New construction - home theater

[Scoobydufus]

Hi all,
I'm building a "somewhat dedicated" home theater room in my basement this fall. Currently, the basement is unfinished, meaning nothing but cement block and one big room. Anyway, my question is whether to build a 45 degree angles into the corners of the room rather than square. Does this help with reducing bass reflection (or any other frequencies)? Or could this actually end up making it worse?

Attached is drawing of my proposed floor plan. The only questionable thing is the 45 degree angles in the corners (three of the corners, anyway).

Also, any other "low-cost" construction tricks I can do to improve the audio now before it's too late? I'm actually looking to start framing next weekend.

Your advice/opinions are greatly appreciated!

 

[bpape]

DO NOT, under any circumstances drywall off the corners at 45 degrees. The corners are prime location for broadband absorbtion and the airspace behind treatments straddling those corners will only help them perform into the lower frequencies.

The most frustrating designs I work with on a daily basis are those where someone who has done what you are considering. Take advantage of the natural places for treatment that most rooms provide - don't take them away.

Bryan

 

[Buckeyefan 1]

Some things I would recommend would be to use drywall screws instead of nails, and really secure your framing to the ceiling and floor. Insulate well between the basement and next level, keeping the sound in your HT room.

Use carpeting instead of tile or hardwood floors, and use a nice thick. I would also recommend spending a little extra for 5/8" drywall. I used metal studs to finish my basement because I wanted everything square. I didn't insulate - thinking it's already underground, but my first goal was a game room, not an HT room. When the bass hits hard with my music system, you can hear the ducts rattle, along with the ceiling. Most of that went away when we tiled our kitchen, and screwed down cement board to the floor above the basement. We had just purchased our house, and funds weren't all reserved for my "boys room."

My new rule of thumb is to spend more on the materials up front - they're inexpensive compared to the issues you'll have later on if you go cheap.

 

[mtrycrafts]

Hi all,
I'm building a "somewhat dedicated" home theater room in my basement this fall. Currently, the basement is unfinished, meaning nothing but cement block and one big room. Anyway, my question is whether to build a 45 degree angles into the corners of the room rather than square. Does this help with reducing bass reflection (or any other frequencies)? Or could this actually end up making it worse?

Attached is drawing of my proposed floor plan. The only questionable thing is the 45 degree angles in the corners (three of the corners, anyway).

Also, any other "low-cost" construction tricks I can do to improve the audio now before it's too late? I'm actually looking to start framing next weekend.

Your advice/opinions are greatly appreciated!

If that layout to scale with the couch the room looks big enough for a 6.1 setup on the back wall.

 

[Jack Hammer]

Add the additional cable now...

If that layout to scale with the couch the room looks big enough for a 6.1 setup on the back wall.

Even if you currently are not interested in a 6.1/7.1 setup, it will be worth it in the long run to add wires for rear surround speakers. You don't have to use them now and you may never use them, but it's a lot cheaper and easier to have them and not need them than it is to decide a few years down the road you want to add them. A single 2 pair wire should be cheap and easy to run.

 

[Scoobydufus]

DO NOT, under any circumstances drywall off the corners at 45 degrees. The corners are prime location for broadband absorbtion and the airspace behind treatments straddling those corners will only help them perform into the lower frequencies.

The most frustrating designs I work with on a daily basis are those where someone who has done what you are considering. Take advantage of the natural places for treatment that most rooms provide - don't take them away.

Bryan

Thanks for the info, Bryan. It sounds like you have the expertise in this area. I checked out GIK Acoustics and found the tri-trap. I'd like to know how this differs from what I was considering. Or is it completely different because drywall is more sound reflective instead of absorbing (as in the tri-trap)?

Also, I've noticed that you've got quite a few acoustic panel options at GIK. Curious if you could make some recommendations on treating my room layout for home theater use.

Thanks again for your response!

 

[Scoobydufus]

Buckeyefan,

I don't believe it's a good idea to screw the walls securely to the floor and ceiling, at least for sound proofing, which is also important to me. I was thinking of installing resilient channels on my ceiling to offer the flex and de-coupling from the upper floor joists. Although, I'm not sure I'm gonna do this. I might just insulate between floors and call it good!


Mtrycrafts and Jack Hammer,

Thanks for the 6/7 channel idea. For some reason, that never actually crossed my mind to at least pre-wire it for the option later. Thanks!

 

[Bryce_H]

See my response in another thread here

Note: the link to Home Theater Forums thread has changed to this

Good luck.

 

[Buckeye_Nut]

Scooby,

I have 10 of the GIK 244s in my HT, and they made a huge difference in the sound of my theater. I'm not the expert, but I'll give you my 2 cents on how I would treat your HT room if that was my room. I would have purchased some Tri's, but they didnt exist at the time of my purchase. Instead, I went with 244s all the way around.

1. If you have a full 8 feet from floor to ceiling, I would put tri-traps 'floor to ceiling' in the three corners. If not, I would just put one in each corner.

