to use 2 by 4's to build a frame with the LCR's mounted within? What would be the ideal material to cover the actual frame/skeleton with? Perhaps OSB plywood?
 

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I'm no expert here, so reading and understanding the reference material J_P_A has linked will probably get you farther, but maybe I can point out a thing or two to get you thinking about it critically.


The baffle wall functions to extend down in frequency the transition of the loudspeaker radiation pattern to full space from half space. Getting that transition down below the room's Schroeder frequency should be a goal IMO. The lower frequency transition requires a larger wall (greater distance between acoustic center of low frequency radiation and baffle edge). The bigger the wall, the harder it will be to integrate manifold for an IB sub, unless the baffle wall itself encloses the back wave.


The rigidity and weight of the wall is important, but I don't know what unusual construction is required. It seems to me the only construction I have seen detailed used standard 2x4 spacing, but with three layers of sheething (5/8dw GG 3/4MDF GG 5/8 dw). If you want to increase the rigidity beyond that, I suspect that pairing 2x4 studs in a "T" cross section would be superior to 2x6, but I'm not sure.


Regarding the absorption on the face of the wall, the purpose is to absorb the sound reflected back from the screen so that the comb filter response can be eleminated. This is only a concern above about 10KHz, so thickness is not a serious concern; one inch is probably adequate. I would probably just flush mount the speaker and surround the waveguide about 2 feet in any direction, but that's a hack of a guess. You shouldn't need the thicker absorption that people often need for SBIR control, because the baffle wall provides that functionality and more.
 

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Discussion Starter · #5 ·

Quote:
Originally Posted by J_P_A  /t/1524504/help-with-baffle-wall-construction-design#post_24540293

Section 6.0 of this document discusses Procella's recommendations for baffle wall construction. I haven't read it in a while, so you'd be better off reading it than having me try to paraphrase from memory.

Thanks for the link, that answered many of my questions!


Do you guys think that using 2" by 8" studs in a frame that is covered by two layers of 3/4" MDF and one layer of 5/8" Sheetrock would be sufficient? Or would that be overkill?


Also, it seems that doing an IB subwoofer integrated within the baffle wall may very well be hard to do, but, I am still unclear on that. If I do go with an IB style subwoofer, would it be a good idea to keep the drivers all close together in a line, or could I mount each of my four sub in its own manifold and have each one at the 1/4 distance from the ceiling, floor, and side walls? Should the manifolds themselves also be flush with the baffle wall? Wouldn't the drivers be sticking out from the surface of the baffle wall?
 

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Discussion Starter · #6 ·

Quote:
Originally Posted by Martycool007  /t/1524504/help-with-baffle-wall-construction-design#post_24542942


Thanks for the link, that answered many of my questions!


Do you guys think that using 2" by 8" studs in a frame that is covered by two layers of 3/4" MDF and one layer of 5/8" Sheetrock would be sufficient? Or would that be overkill?


Also, it seems that doing an IB subwoofer integrated within the baffle wall may very well be hard to do, but, I am still unclear on that. If I do go with an IB style subwoofer, would it be a good idea to keep the drivers all close together in a line, or could I mount each of my four sub in its own manifold and have each one at the 1/4 distance from the ceiling, floor, and side walls? Should the manifolds themselves also be flush with the baffle wall? Wouldn't the drivers be sticking out from the surface of the baffle wall?

I am going to be starting on the room very soon, so can anyone tell me if using 2" by 8" studs covered by two layers of 3/4" MDF and one layer of 5/8" drywall would be optimal, or overkill?
 

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Quote:
Originally Posted by Martycool007  /t/1524504/help-with-baffle-wall-construction-design/0_100#post_24543914


I am going to be starting on the room very soon, so can anyone tell me if using 2" by 8" studs covered by two layers of 3/4" MDF and one layer of 5/8" drywall would be optimal, or overkill?

Newb guess here is overkill but don't take my word for it.



