New wall construction for In-walls

[---k---]

My next project is going to be some(big) in-wall surround speakers. My plan build box speakers as normal and then have niches built into the wall that the speakers can sit in. That way if I ever move, the speakers can be pulled out and someone else can have niches to put nick-nacks on or speaker. My better half would also like some in-wall bookshelves to reclaim a little space. Sounds like a good compromise.



I'm currently thinking I'll have a contractor tackle this. I could probably do it, but right now I don't even know where to start on the trim and finishing. And, it would probably take me 2 months to do where as a contractor can probably knock it out in 1-week. My wife is pretty tolerant of my projects, but having the house torn up for 2 months wouldn't fly. I'm also hoping I can find some contractors hungry for work this winter.

I thought before I go looking for a contractor, I would post a picture of what I'm thinking and see if anyone has any suggestion on layout or construction.

The wall is about 13.5' wide (plus 3' for the stairs and the room is 16.5' wide). Behind this wall is a utility closest and the crawl space that is accessed from the door on the left. There is a pole near the middle, on the left side of the jog in the wall, and a HVAC cold air return on the right. The closet is about 4.5 feet deep, with 3' from the back of the wall to the hot water heater. The rest of the room has a ledge at around 48" up and wanes coating below.

I'm thinking I'll have the wall moved forward a few inches and get rid of the jog. Then add two 12" deep in-wall bookcases. Probably make them nearly 48" tall so that the trim on them would match the rest of the room. Then I would have three niches built in the wall above for 6.1 surround sound. (I absolutely can not place speakers on the side walls because of windows.) That light on the back wall is going to be gone.

Any thoughts?

And, if anyone can recommend a cheap contractor in Chicagoland...

[---k---]

Wow. No comments? I was expecting people to tell me I needed double layer drywall and 2x6 construction (I'll probably not do either). Or maybe that it wouldn't be that hard and I should do it myself.

[Paul W]

I suggest reading Floyd Toole's new book on Sound Reproduction before you cut holes. The book is weighted toward multi-channel and written in a very approachable style. He has convinced me to change my plans for surround and I haven't even finished the book! A very worthwhile $45 at Amazon.

[dlneubec]

Ryan,

I don't have any suggestions on the in wall construction, but will tell you what I envisioned when I saw you photo. Construct some built-in, on wall rather than in wall, cabinets the full width of the room from stairway opening to door, at the hieght of the chair rail. You could extend the HVAC through to the front or the side of the right end of the cabinets. Cabinets would have a combination of doors and open shelving. Then you use the top of the cabinets to set your speakers on. That way you would have room for whatever speakers you like, without height X width limitations.

Then maybe install some nice indirect lighting above the cabs and speakers to shine down, or up, on that wall. Remove the speakers and a future owner could add art pieces along the wall or on top of the cabs, lighted by the indirect lighting. I could see some nice exotic hardwood veneered speakers (I know, not your specialty) setting on some tall spikes with discs under, lit from behind :E

You get the custom built-in look (though not reclaiming space) but it would be more flexible and much cheaper from a construction standpoint.

[Dennis H]

I suggest reading Floyd Toole's new book on Sound Reproduction before you cut holes. The book is weighted toward multi-channel and written in a very approachable style. He has convinced me to change my plans for surround and I haven't even finished the book! A very worthwhile $45 at Amazon.

So, what's the plan now for your surrounds?

[Paul W]

Hey Dennis,
As you know I had considered doubling the number of surrounds for a more diffuse presentation with placement at +-70,110,150, and 175 degrees (3 front/8 surround). The idea was HRTFs would decorrelate signals hard panned to the side and prevent any oversized images...like a 40' guitar. Couldn't find enough info to validate the idea so I settled on, and started to build, a fairly standard 3/4 DTS configuration at +-90 and 150.

Fast forward to Toole's book and, for a number of reasons, he encourages a 3/6 arrangement at +-60,100,150. Other than eliminating the center rear, which he says adds very little to envelopment, the big difference between his layout and my original thought is that he clearly states the additional channels must be decorrelated using additional delay...that's the key I was missing.

The DTS in-wall setup is framed but nothing that can't be changed with 2-3 days work. Still reading the book so nothing is set in stone.
Paul

[cjd]

Ryan, any chance we could consider something further outside the norm for your side surrounds such that they're stand-alone?