2. I would place 1 or 2 of the 244 panels on the front wall to absorb front wall reflections, and treatment will depend on your screen size and available wall space.
This is how I did my front wall, and having the panels situated they are made a big difference. Having absorption there really cleaned up the sound coming from the front. My front/left corner is one of those crappy 45degree corners!! Whatever you do... dont do it!!
View attachment 3641

3. Treat first reflections on the side walls. The left wall is tricky because of the utility room doorway and AV rack. I'm obsessive, so I would probably drive nails into the door, and hang a 244 right on the door. LOL
I also might hang another between the door and AV rack if there is 24" of wall there to play with. I'd also hang two panels on the right wall at the first reflection point, and possibly one or two on the back wall behind the couch.
This is a back/right corner view that shows a variety of treatments, so you can see various application possibilities in use.
View attachment 3642
In this photo you can see 1 of the sidewall panels. You can also barely see one laying on the floor with an airgap behind the sub as well as a corner mounted panel.

The end result will be phenomenal!! Good luck and happy shopping!!

 

[bpape]

Due to the thickness and density of the drywall, what you're proposing will work the same as any other wall - it will act somewhat like a membrane absorber that's tuned pretty low and only function decently over maybe an octave.

The Tri-Trap will function as much more of a broadband absorber with a rolled off absorbtion curve at the top end to allow good blending with reflection panels without overdeadening the highs in a room.

Even if you don't purchase our product and decide to go wtih someone else, my advice would still be the same. Use the corners for good broadband control. If after treatment, proper setup and placement, and some parametric EQ on the sub to tweak the few stubborn peaks - you still need more - THEN you might consider building some tuned membrane absorbers - but specifically tuned and placed to deal with the specific issues that you have remaining.

Bryan

 

[chas_w]

How important is it to treat the front wall (behind the front speakers)? I notice that panels are often placed behind the front three speakers.

 

[chas_w]

Scoobydu - what equipment will you be using in your theater?

 

[Haoleb]

Also, Dont forget to run a couple dedicated 20 amp lines, One to the Head end and one to the front by the display.

I also see alot of sealed off wasted space. Why?

 

[Scoobydufus]

Thanks for all your responses/replies. I modified my plan a bit, getting rid of the 45 degree corners. Instead, in the front, I'm putting a a little bump out in the wall at the left and right ends. (see attached pic) They will be rectangular, not at 45. Why am I doing this? It's partially necessary since I've got some plumbing on the left side that would require a small bumpout anyway, so I figure I might as well even it out by doing it on the right side as well. Besides, it gives the room a little bit of architectural character, which is what I was looking for anyway.

Buckeye_Nut, thanks for the advice and pics of your HT. If I had the money, I'd buy a bunch of those GIK panels, too. I certainly consider getting a few and experimenting with locations.

The equipment that I will be using in this theater is:

• Ceiling mounted front projector (still deciding on brand/model)
• Ascend 340SEs for L/C/R, and 170SEs for surrounds
• HSU VTF-3HO subwoofer (front right corner)
• Dayton Sub-120 subwoofer (maybe front left corner, or maybe not at all)
• Pioneer Elite VSX-72TXV receiver
• Crappy RCA dvd player

I do intend to run a dedicated 15 amp circuit for just the AV Rack equipment. Not sure it's really necessary to do a 20 amp.

I'm planning on either a 109" or 120" screen. Either case, I want it fixed permanently to that wall. Also, I'm looking for information on painting it (either with cheap white paint or the special $300-$400/gallon paint. Any experience using the expensive stuff? Or does anybody sell a good "cheap" screen, like under $500-$600?

Haoleb, I do have some sealed off wasted space, but it's not without reason. The only significant space I'm bummed about is by the bathroom shower. There is some plumbing in there that can't be moved. Otherwise, I'd probably make a closet out of that area. The triangular space in the bedroom closet could be kept open, but I was thinking about building a nook from the theater room side, possibly for shelving for dvds/cds.

Thanks again all!

 

[starshipwarrior]

New0b

First time here First post (dont you feel luckey LOL

Why is your equipment rack on that side of the door is this the pumbing you are talking about ?

Starship Warrior

 

[bane1202]

Painted on screen

If you were looking for a painted on screen http://www.goosystems.com/ makes a very respectable product. Comes in four shades if memory serves (white, and 3 grays). Theres a decent writeup on http://www.projectorcentral.com/home_theater_screens.htm . You're not going to get world class performance out of it but you're also not paying $2000 for a screen either. Those kits they sell come with matte black paint but if I were you I would buy some black velvet and use 2x1's for making a frame around the screen and cover them in the velvet. Also instead of painting it directly on the wall go to lowes and see if you can find some 1/4" MDF or some other ultra smooth paintable surface and just hang it on the wall. You could screw it directly to the wall studs around the perimeter and overlap the border to cover up the screws. You may want to put a felt backer between the screen board and the wall to prevent your sub from having a field day with it. Oh and defilitely run a 20 AMP circuit especially if you are thinking of running double subs. Big spikes in power draw from bass heavy scenes might trip a 15 amp circuit.

 

[NickFournier]

The only problem with using 1/4" MDF would be the seams. With a screen size that big you're going to have seams regardless. If you were doing the drywall yourself I would pay special attention to that area if you decide to do the projector paint. Unless you're really good at taping and mudding you might want to hire a pro for that part and ask for a level 4 finish. I do like the idea of a black velvet frame too.

Nick Fournier

 

[bane1202]

4x8 sheet is about 98" on the diagonal for a 16:9 picture out to the edges if my math is correct. ive seen 5x10s before of both mdf and cement backerboard. if you have a lumber supplier close like 84 lumber you can usually find the special sizes. like nick said I might consider a contractor if you were going to paint it directly on the wall without hanging a board. ive seen a lot of do-it-youselfers not get the framing exact and end up with bows or humps in the drywall