Here is some links I accumulated that might help you:


http://www.thx.com/professional/cinema-certification/speaker-layout-and-baffle-wall/

http://www.avsforum.com/t/1456484/baffle-wall-allison-effect-baffle-step-and-half-space-radiation-discussion-calling-acoustic-experts/0_100

http://www.avsforum.com/t/1438775/why-arent-more-screen-walls-filled-with-acoustic-treatment-roxul-oc703-etc/0_100


Old school link:

http://www.avsforum.com/t/1089632/custom-home-cinema/0_100#post_15217675


Very old school link: http://www.avsforum.com/t/433858/baffle-walls/0_100


Another book mark:

http://www.avsforum.com/t/1438775/why-arent-more-screen-walls-filled-with-acoustic-treatment-roxul-oc703-etc/0_100


You are using SEOS speakers ?

http://www.avsforum.com/t/1500707/baffle-wall-with-seos-waveguide-speakers-questions/0_100


And from the DIY audio guys: http://www.avsforum.com/t/1291697/baffle-wall/0_100


The DIY audio guys generally have a higher tendency to try to help and an adventurous spirit. The guys that really know in this forum stay tight lipped until they get your check.


I did also bookmark this one a while back looks like a winner :
http://www.avsforum.com/t/1280395/i-need-help-with-designing-a-baffle-wall/0_100


These links might also help you:

http://www.meyersound.com/products/studioseries/x-10/

http://www.avsforum.com/t/1502737/baffle-wall-with-constant-directivity-waveguide-speakers-and-toe-in/0_100

http://libinst.com/PublicArticles/Setup%20of%20WG%20Speakers.pdf

http://www.dolby.com/uploadedFiles/Assets/US/Doc/Professional/Dolby_Atmos_Specifications.pdf

http://www.avsforum.com/t/894691/thoughts-on-baffle-walls/0_100

http://www.procella.citymax.com/f/Procella_System_Design_&_Installation_v2.5_Web.pdf
 

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2 X 4's , absorption, GOM fabric and plywood.


 

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Discussion Starter · #10 ·
Thanks for the responses guys! I spent most of the evening yesterday reading through those links that Mfusick posted above. Lots of good info in there, but, I have a few questions that I am trying to find the answers to.


It is my understanding that the baffle wall needs to be as stuff & ridged as is possible, right? If so, then my idea of 2" by 8" studs for the frame with two layers of 3/4" MDF with a layer of 5/8" drywall in between the MDF should be sufficient for the actual wall itself!


Does the baffle wall need to be secured where it meets the adjacent side walls & ceiling? Or should the baffle wall be separated or decoupled from the side walls and ceiling, and if so, how should this be


I have read that it is a good practice to use some absorption material on the face of the baffle wall, but, I am unclear on how much would be optimal, or, what kind of absorption material to use? Would 3" or 9" of Safe-n-Sound be sufficient? Would it be better to use something more ridged?


Last question that I can't seem to find an answer to: Should the speaker baffles sit flush with the finished baffle wall including flush with the absorption material used on the outside of the wall? Or should the speakers sit flush to the face of the baffle and have the absorption material stick out more than the speaker?
 

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Discussion Starter · #11 ·
Should the baffle wall be connected to the side walls & ceiling? Or should they be decoupled entirely?


Also, should the area behind the baffle wall be completely sealed up & air tight? I would assume that if using the baffle wall to house an IB subwoofe manifold then it should be air right, but, I have not decided if that is the route I will go wrt subs.
 

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Discussion Starter · #12 ·
Ok, let's try this again, with regards to the baffle wall....


Does it need to be connected to the side walls and ceiling, or should it be decoupled?


How much importance is it to have the area behind the wall be air tight?


Last question...being that the front wall will be 14' wide & 8' tall, how far does the Left & Right speakers need to be from the side walls?
 

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I keep wanting to give you a good answer, but browsing from my phone at work, I can't find the resources. I forget how it's supposed to be: something is supposed to be decoupled from something else, but I can't remember if it's speaker from baffle wall or baffle wall from construction. I think when procella says resilient mounting, the mean the speaker cabinets themselves should be decoupled from the baffle wall, but I'm foggy on that.


