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Discussion Starter #1
I have built a dedicated theater over the garage - in the attic space. No windows, with about 22 x 15 ft room. While under construction, I thought creating columns in the room to add looks and also "to break up the audio waves, and create better acoustic design". Well, that was before I had time to read anything for acoustics.:rubeyes:

Now, I think I may have made mistake. I have attached the line drawing of my theater room. I am not good at CAD or sketchup, so I used simple line drawings. The jpg shows footprint of the room and gives a good information about the columns I mention. The pdf shows how the room is insulated. The blue line shows minimum of five inch of Icynene insulation. Underneath the room is garage, separated by 2"x 6" and mostly filled with icynene insulation. The theater room walls are not insulated or filled with any material, just 2"x4" and the sheetrock. However, immediately outside that there is about 5 ft of attic space with is insulated on the outer side with this Icynene. Same goes for the roof. The room ceiling height is 8 feet in center but has vaulted ceilings on sides bringing them to six feet.

Now, my dilemma is should I just add acoustic treatment in corners, and some on the walls? or should I remove the columns and add acoustic treatment. If I remove the columns my wall treatments will include 2'x 4' of 4 inch 703 boards, in place of the columns. The corners will get the same treatment. I would appreciate any help from experts here. Should go through the pains of removing columns or it will not make much difference. I need to know this soon, as I am getting ready to order the carpet.

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BTW, I am planning to put Panasonic AE4000, Black widow CinemaScope screen. With Black widow providing about 0.88 gain, I need to place the projector as close as allowed (14 ft from screen) to get my 10 ft wide picture and decent brightness (12-13 fl per Projector central calculator). If anyone has experience with this projector and black widow screen, please provide feedback about my idea also. If this is off topic, you may choose to send pm to me. Thanks.
 

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The columns will help break up the large walls - no problem there. Generally, we'd put the columns where we can hide surround speakers in them.

If the rear side of your walls is not drywalled, then the attic space insulated will be fine.

With that much space, you should be able to use a larger riser and get the back row away from the rear wall for better bass and surround performance.

Bryan
 

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The columns will be fine, but you will also need wall panels..
Just first check where your first and second reflections points will be, and then the columns can placed either side of where the panels are going..
The rear columns may be a good position for the surround speakers..
 

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Discussion Starter #4 (Edited)
Thanks a lot guys. That saves me a lot of work too. I do plan to place acoustic panels. I will end up using about 18 2'x4' 2 inch thick panels according to my plans. I will attach some diagrams later. Will add about 3-4 more to make a door at the entrance to try to isolate sound to the rest of the house. (when I am watching movie and kids are sleeping) I am not a audiophile, and I am not sure if I would want to put lot of money in speakers. So, I have been thinking of putting in wall front and surrounds. The rear wall has icynene so cannot place inwall speakers there, and will use bookshelf. I already have a klipsh center channel. For the inwall speakers, I am thinking of Hometheaterdirect.com stuff. Does anyone have any experience - good or bad about them? For subwoofer I am thinking of svsub - probably PB12-NSD - may be two of them!

For the acoustic treatment and making proper adjustments, does anyone here offer any services, or am I better off buying the mic and doing my own measurements?
 

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Thanks a lot guys. That saves me a lot of work too. I do plan to place acoustic panels. I will end up using about 18 2'x4' 2 inch thick panels according to my plans. I will attach some diagrams later. Will add about 3-4 more to make a door at the entrance to try to isolate sound to the rest of the house. (when I am watching movie and kids are sleeping) I am not a audiophile, and I am not sure if I would want to put lot of money in speakers. So, I have been thinking of putting in wall front and surrounds. The rear wall has icynene so cannot place inwall speakers there, and will use bookshelf. I already have a klipsh center channel. For the inwall speakers, I am thinking of Hometheaterdirect.com stuff. Does anyone have any experience - good or bad about them? For subwoofer I am thinking of svsub - probably PB12-NSD - may be two of them!

For the acoustic treatment and making proper adjustments, does anyone here offer any services, or am I better off buying the mic and doing my own measurements?
If the center is a Kilpsch then I suggest sticking with horns through the whole front stage.
http://www.klipsch.com/na-en/products/architectural-speaker/

I suggest sending GIK an email regarding the acoustic panels. They are great to work with and really know their stuff. http://www.klipsch.com/na-en/products/architectural-speaker/
 

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General treatment plan:

Broadband bass control full coverage in the front corners.

Full coverage of the balance of the front wall with 2" OC703 or similar

Side wall reflection panels

Rear wall - I usually recommend some bass/lower mid absorbers on the rear wall to help with cancellations off the rear.

Bryan
 

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Discussion Starter #7
Bryan,

You have mentioned several times in various threads, about not placing the subs in corners. This will change my plans:scratch:

If I understand correctly, low frequency sound should be well transmitted through the drywall and most material. How would a corner placement of sub cause distortion?

Also, If 4 inch of 703 or 5 inch of Quietbatt - each with NRC at 125 Hz of 0.6, is placed on three or four sides of the sub, would that alleviate any problem of placing the sub in a corner?

