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Author Topic: Baffle wall question Steven Smith Film Handler Posts: 35 From: Boyce, La/ USA Registered: Jul 2014 posted 06-16-2015 09:43 PM                     You're the man Mark.... Thanks! The stage is going to be 12" tall and the subs be one in each of the four corners. Two behind the screen and two in alcoves in the back corner. I have them labeled on my plans in my link above . Being the subs are in the corners and 6'tall. Can I just frame around them and make their baffle even with the baffle wall? If so I'm guessing I should run the acoustic material across the sub baffles as well.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 06-17-2015 01:11 PM                     Humm, not sure about doing that with the subs. While it may be perfectly ok it is not where THX would locate them. In the systems I have done they are always front and center about 12" above floor. Placing the subs next to each other nets you ~1.5 db more output per pair of subs. So you may want to reconsider that as grouping the four subs together may improve efficiency by as much as 3db. Mark  |  IP: Logged Steven Smith Film Handler Posts: 35 From: Boyce, La/ USA Registered: Jul 2014 posted 06-17-2015 01:32 PM                     I did a ton of research on multiple subs as I'm building alcoves I can't really move them after I install them, so I'm kinda trusting the studies done by others. I linked a study done by Harmon for multiples complete with responses and comparisons. It may not be the best spot but for rooms as small as mine it looks to be a good spot with a smooth response and room gain. If you look two subs at wall midpoints also gives a smooth response which would be similar to what you described. The corner option can also give as much as 6db gain per sub..of course that's optimal. But no matter what I'll have plenty of headroom well above reference. I'll also be using an EQ on them and getting the phase tweaked and aligned with the mains. http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/multsubs.pdf  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 06-17-2015 10:08 PM                     One thing that concerns me placing them in the corners is standing waves. Mark  |  IP: Logged Steven Smith Film Handler Posts: 35 From: Boyce, La/ USA Registered: Jul 2014 posted 07-13-2015 03:50 PM                     Hey guys. So I have my Baffle wall built and treated with 1". My screen will be built with 1x4s and covered with acoustic screen and will hange against the wall using french cleats. Can I mount the screen directly to the baffle wall? I have two vertical braces between the main and L/R speakers. With these 1x4s cause any issues if they are mounted against the baffle wall acoustic material? Here's pics in case anyone wants to see what I'm working with. [ 07-13-2015, 04:32 PM: Message edited by: Brad Miller ]  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 07-13-2015 04:33 PM                     Steven, your link was removed because it breaks the archive. Please upload any pictures relevant to the discussion directly into this thread. When you go to make a new post, there is a text link "click here to upload an image" that you may use. (An example is how Mark G posted his pictures on page 1. This way they are there forever for future people reading this thread.) Please also upload your drawing from your page 1 link. Thanks.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 07-13-2015 05:24 PM                     Typically the screen frame is not mounted to the baffle wall in any way, although a brace here and there may penetrate the wall to connect it to the back wall of the building. Angle iron and springs are the best frame material and best way of hanging a screen. This way the frame is more minimalist and it won't bend or sag over time. The springs allow the screen to breathe with temperature changes maintaining a more constant tension... Mark  |  IP: Logged Steven Smith Film Handler Posts: 35 From: Boyce, La/ USA Registered: Jul 2014 posted 07-13-2015 08:27 PM                     OK, thanks I will try to upload a pic when I get to a pc. As for the frame I've built half a dozen and I have a method that results in a very solid frame and the way I mount it sagging is almost impossible. My question is acoustic in nature. Will it hurt to have vertical pieces of 1x4 centered between the center and mains and to the outsides of the mains against the baffle wall or should they float in front of the baffle and it touch it.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 07-14-2015 03:25 PM                     Hello Steven, Thanks for the JBL doc, very interesting. I found that the hard way in my small home theatre; it's nice to have more literature on the matter.  |  IP: Logged Steven Smith Film Handler Posts: 35 From: Boyce, La/ USA Registered: Jul 2014 posted 07-15-2015 06:37 AM                     Thanks, I'm glad I could contribute something useful! Here's some pics of the room. I just finished covering my panels. My phone is horrible in low light. And here's the baffle wall. Double layers of sheetrock covered with 1" ductboard. So mounting the screen..Any issues with securing the frame to the baffle wall? Should I space it off the wall a few inches? If so how much? I've put a lot of work into the room acoustically and don't want to make any big errors.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 07-15-2015 12:48 PM                     Wow. And... Wow! The screen should be pretty close to the screen but you want to leave a little space or you will see the LF 'soundwaves' from the stage speakers. I'd say 3 inches? You have a sound wall so it shouldn't really matter too much, HF are going to be absorbed by the rockwool.  |  IP: Logged Steven Smith Film Handler Posts: 35 From: Boyce, La/ USA Registered: Jul 2014 posted 07-15-2015 01:19 PM                     So I guess I get your seal of approval?? 3" isn't too bad. I'll just block it off the baffle wall and kind float it then. I may try 2" and measure. I want to keep as much of that edge on the top of the stage visible. I'm also going to throw some 1" ductboard over the sub baffles to continue the baffle wall to the side walls. Yes I did that professional mess of a plan myself.  |  IP: Logged Gerald Dente Film Handler Posts: 14 From: southborough MA usa Registered: Jun 2015 posted 07-16-2015 07:31 AM                     Room is looking great. 2" kinda close to the screen? I was told 3-4" minimum if I was to have subs behind it. Do your subs left and right go behind the screen as well or is it just the QSC's?  |  IP: Logged Steven Smith Film Handler Posts: 35 From: Boyce, La/ USA Registered: Jul 2014 posted 07-16-2015 09:10 AM                     The good thing is I can measure with and without the screen and adjust the distance even after the build is done. Quick and easy. Without measurements it's all speculation anyway as any issue that could exist may not be audible or measurable. The baffle wall is 12' wide the screen is just a tad wider.. (170" diagonal 16:9). The screen will extend over past the edge of the subs but not so far that it's to the cones. The father I pull the screen from the wall the more the side bracing of the screen will get into the path of the mains. I'll hang the projector and screen this weekend and I'll post some pics.  |  IP: Logged Gerald Dente Film Handler Posts: 14 From: southborough MA usa Registered: Jun 2015 posted 07-16-2015 11:14 AM                     Good luck, I always hated mounting my projector. Although I kinda did it backwards and put the screen up first then the projector second.  |  IP: Logged

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