The only reason the baffle wall would need to be sealed tightly against the room is if it needs that for subwoofer performance. It functions as a baffle wall without that.


The size and placement of the speakers has to do with a number of things that are application specific. I'd suggest as a rule of thumb, the wall should extend three feet in all directions from the woofer/ports and that position should be established first, emphasizing imaging.
 

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As you have already found, make the wall as rigid as possible. The baffle wall is not decoupled from the rest of the room, however, if you are soundproofing you may want to decouple the wall from the floor joists above depending on the wall's location. You will want to decouple the speakers from the cavity by using floating mounts or some sort of vibration isolator, you will also want to fill the void of the cavity with whatever you're using for sound absorption, maybe some OC 703 or even sand bags. Next you will need to attach a flush bezel to the face of the cavity (your final layer on the wall should have the speaker cavity's rectangle cut out larger than all of the other layers, allowing the bezel to attach flush to the wall), the bezel should have a rubber gasket around it to ensure there is no gap but also maintain vibration isolation from speaker to wall. Also, I'm not sure how this will affect the SEOS speakers, as I understand they are designed to be in room right? I hope this all makes sense and helps you.





-Sean
 

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Discussion Starter · #15 ·
Thanks for the replies to both Fred & Sean! Now that I have the baffle wall's construction and design down, I now have some questions regarding the risers, which hopefully someone can answer for me!


So the plan is to build a two stage riser for two rows of seating. The front & back row will be two seats each. My questions are:


1. How do I determine the optimal distance from the front & rear wall? I have read that the listening position should not be at the exact middle point of the room, nor should it be up against the rear wall. The room will be 17' by 14' by 8'. The projector is still undecided so I will also have to factor that in , but, for now I am more concerned with the audio side of this build.


2. How tall should each section (ie front & rear) be? I want the back row to extend higher than the front, but still maintain a somewhat decent hight so as to not muck up the sound heard from the speakers. The front row will have the most optimized SQ.


3. What should the riser be constructed with? I would assume that it can be done with a 2 by 4 frame or skeleton, then covered with plywood?
 

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Riser size and seat positioning is a juggling act - you've set the priorities properly, IMO, but maybe there's a misunderstanding or two. For two rows of seating, you only need one riser - the front row goes on the floor; there's no need to raise it, it would just get in the way of the second row if you did. (Maybe I've misread your post a little?)


Is the 17' dimension from the room's wall, the baffle wall, or the screen?


It's true especially that bass issues are hardest to manage at the walls, and the middle of the room will have problems. All positions will have problems - the problems in the middle of the room will be mostly isolated to a couple strong resonances at a couple frequencies. Modal bass issues are best dealt with using a three-pronged approach, IMO: 1- Multiple subs (4 is a good number, but three's not bad) spread around the room, 2 - bass trapping, 3 - independant EQ for each sub (delay, phase, and EQ). Assuming you're willing to do these right things, I wouldn't worry too much if the prime seating position comes out at or very near the center of the room, but if it's easy to avoid, I would. Instead, focus on positioning the seat for stereo imaging and surround envelopment.


Once you've positioned the money seat, you can add the second row. If you're using recliners, bank on the second row being 6.5 feet back (ear to ear). With that you know the distances for both rows to the screen and the height of the top of the heads in the front row (that's the visual obstruction the second row needs to clear), so you either fumble through the geometry and a scale drawing, or you use the handy riser height calculator website linked in the sticky at the top of this subforum.
http://calc.xn--f5a.net/ You'll be tweaking the height of the bottom edge of the screen and the height of the riser; they're related like oposite ends of a see-saw, pivoting on the heads of people in the front row.


Now you evaluate the outcome and consider tweaking. Wash, rinse, repeat until you are happy with the compromises. Then you can add the other screen dimensions and projector to your model and do it all again!



