Stimy Posted January 23, 2006 Share Posted January 23, 2006 I have been working on my decated home theater room for a while now and I am ready to drywall. I just need some advice on a few things while I have the walls open. My room is 16.8 ft long and 13.3. Its not the ideal size but thats all I have to work with. I am planing on installing a 5.1 or 7.1 THX Ultra 2 system . Please look at the pictures and it will give you abetter idea of what Im talking about. I have wired for 7.1 and my subs are in the two front corners (red wires). I have a teir in the back at about 10in high. I am having problems placing my KS-525 in the back. Also I was thinking of using the in-wall Ultras in the back. Any help and advise would be great and if you in the Salt Lake City area any time soon you can come on over!!! I have Photoshoped the pics so its more helpful or not. thanks Sterling Quote Link to comment Share on other sites More sharing options...
ygmn Posted January 23, 2006 Share Posted January 23, 2006 what pic? Quote Link to comment Share on other sites More sharing options...
Stimy Posted January 23, 2006 Author Share Posted January 23, 2006 more pics Quote Link to comment Share on other sites More sharing options...
Stimy Posted January 23, 2006 Author Share Posted January 23, 2006 more Quote Link to comment Share on other sites More sharing options...
Stimy Posted January 23, 2006 Author Share Posted January 23, 2006 one more Quote Link to comment Share on other sites More sharing options...
Chris Robinson Posted January 24, 2006 Share Posted January 24, 2006 Sterling, First, really like your avatar! Secondly, you're on your way to a really killer system and HT. I don't think your dilemmas are major comprimises at all. I'm sure HTExpert or Soundbroker will jump in soon with some really expert suggestions. I'd just be guessing. Quote Link to comment Share on other sites More sharing options...
DrWho Posted January 24, 2006 Share Posted January 24, 2006 Ok, for the subs....you want the hole in the drywall to be just large enough that the drywall isn't touching the sub (but you want the gap as small as possible). And then you'll want to throw in a little absorbtion in the empty cavity so as to reduce cabinet vibrations from being amplified (a strip along the drywall and a panel on the real rear wall should be enough). Just make sure there is no mechanical connection between the sub and the false wall. I'm not sure I quite understand your picture either...Is that "closed in window" on the rear wall? If so, where did it go in your other picture? Or is the second picture what it looks like now that it's closed in? Because of the close placement of the surrounds to the listening position, I think you will have better results going with the KS-525's instead of the inwalls. The reason being they will provide you with a much wider dispersion and better coverage throughout the listening position. They will only stick out 8" so it's not like they take up a lot of room either...If you're really that concerned about taking up space then you could always mount them partially into the wall....just making sure you leave an angled baffle to avoid nasty reflections. (so instead of the inset being 90 degrees perpendicular to the wall, the inset would go in at 45 degrees...thus forcing the opening of the hole to be a bit bigger). I might need to draw a picture for this to make any sense. You would also benefit from angling the surrounds down a bit to point at the listening position (which will allow higher placement of the rears getting them away from the head while also providing better coverage).Are there going to be two rows of seating? One on the back riser section and then a row just in front? If so, you'd be better off putting that side surround forward...like in front of that pillar just above the fireplace...which would also be close to that location you labelled "doesn't line up with other wall")And lastly, where are your mains going to go? It looks as if you're going with an acoustically transparent screen? Quote Link to comment Share on other sites More sharing options...
DrWho Posted January 24, 2006 Share Posted January 24, 2006 I almost forgot.... that last row of seating is going to have quite a few acoustical issues because it's so close to the rear wall (and so far from the main speakers). You would benefit GREATLY by adding some acoustical treatment. Something like a large panel of 4" acoustical foam on the rear wall between the speakers and then a panel on each side between the side surrounds and rear surrounds. You'll probably want to throw some bass traps in the rear corners too. If you take your time and get creative, you might even be able to enhance the looks of the room in the process. Some diffusion along the cieling wouldn't hurt either. Quote Link to comment Share on other sites More sharing options...