[BeerParty]

I'm thinking I'll have the wall moved forward a few inches and get rid of the jog. Then add two 12" deep in-wall bookcases. Probably make them nearly 48" tall so that the trim on them would match the rest of the room. Then I would have three niches built in the wall above for 6.1 surround sound.

So would you move the wall forward and then add an additional 12" for the bookcases, or would the bookcases be built into the new wall space?

[---k---]

Ryan, any chance we could consider something further outside the norm for your side surrounds such that they're stand-alone?

Don't know. I guess it depends on what you had in mind.

The big thing is that this room is the most used room in the house. We both spend a lot of time in it. We do almost all of our entertaining and such in it. It has to look decent. Thus far, my wife has been very reasonable with what she allows. Exhibit 1 being my subwoofer. Exhibit 2 being 54" speakers. (Though, I do allow her treadmill in MY Room!) But in the end, rear / side speakers isn't worth any fight. My current rears are very acceptable as is. I probably should just leave it as is. But I want more!!! :evil: So, I'm trying to do as much as I can by doing as little as I can. (Make sense?)

My wife very much likes the idea of getting the speakers off the back wall and into the wall to clean the appearance up. My current speakers are a bit large hanging on the wall and really draw attention to themselves. I think going full in-wall will allow me to go with the bigger 3-way speakers I'm wanting.

What I'm thinking is that I will need to move the wall forward about 6" to maintain the 3' from the back of the book cases to the water heater. --I need to check to see if this is code or if it is less--

Dan, I like your idea. But I think right now the idea is to hide the speakers. 2 big monstrosities is enough in the room.

Paul,
I'll have to see about picking that book up. Can you explain a bit more what the 3/6 arrangement is? As I tried to explain, the side walls are basically out, so I'm limited in what I can do. I'm not shooting for the ultimate experience, just a little bit better than what I got now.

[cjd]

Speaker-wise, I was thing some nice plant (or art) stands. Omnipoles. Probably would still be really tough to work into your room though. That stupid pillar really is limiting. You should make a comfy little nook for the chairs and "bridge" over them to support the beam and get rid of that pole.

[---k---]

The pole! I know! You know, I once ran the calculations to see what type of beam it would take to carry the loads. I even had my wife on board, because we had just moved in and nothing was in the room. Unfortunately, it wasn't pretty. Even if I put two steel beams side-by-side it was pretty deep. And I would have had to upgrade the existing foundation to support it.

The room unfortuantely isn't that big. It looks bigger than it is. But when you put two sofas, two chairs and a 400L subwoofer in it...

[Paul W]

Ryan,
3/"n" is just Toole's shorthand for the three front channels (left, center, right) followed by the number of side and rear channels. 3/2 = 5 channel, 3/4 = 7 channel and so on.

You may not be up for 6 surround channels, but the book is an excellent practical treatment of human spatial perception coupled with speaker & listening room interaction...so it is extremely useful regardless of the number of surround channels you want to implement.
Here's a review by S Linkwitz:
Linkwitz review
Paul

[---k---]

Paul,
That looks like an excellent book. I spent about 10 minutes reading it using Amazon's "Look Inside" feature. I kept hitting the Surprise Me button until it showed me the pictures of different surround sound format. I must have skimmed over about 20 pages of the 400 pages. It really looks like an impressive book.

Though, I fear that if I read it, it would just depress me. I saw the pages recommending multiple subs and 6 surrounds. I'm pretty happy with what I have now. I think the book will just point out all those areas I'm not "theoretically" correct.

I still may pick it up though. I put it in my Amazon wish list. So thanks for pointing it out.

[Dennis H]

Fast forward to Toole's book and, for a number of reasons, he encourages a 3/6 arrangement at +-60,100,150. Other than eliminating the center rear, which he says adds very little to envelopment, the big difference between his layout and my original thought is that he clearly states the additional channels must be decorrelated using additional delay...that's the key I was missing.

Sounds like he's assuming a 5.1 input signal -- 3 front and 2 surround inputs? Where do 7.1 Blueray and 7.1 matrix decoders fit into that picture?