Riser construction is simple. You build the edges from 2x lumber and then hang other (usually smaller) 2x lumber on 16" centers inside the frame. Sometimes you will need some kind of support mid-span, sometimes you wont. Then you lay proper subfloor on top of it (3/4" tongue and groove). Usually you'll want two layers of subfloor to make it feel less springy. Layers should be screwed together and often with something between them to inhibit squeaking, like roofing felt or green glue. This thread has a good summary discussion and pictures http://www.avsforum.com/t/1481838/building-a-riser-need-lessons-learned-help-please (Listen to BIGmouthinDC)
 

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My baffle wall is probably one of the larger one's here and it's constructed from 2" x 6" with two layers of 3/4" MDF. The baffle wall is not decoupled from the rest of the room. The speaker baffles are flush with the face of the MDF and the 1" insulation sits proud.


Some photos in my build thread.


Cheers,
 

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Discussion Starter · #18 ·

Quote:
Originally Posted by HopefulFred  /t/1524504/help-with-baffle-wall-construction-design#post_24559311


Riser size and seat positioning is a juggling act - you've set the priorities properly, IMO, but maybe there's a misunderstanding or two. For two rows of seating, you only need one riser - the front row goes on the floor; there's no need to raise it, it would just get in the way of the second row if you did. (Maybe I've misread your post a little?)


Is the 17' dimension from the room's wall, the baffle wall, or the screen?


It's true especially that bass issues are hardest to manage at the walls, and the middle of the room will have problems. All positions will have problems - the problems in the middle of the room will be mostly isolated to a couple strong resonances at a couple frequencies. Modal bass issues are best dealt with using a three-pronged approach, IMO: 1- Multiple subs (4 is a good number, but three's not bad) spread around the room, 2 - bass trapping, 3 - independant EQ for each sub (delay, phase, and EQ). Assuming you're willing to do these right things, I wouldn't worry too much if the prime seating position comes out at or very near the center of the room, but if it's easy to avoid, I would. Instead, focus on positioning the seat for stereo imaging and surround envelopment.


Once you've positioned the money seat, you can add the second row. If you're using recliners, bank on the second row being 6.5 feet back (ear to ear). With that you know the distances for both rows to the screen and the height of the top of the heads in the front row (that's the visual obstruction the second row needs to clear), so you either fumble through the geometry and a scale drawing, or you use the handy riser height calculator website linked in the sticky at the top of this subforum.
http://calc.xn--f5a.net/ You'll be tweaking the height of the bottom edge of the screen and the height of the riser; they're related like oposite ends of a see-saw, pivoting on the heads of people in the front row.


Now you evaluate the outcome and consider tweaking. Wash, rinse, repeat until you are happy with the compromises. Then you can add the other screen dimensions and projector to your model and do it all again!



Riser construction is simple. You build the edges from 2x lumber and then hang other (usually smaller) 2x lumber on 16" centers inside the frame. Sometimes you will need some kind of support mid-span, sometimes you wont. Then you lay proper subfloor on top of it (3/4" tongue and groove). Usually you'll want two layers of subfloor to make it feel less springy. Layers should be screwed together and often with something between them to inhibit squeaking, like roofing felt or green glue. This thread has a good summary discussion and pictures http://www.avsforum.com/t/1481838/building-a-riser-need-lessons-learned-help-please (Listen to BIGmouthinDC)

Thanks for the reply Fred! Much appreciated!
 

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Discussion Starter · #19 ·

Quote:
Originally Posted by HopefulFred  /t/1524504/help-with-baffle-wall-construction-design#post_24559311


Riser size and seat positioning is a juggling act - you've set the priorities properly, IMO, but maybe there's a misunderstanding or two. For two rows of seating, you only need one riser - the front row goes on the floor; there's no need to raise it, it would just get in the way of the second row if you did. (Maybe I've misread your post a little?)


Is the 17' dimension from the room's wall, the baffle wall, or the screen?


