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Discussion Starter · #1 ·
Has anyone mounted a DLP in a coffee table for front projection? I would like to try it as I prefer its look to ceiling mounting, and I thought it could also be an excellent hushbox.

What does concern me is the projection angle and potential keystoneing of the image. I know many projectors have keystone correction, however I would prefer to avoid digitally manipulating the image.


The projector will be a Davis DLP, screensize would be about 1.8m wide (4x3), and ideal projection distance from screen would be about 3m.
 

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3 meters may be a little short but you cna check with the screen projection calculator from the davis site to see if the image size and placement is possible...


One thing you may be luck with is the Davis units are not bottom aligned (in a floor mount) and this puts the image higher in your setup than the projector... In general this is bad for HT as you get image shift when zooming between 4:3 and 16:9 making a 16:9 screen tricky (but not impossible you just have to be real careful about placement etc)... I still think that the image will possibly be a bit low down..


Check the calculator...


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HTPC without using windows... GUI Front Ends for Home Theater
 

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Discussion Starter · #3 ·
Hmm interesting, thanks for the reply.

When you say the Davis are not bottom aligned, how does this actually effect its throw?

This would be an advantage to me if the throw was slightly higher. If my coffee table was say 45cm high (with the projector installed slighly below that height), the bottom of the screen would be at about 60-65cm.

According to the davis calculator I am fine for a 180cm wide screen from between 2.59 to 3.95m distance.


I could have a shelf built into the cabinet for the projector that aims it slightly upwards.
 

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I have a feeling you are going to be lucky the image is higher than the projector in a floor mount and lower in a ceiling mount... This is fine if you are using a 4:3 screen (fixed) but awkward because of image shift if throwing to use both 4:3 pillarboxed and 16:9 simply because the image 'moves' as you zoom...


It doesn't affect the 'throw' really (image can still attain x horizontal sizes at y distances but that image will be higher the further back you get the PJ...


I dont recommend angling the projector keystoneing kills an image (for me) and I find that any more than a degree or two is awful...


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Discussion Starter · #5 ·
Well I will be using a 4x3 aspect screen, I just accept I will have to deal with blank screen space on 16:9 DVD's.

I will be bringing home a Davis this week so I will have a test run, get my tape measure out and so what happens! http://www.avsforum.com/ubb/smile.gif

Will let you know.


Now I just need to work out the most effective internal design to dampen the sound to inaudible, as well as finding an exterior design for it that doesnt make my lady kill me!
 

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I recently saw a Runco 3-chip DLP projector floor mounted under a custom made coffee table/hush box. The projection distance was short and the drop down screen was 10.5 feet wide. It looked like it worked out perfectly.


Unfortunately, I can't provide any kind of details as it was a custom installation in a house I was just visiting. All I remember is that it worked well.


Deane
 

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dj,


If push comes to shove, you can always use a "pop-up" installed in the coffee table to increase the height of the projector. There are several manufacturers of the mechanisms for just that purpose. This allows a projector to be used at a height greater than the underside of the table; maybe enough in your particular situation. Some are hydraulic loaded (boosted) and some electric lift. It is possible (and preferable) to build a small hush-box around the unit with down-venting exhaust. Of course the electric ones can be worked into an automated control system - it's very cool.


Thumpers 2c
 

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Quote:
Originally posted by dj:
What does concern me is the projection angle and potential keystoneing of the image. I know many projectors have keystone correction, however I would prefer to avoid digitally manipulating the image.
This is a valid concern. Most of the DLPs that I have seen get distorted when you adjust the Keystone. Also, the long throw distance required for a DLP would concern me as well.


What would be cool is if you could mount it inside the back wall so that only the lens was visable http://www.avsforum.com/ubb/smile.gif



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Mark A. Torre

NEC XG-8"CRT PJ, HTPC, HDTV and loving it! The Torre Home Theater
 

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Discussion Starter · #9 ·
Hi guys,


Projector lifts work great, but then it defeats a big purpose of the coffee table:

1. to act as a hush box - if you raise the projector out, you can hear it!

2. to enclose any light spill from the projector - see above!
 

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dj & bentsai,


The ones I'm thinking of are raw mechanical lifts. You'll need to build a five-sided enclosure with a top (i.e. lid) that normally is made of the same material as the rest of the table top. The PJ is then enclosed on all sides in a pop-up finished box (except the bottom which no one sees anyway and can be used for air exchange). The hydraulically boosted units had a lift cylinder that you released by lightly pushing down to pop it up and you had to push em back down to close it. I remember one cylinder boosted unit that had an electromagnet to hold the thing closed that could be released by a switch or control system (or a power outage) http://www.avsforum.com/ubb/biggrin.gif


If I get a chance, I'll try to look up the info on them. It has been awhile since I installed one that way.


Thumper
 

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Regarding keystoning, I find that as long as you hide the edges of the image in the black border of the screen, a reasonable amount of keystoning is unnoticable, especially when watching movies.


Andy K.
 

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Discussion Starter · #13 ·
Well I am currently playing with the now discontinued Davis DLX650 (800 Ansi XGA), and have tested the projector from coffee table height.

I dont think I could buy anything but a davis- it has a 7degree upwards pitch to its beam, which actually makes floor mounting perfect for my setup.

With ample room for my gear below it, I could get a 2m x 1.5m screen quite nicely, with the top of the projector lens down at 48cm from the ground.

What I will do tho is get a 180cm x 135cm so I can bring my speakers in a bit closer.

Now to decide on screen gain..........it never ends! http://www.avsforum.com/ubb/smile.gif
 
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