Mounting plasma to wall inside large cubby hole - Need guidance please. - AVS Forum
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post #1 of 14 Old 03-29-2009, 03:06 PM - Thread Starter
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Since I have never done this before, I was hoping to get some help and guidance along the way. I have read several threads on the subject here on AVS and have learned a lot.

I would rather ask and do it right the first time (there’s not a lot of room for error on this project). It seems I can save several hundred dollars by doing this myself. Plus, I don’t think this is my last TV that will need mounting.

I upgraded my 6 year old, 42” Samsung plasma to a Panasonic TH-46pz850u 46” plasma which is 46.5” W x 29.6” H x 4.1” deep and 84 lbs. Instead of buying a new Salamander (very low and expensive) stand, I want to mount the TV to the back wall instead, and “float it” toward the top of the cubby hole (with the option to have it recessed or flush). The components will go at the bottom.

It’s going into a built-in bookcase section that is 47” W x 47” H x 29.5” Deep. I will likely use the mount fully extended at all times. Needless to say, final spacing is pretty important. I think the mount needs to go in the middle (at the correct height).

After reading some other threads, I am thinking I will probably go with the Sanus VMDD26.
- Dual cantilever. Rated to hold up to 175 lbs. (850 is 84 lbs)
- It extends to 25.75 inches. 25.75 plus 4 inches for the 850 is 29.75 … perfect.
- It does the various Tilt, Swivel, Pan, and Roll (to level bezel) that I want.
- You have flexibility with stud spacing.
- Lots of satisfied customers using it with big heavy plasmas (including pro-installers).
- People say it’s easy to mount it (I’m going to need all the help I can get).
- Probably overkill for a 46” but I think the extra money is well spent for the insurance.

Like the whole structure, the back is painted sheetrock, built like a conventional wall. I have the pre-sheetrock pictures we took as we built the house (I will use a stud finder and finishing nail when the time comes). It looks like ... 3 evenly spaced 2x4s (the standard 16” on-center). The first hurdle I notice is that the middle stud is basically in the middle of the cubby (with the other 2 studs about 16" to each side). The mounting plate for the Sanus is 26” wide. I would rather not do extra work, but it looks like this requires external framing to go in first. I was thinking (2) 45” 2x10’s lag bolted to the back wall first? ... (horizontally and at the proper height)

First questions:
Did I select a good mount? Does it sound like I need the external framing? Am I on the right track?

Here is a pic of what it looks like now, before I start (still with the old 42" Samsung).


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post #2 of 14 Old 03-29-2009, 09:25 PM
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You can live without the external framing. I had the exact situation with the stud in the center and used the exact mount that you want. Just put the plate from either side stud over the center. It appears that the height is not restrictive, so you have some room for error there. But you need to get what I will call the "carriage" as close to the center as possible. Then you still have 2DOFs on the lateral adjustment. You can move the carriage on the wall plate and you can move the mount at the panel. I don't think this is too difficult.
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post #3 of 14 Old 03-29-2009, 11:17 PM - Thread Starter
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Aymanme,

This is why I love AVS. Same mount ... same problem with studs. Yes, you fully understood my dilemma.

So, you are saying that it is ok to have the plate off-center (so it can mount to 2 studs) as long as you can get the carriage in the middle without it extending off the side of the plate?

How heavy was your TV?

I drew the mount (close to scale) on a photo of the pre-drywall photo. It just looked weird (kinda wrong) and that's why I thought I should ask. However, even though part of the plate and carriage run past the center-most 2x4 by about 5 inches (and aren't connected to anything past that point) the center of the carriage does end up barely between the 2 main 2x4s being used (center stud is actually slightly off-set by an AC outlet).

There is one other advantage to using the framing 2x10s ... it gives me an extra inch or so of extension. I guess the other is that it will look more symmetrical back there. I'm going to stop listing pros now (maybe I secretly like extra work).