It's true especially that bass issues are hardest to manage at the walls, and the middle of the room will have problems. All positions will have problems - the problems in the middle of the room will be mostly isolated to a couple strong resonances at a couple frequencies. Modal bass issues are best dealt with using a three-pronged approach, IMO: 1- Multiple subs (4 is a good number, but three's not bad) spread around the room, 2 - bass trapping, 3 - independant EQ for each sub (delay, phase, and EQ). Assuming you're willing to do these right things, I wouldn't worry too much if the prime seating position comes out at or very near the center of the room, but if it's easy to avoid, I would. Instead, focus on positioning the seat for stereo imaging and surround envelopment.


Once you've positioned the money seat, you can add the second row. If you're using recliners, bank on the second row being 6.5 feet back (ear to ear). With that you know the distances for both rows to the screen and the height of the top of the heads in the front row (that's the visual obstruction the second row needs to clear), so you either fumble through the geometry and a scale drawing, or you use the handy riser height calculator website linked in the sticky at the top of this subforum.
http://calc.xn--f5a.net/ You'll be tweaking the height of the bottom edge of the screen and the height of the riser; they're related like oposite ends of a see-saw, pivoting on the heads of people in the front row.


Now you evaluate the outcome and consider tweaking. Wash, rinse, repeat until you are happy with the compromises. Then you can add the other screen dimensions and projector to your model and do it all again!



Riser construction is simple. You build the edges from 2x lumber and then hang other (usually smaller) 2x lumber on 16" centers inside the frame. Sometimes you will need some kind of support mid-span, sometimes you wont. Then you lay proper subfloor on top of it (3/4" tongue and groove). Usually you'll want two layers of subfloor to make it feel less springy. Layers should be screwed together and often with something between them to inhibit squeaking, like roofing felt or green glue. This thread has a good summary discussion and pictures http://www.avsforum.com/t/1481838/building-a-riser-need-lessons-learned-help-please (Listen to BIGmouthinDC)

I am now debating the whole riser & second row idea altogether. The room is 17ft by 14ft by 8' with the screen on the 14ft wall.


My wish to have a riser was in part because every single wall in the entire house, both exterior & interior are made of concrete. I thought that by using a riser I could get some more "feel" of the bass since I would be sitting on the riser versus concrete. I would like to comfortably seat 3 to. 4 people, max.


Given that, do you think that I could squeeze 3 to 4 seats next to each other instead of a second row without loosing too much off axis SQ? Again, room is 17ft by 14ft by 8ft.


Where is a good place to purchase theater seating that is some what cheap? Thanks for the help guys! I really appreciate it! I plan to start cutting wood next week!
 

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14 feet wide room can accommodate 4 seats wide, but it will be tight. I personally will be buying seats from Roman (who you may find mentioned in this subforum pretty often). His website is http://www.rtheaters.com/ I found that for the name brand seats, like Berkline, or Roman's house line, Fusion, pricing is pretty competitive across the board - though I think Fusion is one of the best values around. The Jive seat is one of the very narrowest designs. A set of four seats with loveseat center |0|00|0| is 109" wide; that leaves an aisle of close to 30" on either side (assuming your room is 14' 0"), which will be very nice. Aisles below 24" are cramped, IMO. 4 seats in standard configuration |0|0|0|0| is 115", leaving 26 or 27" aisles - still great. A wider seat design, like the Lagoon is 9" wider in those configurations - still workable. On the other hand, the Escape is larger still, and really starts to impinge on your aisle space. (Those are all Fusion Collection seats) Call Roman for pricing, he's very easy to deal with.


If you don't want recliners, traditional rockers or other commercial type designs are a good bit more compact, and lower cost - but obviously, you trade features for the size and cost. Google home theater seating, and I imagine you will get several good results. As long as supply and customer service are good, I bet you get very similar results from most of the options.


I imagine that a small riser is practical for the tactile feeling you're describing. The question for me is how much headroom you're willing to give up for it. I would not be, but that's a personal call. IMO, taller ceilings is probably the most often wished for feature in home theaters, but 4 inches or so for a small suspended floor is not a lot. What happens is soffits and projectors come down form the ceiling and start to make the room feel a lot smaller, but again, it's a personal call.
 
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