Stimy Posted January 24, 2006 Author Share Posted January 24, 2006 WOW!! Thanks for your time to write all those great insights I know it takes a lot of time to keep up on all these forums and with no payback. First of all I have an issue with the front wall I cant flush mount anything into it because it backs up to my stairs coming down. If I were to build a false wall it would eat up my stage and more of my room. One problem I have with placing the surrounds on the wall above the fireplace is it will really compromise the look. I was planning on putting a nice piece of Italian art up there. Its real tough because I want a great looking theater (Neoclassic European) but I also want great sound. In the back of the room pic I photoshoped the window out thats why you see it in some pic and not others. I think I might get some bad reflections off the back wall and the column with the KS-525 behind the fireplace. What if I used the inwall ver. for the surrounds would that help? I was planning on mounting the center channel just below the screen on a sturdy stand. ThanksSterling Quote Link to comment Share on other sites More sharing options...
DrWho Posted January 24, 2006 Share Posted January 24, 2006 Are you saying an inwall speaker above the fireplace? Yes, that would be better than having the 525 further back. Hey, if you got creative you might even be able to get an acoustically transparent version of that painting and then have the speaker firing through it [] Quote Link to comment Share on other sites More sharing options...
Remotia Posted January 25, 2006 Share Posted January 25, 2006 imo, get the subs away from the corners and place them right next to each other center below the screen. This does two things. Helps reduce a potential corner loaded frequency peak but more importantly, it will allow the subwoofers to be in phase throughout the entire room without comprising localization of either side of the room. Quote Link to comment Share on other sites More sharing options...
DrWho Posted January 25, 2006 Share Posted January 25, 2006 When it comes to an even bass response, you want to "activate" as many nodes as possible, not reduce how many are occuring (and corner loading maximizes the number activated). The simple way to explain this is we don't notice "nodes" or "dead" spots at the higher frequencies because the node distribution is very dense. Placing both subs in the center is going to shift (not remove) a set of nodes and double the magnitude of the horizontal nodes. So what we have here are two competing systems: comb-filtering from spacing the array and the complex nodal structure of the room. I suppose if we were real clever, we could try to take advantage of the comb-filtering effect to help out with the nodal response - but it's only going to help at a select few frequencies. We also have the effect of boundary cancellation as we move a speaker away from the wall (where the reflection off the wall is 180 degrees out of phase with the direct sound). So there's another factor we have to take into account. I'm on a school computer at the moment, but I would like to defer to some research that has already taken all of the factors into account. I'm sure someone will post it - if not, I'll go see if I can find the website. Anyways, someone sat down to a computer to figure out the optimum number and location of subs. The best options for an even frequency response aren't going to be doable in this situation and if I remember correctly, the next best setup was a subwoofer in each front corner. No matter what you do there are going to be dips and there are going to be differences between the various listening positions. And that's why I suggested the use of bass traps (especially in the rear corners). A broadband solution is ideal here because though it attenuates all the frequencies, it will have a larger impact on the destructive interference (thus resulting in a reduction of the peaks). The peaks will never be flattened out perfectly either, but you will reduce the RT60 at those otherwise resonate frequencies. So ya, this probably a bit too technical for the average reader so allow me to conclude that there is no way really to decide upon an "ideal" location unless someone wants to sit down and model the entire system. I can however think of a few benefits for the corner loading though. And I also wanted to point out that the majority of the listening positions are going to be in the "power ally" which is the spaced array problem that was being brought up...in other words, it's most likely not going to be an issue in this situation. (If anything, the narrowed polar plot is going to minimize the build up in the corners). Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted January 25, 2006 Share Posted January 25, 2006 Vote Pedro Quote Link to comment Share on other sites More sharing options...
Chris Robinson Posted January 25, 2006 Share Posted January 25, 2006 Vote Pedro Ah, I love that movie! I love Dr. Who. Hard to believe he's like twelve years old or something [] Quote Link to comment Share on other sites More sharing options...