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post #4 of 14 Old 03-30-2009, 05:08 AM
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Yes, you can mount the wall plates off-center. The mount manufacturers have already thought of this in their designs. Once the wall plate is bolted in, you can move the carriage on the plate. IIRC, if mounted in this way, you will have ~2" of lateral adjustment on the carriage. My TV was about 90lbs. What it means is that the load will not be evenly distributed about the 4 lag bolts -- however, this doesn't really matter.

The 2x10s will probably only give you an extra 1" of clearance and make the plate easier to center. The only reason that it might make your install stronger is that you spread the load over 3 studs instead of two. However, you should note that the attachment points are where the maximum tension are. Adding wood does nothing for that and if you end up getting less bite into your wood, it is probably weaker.

regards
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post #5 of 14 Old 03-30-2009, 06:31 AM
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Very nice job, but doesn't your neck hurt?
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post #6 of 14 Old 03-30-2009, 10:16 AM - Thread Starter
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Here is a pic. of what we are talking about. This should be drawn fairly close to scale. The back plate is 26" wide, the carriage is 16" wide.

It will be exactly like this, but on the other side of the 2x4s. Since those studs are 16 on center, those 2 boards are 15 apart.

The blue outline is the Sanus VMDD26 wall plate. The yellow is the carriage (centered in the cubby). The C marks the Center of the carriage itself (between the 2x4s a good thing). The gray 4 socket AC power outlet box at the bottom is centered in the cubby.

Notice how a good portion of both hang over the side unsupported (about 5 or 6 inches). I looked through the instruction manual and it does not say anything like DO NOT side carriage all the way over to one side. Or, "Be sure to install lag bolts near the edges of the plate." It's really a combination of the two things that makes it look questionable.


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post #7 of 14 Old 03-30-2009, 10:41 AM - Thread Starter
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Quote:
Originally Posted by Fanaticalism View Post

Very nice job, but doesn't your neck hurt?

Thanks. It was fun designing it and getting the builder to pre-wire. You can't see the JBL surrounds, but they are also free-standing speakers. The Infinity sub is in the back corner behind the couch.

Because of the angle of the pic, I can see why you might think so, but no, it does not. Position 1 on the couch is directly in front of the TV. However, there is a love-seat perpendicular to the couch (out of view). This is why I want to bring the plasma out further.

When you have a fireplace and a TV, only one can be the focal point of the room, so I tried to make the best of what I had to work with.

New Panny gets here tomorrow.

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post #8 of 14 Old 03-30-2009, 04:01 PM - Thread Starter
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Quote:
Originally Posted by aymanme View Post

My TV was about 90lbs. What it means is that the load will not be evenly distributed about the 4 lag bolts -- however, this doesn't really matter.

... The only reason that it might make your install stronger is that you spread the load over 3 studs instead of two.
regards
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Aymna,

So, our TVs weight basically the same ... that's good to know.

Yes, you stated my concerns well there. Those combined with the fact that I would have it fully extended all the time (the leverage factor) ... I just didn't want the "push things" too far.

If using the two 2x10s, I was thinking 10-12 lag bolts into 3 studs. Then, I can use 4 (or even 6) bolts to hold the plate to those. Hmm, sounds extreme now that I type it out, but I think that's right if going that route.

