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Ohmess
Joined: 11 Sep 2008
Posts: 242
Location: Vienna, VA
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| Posted: Mon Sep 22, 2008 6:38 pm Post subject: 9500 Throw Distance |
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I am planning to upgrade my 8500 to a 9500. My 8500 is fixed to the ceiling and I have a 92" 16:9 screen.
What is the optimum distance for mounting the upgraded projector?
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Heywood Jablome
Joined: 12 Mar 2006
Posts: 1548
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| Posted: Mon Sep 22, 2008 7:22 pm Post subject: Re: 9500 Throw Distance |
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| Ohmess wrote: | I am planning to upgrade my 8500 to a 9500. My 8500 is fixed to the ceiling and I have a 92" 16:9 screen.
What is the optimum distance for mounting the upgraded projector? |
As always, depends on the lenses. You are going from AC to LC, so the TD may be substantially different. The shortest lenses are the 10Ls I believe. See: http://www.curtpalme.com/docs/ElectrohomeMarqueeUltra8500_8500LC_9500LC_User.pdf Appendix B (PDF page 87.)
Note that the best method is to just do it... Set your rasters appropriately then roll the PJ forward and back to fill your screen.
_________________
"Those countries which lag behind in industry, in the application of mechanics and technical chemistry, in the careful selection and utilization of natural products, where the respect for such activities does not permeate all classes of society, will unfailingly decline in prosperity. They will sink faster when neighbor states, with an energetic exchange between science and industry, go forward with renewed vitality."
-- Baron Alexander von Humboldt: 1769-1859
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Mon Sep 22, 2008 7:39 pm Post subject: |
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Hello
Try it out at floor level with all of your signals. It will be ten or fifteen percent farther back. Do not use the factory throw distance charts, they will have you too far away.
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Ohmess
Joined: 11 Sep 2008
Posts: 242
Location: Vienna, VA
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| Posted: Mon Sep 22, 2008 7:45 pm Post subject: |
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I thought Curt had advised others not to use the distances recommended by Marquee because the projector would be too far away? (Or maybe that was Tim?)
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Ohmess
Joined: 11 Sep 2008
Posts: 242
Location: Vienna, VA
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| Posted: Mon Sep 22, 2008 7:48 pm Post subject: |
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Thanks Tim -- what is my margin of error and which way should I compromise if differing inputs yield different results?
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Mon Sep 22, 2008 8:01 pm Post subject: |
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| Ohmess wrote: | | Thanks Tim -- what is my margin of error and which way should I compromise if differing inputs yield different results? |
You will get different results. Zero out the side blanking for all memories, set H size to 90, and which ever signal has the smallest width, set your throw to just fill the screen on that signal.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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Heywood Jablome
Joined: 12 Mar 2006
Posts: 1548
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| Posted: Mon Sep 22, 2008 10:44 pm Post subject: |
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I really gotta stop rapid-firing responses while working.
The slide-it-fore-and-aft method pre-supposes using either the maximum raster that is safe o the maximum that is practical... Safe depends on the PJ (NECs need extra safety margin, i.e. larger unused phosphor borders) while practical infers having to work within a burn.
Tim is absolutely right, the "official" mounting instructions are too conservative by 10% or more (NECs more so.)
_________________
"Those countries which lag behind in industry, in the application of mechanics and technical chemistry, in the careful selection and utilization of natural products, where the respect for such activities does not permeate all classes of society, will unfailingly decline in prosperity. They will sink faster when neighbor states, with an energetic exchange between science and industry, go forward with renewed vitality."
-- Baron Alexander von Humboldt: 1769-1859
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Tue Sep 23, 2008 12:36 am Post subject: |
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| Heywood Jablome wrote: |
Tim is absolutely right, the "official" mounting instructions are too conservative by 10% or more (NECs more so.)
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Guys!
I have inherited service responsibilities for six or seven Vidikron Visions here in the Phoenix area, and every freakin' one of them is sixteen or twenty inches too far from the screen. In two instances, holes were cut into the back wall of the room to accommodate the error, making servicing extremely difficult. H Size usually around 56 and the tube centers are cooked and the image is poor and lacks any sort of punch even at contrast of 70+. Truly a shame considering what those people gave $$$$$ for their equipment.
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Ohmess
Joined: 11 Sep 2008
Posts: 242
Location: Vienna, VA
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| Posted: Tue Sep 23, 2008 1:08 am Post subject: |
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56! Yikes! Talk them into letting you move the projectors forward.
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Tue Sep 23, 2008 2:49 am Post subject: |
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| Ohmess wrote: | | 56! Yikes! Talk them into letting you move the projectors forward. |
Too late now. The toasted areas will be too evident...and not just in all white scenes. Even in darker scenes the edges (unused phosphor) will be brighter and have better detail than the toasted centers. What a waste of money. And trying to explain the 'oops' to the client won't be an easy sell either. 6 times how much per tube? Ouch. A dozen doughnuts says they decide to go with <gak> digitals once repair to replacement costs are discussed.
Regarding the OP's question, I noticed nobody explained how to maximize raster, which is the first and arguably the most important step in a good setup. Not so much for the benefit of the OP necessarily but we have lurkers who may be making toast and not even know it. We tend to speak in acronyms and abuse of the alphabet because we've been at this hobby for a while. Hopefully they've done due diligence and studied before attempting a setup. <shrug> Just a thought.
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Greg
"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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kal
Forum Administrator
Joined: 06 Mar 2006
Posts: 18114
Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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| Posted: Tue Sep 23, 2008 3:28 am Post subject: Re: 9500 Throw Distance |
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| Ohmess wrote: | | What is the optimum distance for mounting the upgraded projector? |
For all CRT projectors the optimum throw distance the one that maximizes phosphor usage. Don't use math to figure it out, instead LOOK in the tubes and do it.
While following the manual for throw distance is always a good bet (and recommended for new users), to maximize tube life even further do the following steps:
- Put the projector on the cart or simply leave it on the floor so that you can move it.
- Display something that fills the screen entirely (like a grid test pattern).
- Using only the green (middle) tube, look into the tube and increase the image width on the tube face until it is around 1/8" to 1/4" from the edge of the white phosphor. Under no circumstances should you allow the image to go off of the white phosphor surface!
- Move the projector back and forth until the image fits your screen.
- THAT is the correct throw distance for optimal phosphor usage.
It'll usually be 5-8% closer than what the manual tell you because the manual throw instructions are conservative since they make you install blindly without even looking in the tubes at all.
Kal
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Ohmess
Joined: 11 Sep 2008
Posts: 242
Location: Vienna, VA
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| Posted: Tue Sep 23, 2008 1:46 pm Post subject: |
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This is very helpful guys.
I believe I have my current projector at 108" now. So, I'm thinking that right now my projector is too far away, but when I install the 9" tubes I should be pretty darn close.
Using kal's numbers, the factory distance is 5% to 8% too far away. So, if my factory calculations yielded a distance of 108", I should be set up at somewhere between 100" and 102.8." Now, using Tim's comment that the 9500 should be 10 to 15% farther back than the 8500, I get a distance of somewhere between 110 and 118." The low end of that range is pretty darn close to 108". Given that I installed the fixed mount at that distance, I hope the moving the projector on the floor test tells me I don't have to move the fixed mount. We'll see.
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