I have uploaded diagram of my theater screen wall. The large white area under the screen is 22 inch high, 10.5 feet wide and about 24 inch deep hole - I had created to place equipment and possibly speaker, DVD collection etc. With ever changing plans, I have now thought of placing subs as noted. Center channel as noted. I will place front right and left either as tower on sides of the sub, in front, or in wall over or on the blue area. The blue area is - my newest plan - 2 or 4 inch of 703 panel, in a form of a door. At the top of the screen and sides I will hang heavy fabric for decoration. At present all surfaces are 1/2 inch drywall. But if necessary, I can remove drywall from top and back of the sub locations. I was thinking of placing 2-4 inch of 703 with or without the drywall and keep the subs as planned there. To start with, I will likely have one sub only. What is your recommendation? Also, you recommended treating the front wall, however, as front wall is mostly screen (black widow paint over drywall for now - may change to fabric or something later), how can I treat the front wall?

Obviously I will be getting a mic and doing all the testing once the carpet is in and then try placing the treatment and again after turning the subs on. Once I do that, (may be 1-2 months from now!!!) I will post graphs.
 

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Corner control will help with the room acoustics but will not make up for frequency response issue caused by errant sub placment. The drywall acts as a boundary and effectively, a horn.

Bryan
 

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Discussion Starter #9
Thank you. I can understand that. Will any of following modification help avoid any distortions?


1. Move the subs inwards and remove the drywall above and behind, leaving about 1 foot or more open space on each side with back and top completely open - only the studs - And placing the treatment as I mentioned earlier.

OR

2. Only one sub in the center, front speakers on sides of the sub, with all drywall from back of the "hole" and top of the "hole" removed, replacing with 2 inch 703. In this case, I will relocate the center to top of the screen and somhow hang it. And move the equipment to sides, behind the door.

OR

3. Just not have any sub under the screen and bring it out. Would placing front speakers in that area be okay or I should not do that either. For front right-left I have not decided to get tower, bookshelf speaker or "in-wall" type.
 

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Any speaker that's not designed to be mounted into a wall, should not be. The cavity will resonate like mad and the speakers now think their baffle is as wide as the entire room which will mess up the xover compensation.

Ideally, the best thing to do is pull off ALL of the drywall and just cover with cloth grilles for the false area.

Bryan
 

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Discussion Starter #11
Ideally, the best thing to do is pull off ALL of the drywall and just cover with cloth grilles for the false area.

Bryan
That is what I was referring to. The cavity has drywalls on the sides (10.5 feet apart), back and top. Obviously the top wall is behind the screen wall. This top and back opens in to attic space that is about 6.5 ft high, 20 ft wide and about 10 ft deep behind the cavity. The roof has Icynene foam - at least 5 inches. If I remove the top and back wall of the this cavity, it would create a potentially large open area under and behind the screen that is surrounded by dry walls on the sides (2 ft x 2 ft) and Advantec floor board on bottom with 5 inch of icynene under that, but open 10 ft back and 6 ft on top. I could place 2-4 inch of 703 in back and top. In front, yes it will have one or several grills.


As the screen goes quite low at the lower end, I do not have luxury to place front tower speakers about 3 feet from the wall, which would probably be better place. I guess, I could keep them at about 2 feet from side walls, and place sub in front of the screen between the speakers. Will get measurements in this positions and discuss treatments. May be I should do that before tearing the drywall apart from conditioned space!


Any speaker that's not designed to be mounted into a wall, should not be.
If I do go with "in wall" speaker, it will be purchased from "in wall" speaker selections.
 

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Yes. PM me and include your phone number if you'd like me to call you to discuss.

Bryan
 

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I already have a klipsh center channel. For the inwall speakers, I am thinking of Hometheaterdirect.com stuff. Does anyone have any experience - good or bad about them? For subwoofer I am thinking of svsub - probably PB12-NSD - may be two of them!?
Klipsch's RB61's are pretty reasonable in price. You would be best to try and match the front three or at least their tweeters. Surrounds aren't as big of a concern, but having the same speakers all around is best. SVS subs are pretty awesome. Two will give you a bit more flexibility, but if it means sacrificing on your front speakers or surrounds I would wait and add one later.
 

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Discussion Starter #16
Exciting Update...

First of all, I am not seeking any help anymore, and hence should change the title of the post, or create a new thread. But, for now I am writing here. I also had another thread for subwoofer build.

Now the carpet is in, and the screen (BW) is done. I still have to finish the subwoofer build and create the screen borders. Will add curtains and such later as time and money permit. I will be checking acoustics soon, and again once the sub is done. If needed (and likely will), I will add sound treatments.

BUT MOST OF ALL, I HAVE BIGGEST NEWS! - I HAVE A PROJECTOR. I was going to purchase Panasonic AE4000. However, somehow got lucky and was given a gift of VIDIKRON model 85. Probably many of you would know that Vidikron is made by same parent company who makes Runco. This particular projector is sold for $16900 new! The one I got is about 2 years old and has about 700 hours on the lamp. Excellent video, with vivid colors. My family and I are excited. Only concern is it is a bit too big. I have is on the floor at present. If I mount in ceiling, it will hang about 1.5 -2 ft from ceiling - so will come down to less than 6 ft from floor and less than 5 feet at the level of riser. That is a problem. I am considering shelf mount in rear or sell it and use the money to buy new projector and new audio system. What a choice? Still thinking. Will post pictures over the weekend.
 
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