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post #9 of 14 Old 03-30-2009, 04:43 PM
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You should be fine. One thing to add, too late for you now, but a heads up for those that are having use spedific areas built, or the builders(who should know to put it in!) is to put blocking in the walls during construction. Sometimes called cabinet blocking. Not to be confused with fire block. Would be like the 2x10 but inside the wall, nailed to the studs. Then you have a very secure place to center and install your mount. Good luck.
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post #10 of 14 Old 03-30-2009, 06:36 PM
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Yes, but you are sinking the bolts into a 2x10, so you will have less threads catching wood than from the 2x10 to the stud. And the bolts from the mount to the 2x10 would be close to the plane of 2x10 to wall stud. So you don't get much redistribution of the load. Which as far as I see is the _only_ reason to even bother with the 2x10 approach. As a result, I'd say go directly to the stud, use the proper length (and lubricate with soap) lag bolts into the stud and fear not that it is off center. Keep in mind that in a perfectly centered mount there would only (really) be 2 lag bolts supporting the entire load since the top 2 are in tension and the bottom 2 are in compression. In any case, following my own policy of "trust, but verify" -- you can find alot of information about the forces in play in "vector mechanics for engineers".
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post #11 of 14 Old 04-04-2009, 05:59 PM - Thread Starter
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Quote:
Originally Posted by jkxmlr View Post

You should be fine. One thing to add, too late for you now, but a heads up for those that are having use spedific areas built, or the builders(who should know to put it in!) is to put blocking in the walls during construction. Sometimes called cabinet blocking. Not to be confused with fire block. Would be like the 2x10 but inside the wall, nailed to the studs. Then you have a very secure place to center and install your mount. Good luck.

Good idea. Yes, the "blocking" is all over the house, but none there. If only I knew then what I know now.

It's funny. When we started building the house I was going to buy a 40" 4:3 sony CRT (remember those :-). As we got closer to finishing the house, I had decided to buy a rear projection 16:9 Samsung with a new technology called DLP. When I went to the store to shop the DLP, I found this even newer tech... really cool looking TV called a Plasma ... and the rest is history.

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post #12 of 14 Old 07-15-2009, 11:04 PM - Thread Starter
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Well guys, I kinda got side-tracked on this project.

The good news in that the 46" Panasonic 850 plasma has been installed for a few months now and the picture is awesome. I managed to get it in the niche on the existing stand. There is only 1/4"-1/2" space at the top and sides.

About a month after I installed it my 5 year old Panasonic 6.1 AVR went out (constant OverLoad across display).
http://www.avsforum.com/avs-vb/showt...4#post16833414
So, I replaced it with an Onkyo 607. As you can see in the first picture, all the cables are in the wall. I pulled out some and re-wired with 10 ft HDMI (now that I have HDMI abilities) and component cables. 6 footers aren't quite long enough and I also wanted a litle extra since the plasma will eventually be extended out another 6 inches or so.

The guys at Sanus say the slightly smaller VMAA26 Full-Motion Wall Mount is more than enough for my 84lb TV. Its basically a single arm version of the VMDD26. It's rated at 130 lbs. and they say all their mounts are rated to hold 3 times their advertised weight anyway.

I did another template overlay drawing with the VMAA26 measurements. It looks a little different because the back wall mount plate is unfortunately smaller (as it the main mount plate). The Sanus CSR did say the mount plate should be slid as close as possible to the center of the wall plate. He couldn't tell me how far off center you can go without problems (just not to do it).

So, do you guys think the VMAA26 will be ok?


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post #13 of 14 Old 12-11-2012, 09:22 AM
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I saw your signature photos. Just wondering: why didn't you put the TV over the fireplace rather than all the way to the right side?

The area above your mantel is screaming for a lighted painting or something.
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post #14 of 14 Old 12-11-2012, 11:02 AM - Thread Starter
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Quote:
Originally Posted by vivatech View Post

I saw your signature photos. Just wondering: why didn't you put the TV over the fireplace rather than all the way to the right side?
The area above your mantel is screaming for a lighted painting or something.

That space is made for the TV. I think that once you mount the TV above the fireplace, you make a permanent decision to never use the gas fireplace again.

 

We took the painting down. Now, the projector's 96 in.(8 ft. diagonal) image is projected there. I think it looks amazingly good. I need to add a picture of that ... thanks for reminding me.

 

As for the Sanus plasma mount ... I got side-tracked with the projector and new speakers, but I might still do it one day. These multi-function rooms are definitely challenging. Right now, the Christmas tree is just to the right of the plasma.


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