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Why is it that the fan is lounder when you mount a lt150 from the ceiling?

I don't have one yet but what if I had a small suspened shelf from the ceiling? why would that be any louder than it would setting on a table top?


I'm thinking that some of you mount them upside down?



Bill
 

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Yes, ceiling mount requires placing the projector with the top side (the one with the controls) down. This is because there is a vertical offset of the image. The projector was designed to sit on a table and project up to a screen. Placing the unit near the ceiling without putting it upside down merely displays the image on the ceiling. The projector has some passive cooling in that there are vents on the top. Putting the unit upside down causes heat build up and thus more fan cooling (and noise).
 

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Do a search on "hush box" and you will get heaps of info about reducing the noise. I'm currently designing the **ultimate** LT150 hush box ;) , but like all my plans it is long term and probably wont get built until I move apartments next year.


Give me a couple of weeks and I will post some design drawings.
 

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I am not sure but I thought this like most LCD projectors can invert the image internally thus eliminating having the upside down mounting.
 

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Yes it can invert and even flip L and R image but it won't alter vertical offset. It's like aiming a flashlight upward. No matter if you flip the image, it's still shining upward. So you have to flip the PJ to shoot light downward.
 

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On most LCD projectors I have played with, including the ones in my office, all have a setting for table or ceiling mount.


This eliminates the problem you are refering to. I would be very surprised if the LT150 does not offer this.


In fact I was thinking of buying one, but this may be a deal breaker.


More info: I downloaded the manual and indeed the projector can be set up for front projection - ceiling mount.
 

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I think the best way for you to understand is to try with your office LCD PJ. Even if you set the mode to ceiling mount and image is flipped by software, you have to physically turn the PJ upside down to shoot the image downward so it'll hit the screen. This is because most PJ has a permanent upward vertical shift that's not alterable (some do have lens shift optically but those are rare and more expensive). Thus, if you don't flip the PJ physically (have top of PJ downward and bottom of PJ towards ceiling), image (although flipped already by software) will still hit the ceiling due to its permanent upward vertical offset. Try it with your LCD PJ in office as it's probably the same way. You can not do ceiling mount without flipping PJ physically upside down which builds up more heat as heat rises back into PJ casing so fan goes automatically to high speed (higher pitch noise) to compensate.
 

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I understood what the issue was. I was merely stating that I have used PJ's with this feature. I was hoping the LT150 had a similar feature.


On my office PJ we do not have to turn it upside down. It automatically shifts the image to project down instead of up.


According to the instructions for the LT150 it has a ceiling front projection option. Maybe it is not properly explained in the instructions and all it does is just simply flip the image.
 

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Quote:
Originally posted by Paul Hives
I understood what the issue was. I was merely stating that I have used PJ's with this feature. I was hoping the LT150 had a similar feature.


On my office PJ we do not have to turn it upside down. It automatically shifts the image to project down instead of up.


According to the instructions for the LT150 it has a ceiling front projection option. Maybe it is not properly explained in the instructions and all it does is just simply flip the image.


Huey is correct. He's an LT150 owner as am I. The image leaves the projector at a 17 deg. angle (image offset). There is NOTHING variable about the light path of the LT150 except image focus: no lens shift, no zoom, and no optical keystone correction. The menu controls for desktop/ceiling and front/rear projection are simply image flips on the chip. The image axis cannot be moved.


If the projector were on a table and moved away from the projection wall, the image would grow AND move up the wall; on the ceiling it would grow and move down the wall.


In the manual you will find a table listing image height, width, and offset from lens center for varying distances. The diagram illustrating the ceiling mount configuration assumes the projector is inverted. The manual explains it properly.


The behavior of the LT150 sounds like it's the deal breaker for you.


- Dieter
 

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This should clear up any confusion. Look at page 2 of this pdf file . It clearly shows why the projector has to be flipped upside down when it is ceiling mounted, unless you want to deal with keystone.
 

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Bill take a look at the picts under my signature, I have exactly what you describe. It's impossible to see the LT150 because of the ISCO lens placed in front, but the projector is upside down on the shelf. I bought little rubber feet from Home Depot which I placed underneath the projector to keep the intakes from being blocked. Since the shelf is fairly large and I am sitting under it, a partial hush box is created, blocking some of the fan noise.
 

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Ok.


I suppose since every other PJ I used had the feature I described I assumed this one would also.


How loud is this thing when upside down.
 

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2 PC fans going... small hair dryer :) It's hard to describe but it is annoying as it's higher pitch. Hush box is important unless you sit far from PJ (over 6 feet away).
 

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I just ceiling mounted my LT150 over the weekend. It's about 4 feet overhead of my seated position. I guess I don't find the noise all that annoying for a couple of reasons:

1) it is a constant level that you sort of "tune-out" after awhile

2) it is almost always drowned out by the audio (if you set the volume high enough!)
 

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I mounted my LT-150 on the ceiling last week. I expected the noise to drive me nuts until I had a hush box installed, but to my surprise it wasn't perceptively louder than it was before. The reason? Because before, it was set up about 3 feet from my ears, being on a small table between the two front chairs. Now it's on a 9' ceiling, so it's about six feet from my ears. Not only that, but before I was sitting beside the projector, and the sound emanated from the side. Now I'm directly under it, so the sound is dispersed a bit more before it gets to me.


It's still a bit annoying, but not as bad as I thought it would be. Once I get involved in a movie I forget it's there.
 

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The LT-150 fan kicks into high gear if it gets too hot. The fan also kicks into high gear when you do the vertical flip on the image, it's automatic.
 

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Since all projector input comes from HTPC, can't i hang the LT-150 from the ceiling, and use HTPC software to invert the image instead of having the projector do it. This way, the projector doesn't know its upside down. When the thermistor gets hot it will still speed up the fan, but if all is 'cool' the fan should stay at low speed.


Does anyone have any experiance with PC inverting software? I have seen some on a web site, I would have to look to find it again.


Marc
 

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Here we go again!!!


YOU HAVE TO INVERT LT150 DUE TO UPWARD VERTICAL SHIFT OF LT150. THIS IS NOT NEGOTIABLE !!!!


Inverting software will not fix the vertical shift of these PJs. It'll still shine on ceiling until you flip PJ then image will hit wall/screen.
 

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Quote:
Originally posted by Huey
Here we go again!!!


YOU HAVE TO INVERT LT150 DUE TO UPWARD VERTICAL SHIFT OF LT150. THIS IS NOT NEGOTIABLE !!!!


Inverting software will not fix the vertical shift of these PJs. It'll still shine on ceiling until you flip PJ then image will hit wall/screen.
Huey,


I think he means that you would still flip the PJ upside down but use HTPC software to invert the image and NOT the LT150 'ceiling' mode. I think Marc understands the image offset issue. He's doing this to attempt to avoid the fan speed-up that the ceiling mode brings on. That though may not be the best idea.


- Dieter
 
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