DrWho Posted January 26, 2006 Share Posted January 26, 2006 Ok, here's the article: http://www.harman.com/wp/pdf/multsubs.pdf If you're just looking for their conclusions they can be found on page 28. Flattest response is obtained with subwoofers at midpoints on opposite walls (which is that optimal situation I didn't think was feasible here). And corner loaded subs are the next flattest and also offer better LF extension...the Ultra2's can dig 'flat' down to 16Hz in the right situation [H] Also, 4 subs seem to be the point of diminishing returns, but you don't sacrifice much by going with just two. On a psychological level I've never enjoyed having a subwoofer behind me...even with very low crossovers and very clean speakers. Quote Link to comment Share on other sites More sharing options...
formica Posted January 26, 2006 Share Posted January 26, 2006 you'd be better off putting that side surround forward...like in front of that pillar just above the fireplace...which would also be close to that location you labelled "doesn't line up with other wall") Unfortunately true... the side surrounds are ideally place to the sides of your first row of seats, while the rear effects are ideally placed behind your second row of seats. Placing both subs in the center is going to shift (not remove) a set of nodes and double the magnitude of the horizontal nodes. So what we have here are two competing systems: comb-filtering from spacing the array and the complex nodal structure of the room. I don't think comb filtering will be a factor at those frequencies esp with the subs placed right next to each other (or up to 1/2 a wavelength apart). Either option will have it's good and bad points.... but the subs can be moved around once the room is finished anyways. No matter what you do there are going to be dips and there are going to be differences between the various listening positions. ........ So ya, this probably a bit too technical for the average reader so allow me to conclude that there is no way really to decide upon an "ideal" location unless someone wants to sit down and model the entire system. Basically the gist of things... Sterling... you're on your way to a really killer system and HT. I don't think your dilemmas are major comprimises at all. Every HT build has a bunch of small compromises... but like Chris said... nothing major and it'll be a great system. ROb. PS: Mike, you have way to much time available to you during class... whatever happened to exciting subjects like "fluid mechanics"? [] Quote Link to comment Share on other sites More sharing options...
DrWho Posted January 26, 2006 Share Posted January 26, 2006 but the subs can be moved around once the room is finished anyways. I think he's looking to cut out drywall for a flush mount approach? That was the impression I got (in which case they couldn't be moved) [:/] PS: Mike, you have way to much time available to you during class... whatever happened to exciting subjects like "fluid mechanics"? [] Thankfully I don't have to take fluid mechanics...that only works towards an ME degree (I'm doing EE). I am taking a grad level acoustics course though....I had no idea there was so much math involved [] At least the prof really knows his stuff. Quote Link to comment Share on other sites More sharing options...
Stimy Posted January 26, 2006 Author Share Posted January 26, 2006 You guys are UNBELIEVABLE!!! I had no Idea of the wealth of knowledge in this little post. Anyway I will go ahead and place a THX ultra 2 inwall above my fireplace and paint it as good as I can. I just took pics of the new line from Klipsch at the CES show and they look like there going to perform well they have the box built around them witch should help. About the sub issue I have wired for my subs to be in the front corners but I can wire other places just incase. If I try them in the middle of the front stage I will have no where to place my center channel. As far as Acoustical treatment goes I will have real shaggy carpet and I plan to have two leather couches in the tier and in front. maybe a Love Sac or two in the front of the room also. So for the back wall would two panels work? what size? also the bass traps? how big are they and where do they go? Again thanks so much for the help I feel like I owe you something for your intellectual property!!! Quote Link to comment Share on other sites More sharing options...
Stimy Posted January 26, 2006 Author Share Posted January 26, 2006 Another CES pic Quote Link to comment Share on other sites More sharing options...
Stimy Posted January 26, 2006 Author Share Posted January 26, 2006 Back of the THX ULTRA 2 in-wall Quote Link to comment Share on other sites More sharing options...
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