Again, I need some help . I just realized (after cutting the wood, of course) that the lamp (400w MH) would not fit "perfectly" inside. I wanted to place the lamp horizontally (Figure 1) but when I did, the filament (is that the word?) was way off. So I now I am thinking of placing it diagonally (Figure 2). I tried, it does fit but one question still remains -- is it ok to place your lamp diagonally? I mean, I really don't know if there is any difference, but since most of you have it horizontally I became really suspicious... Any help would be GREATLY appreciated!

I tried it that way, it will work, but beware, you will have 2 fairly well lit corners, and 2 relatively darker corners.

I found it to be easy enough to do a horizontal mount. Vertical would be best though, even upside-down might work.

Why is that? I always thought that the proper and best way is horizontally... but if you say so, I will probably mount it vertically.

Vertical is supposed to light the Lcd better because of the way the arc is shaped.

But the lamp needs to be burned in vertically if that is the permanent way it will be mounted.

Hey jonjandran(or anyone who knows I suppose), does anyone know for sure how much of a difference that makes, which position it is burned in?

Let's see, I think Dazzla/Elken/Arizonavideo/Simul8r one of them (maybe) did a test with the lamp in the vertical and horizontal position. With the lamp vertical the arc spread across the Lcd more evenly creating higher lumens.

I'll see if I can find the thread.

did anyone find it?

Got it
http://www.lumenlab.com/forums/index.php?s...st&p=113298

You are the man! Thanks for all the info.

Also, fwiw, diagonal is the method used for the prototype in the guide, basically for the reasons you were going to try it.
I'd prefer it to be vertical, but with certain bulbs that have an approximate distance from the bottom of the mogul base to the center of the arc chamber of about 7.5 inches, that can make for a fairly tall box.

Oh sorry jon, I meant does it matter if the bulb is burned in horizontally/vertically, and then used in a different orientation

I can see how I was misunderstood; I am indeed already a believer in the Vertical Way-even though I don't have my own bulb vertical...

Yes it matters. Most of the time it won't work. The arc won't be stable and it will jump a LOT.

You have to run it the way it was burned in.

Awww JJ, you beat me to it

What jonjandran said is true. The manufacturers for each lamp state how they should be burned in their specifications otherwise you may expect short life of the arc or lamp explosion. I myself have taken some lamps including an Osram double ended 400w lamp that should be burned horizontally and tied each of them in vertically for several hours (approximate 6 hrs straight) but with full active cooling. I suspect heat is the major culprit.

The reason some of these lamp's arcs are not steady standing vertically is because of their arc's length. I suspect something like Jacob's ladder, the wider the arc the more twirling of the stream....well maybe not because in one particular case though using a PlusRite 6500k 400w bulb from mikyd I noticed the lamp burned steadier 'standing' straight up as opposed to straight down and I beleive it had about a 40mm arc. I'll even go out on a limb and suggest that one end of the arc (top end) is much brighter then the other when the arc is placed vertically. And when the lamp is placed horizontally the arc 'curves' up. But in most cases I found in a horizontal build the lamp burns brighter standing up veritcally. A 6% brightness will be also loss when including a front surface (fs) mirror in a fold.

In the link of my experiment of vertically vs horizontal placed lamps, as JJ pointed out, the arc chamber within our street lamps are long and cylindrical making it difficult to fit through our triplets (more so with the standard smaller triplet) when projecting as arizonavideo explains. The better pro triplet or the lesser larger 18" opaques work more efficiently with the longer arc lamps. The cylindrical arc chamber creates a brighter 'butterfly' effect that when placed horizontally illuminates mostly the top and bottom of the lcd. But it is the length of the lcd that is the longest therefore when placing the arc vertically the 'wings' of the 'butterfly' illuminate the lcd lengthwise better. This more so when incorporating a precondenser in the light engine.

Just remember, when building horizontally the lamp works better standing vertically. If building vertically then shift the horizontal placed lamp 90 degrees to the lcd.

Hope this explains my spill and thoery on the subject but if there are any others then feel free to join in.

Regards