[blue934]

he encourages a 3/6 arrangement at +-60,100,150.
Paul

paul, how would you power this arrangement with an HT reciever (9.1)? or would you have to use a multi amp config? or am i just misinterpreting you?

blue934

[Paul W]

Sounds like he's assuming a 5.1 input signal -- 3 front and 2 surround inputs? Where do 7.1 Blueray and 7.1 matrix decoders fit into that picture?

Haven't yet seen a reference to source for this scheme...just halfway through a full read + a little glance ahead. I'm assuming we would use the side surrounds at +-60, delay them for +-100, and use the rear surrounds normally at +-150. Multiple possibilities.

paul, how would you power this arrangement with an HT reciever (9.1)? or would you have to use a multi amp config?

I'll use multi-amp with a digital delay box. I seem to recall some of Yamaha's receivers have more than 7 channel matrix systems...those might fit well???

[---k---]

, he encourages a 3/6 arrangement at +-60,100,150.
Paul

Ryan,
3/"n" is just Toole's shorthand for the three front channels (left, center, right) followed by the number of side and rear channels. 3/2 = 5 channel, 3/4 = 7 channel and so on.
Paul

Wouldn't 3/6 = 3 front + 6 surrounds? Or 9 channels?

Bu, I'm confused about eliminating the back channel. Are the 3 surrounds on each side all the same signal?

[Dennis H]

I'll use multi-amp with a digital delay box. I seem to recall some of Yamaha's receivers have more than 7 channel matrix systems...those might fit well???

Paul,

Some guys over at AVS have used an old (circle surround?) matrix decoder box that you can get cheap on ebay to do more than 7 channels -- splits any 2 channels into 3 channels. Dunno if it works better than a simple delay.

The Yamahas have some front speakers that mount up high but they only play using the Yamaha DSP modes and I don't think that's what you are looking for.

Bu, I'm confused about eliminating the back channel. Are the 3 surrounds on each side all the same signal?

Ryan,

That's the only way I can see it working but it seems like old tech to me. Modern receivers have already moved beyond that. Shrug. Nobody has used a single rear center for a long time. Two rears sound better.

Can you use free standing side surrounds? Say an omni design with a piece of PVC pipe or a small wood column about ear height and a fullrange driver like a TB W4 on top firing toward the ceiling? SL used something like that for his surrounds before he decided the Orion didn't need surrounds. Later he built on the concept with his Plutos.

[---k---]

Can you use free standing side surrounds?

I don't think it isn't that important to me to have the sides. I know it would be better, but maybe some day in the next house.

Any suggestions on simple wall construction that isn't obvious? I'm thinking it should be pretty straight forward.

[cjd]

Ceiling an option? I was thinking omni, though.

[Paul W]

A little more reading/information. He does mention Blu Ray, lossless audio etc, but just as increasingly evolved delivery vehicles. "With steady progress in surround processor developments, it is probable that high-end models will one day provide processed outputs for more than four surround channels... In the meantime, there are several outboard multichannel digital delay/equalization/crossover processors avaliable in the professional audio domain that are extremely useful in these applications."

The main thrust seems to be resolving the spacial inadequacy of stereo by increasing apparent source width and listener envelopment via delayed, decorrelated, reflections (multichannel). Directional movie sound effects get a free ride...so music and movies are served by the same high quality system.

Dennis,
Hadn't thought about eBay for old surround processors. Might give that a try if I can't squeeze what I want out of a spare DCX2496. (Yamaha is out for several reasons.)

Ryan,
You might take a look at pages 292-305 where several studies and specific options are discussed (including the center rear). The surprise for me was the strong performance of side surrounds at +-45 to 75 degrees (in front of the listeners). Can you do anything outside the left and right mains? Other takeaways from the book: in-wall :T , on-wall bipole :T , on-wall dipole :throwup:

[BeerParty]

Any suggestions on simple wall construction that isn't obvious? I'm thinking it should be pretty straight forward.

How far out into the room can you bringing the wall? You might be able to leave the current wall where it is and build a false wall in front of it, with enough space between the new and old wall for the bookshelves and speakers.

Or you could do what dlneubec suggested and instead of a new wall, have custom cabinets built that would fill the wall. This would be the least disruptive (no demo work) and would provide a lot more storage space. It would also be the most expensive... :|