CurtPalme.com Home Theater Forum

[ecrabb]

Well, I've been thinking about doing this for years and yesterday the time came. I sold the 1271 last week and the buyer was coming to pick it up. I'm also WAY overdue to hang up my spanky clean G70.

Anyway, I screwed around with this a few weeks ago, then got busy and just got back to it yesterday too so all in all, I've probably spent around 4 hours or so messing around with this 'just for fun' stack. I know there's a few other guys with 12xx's that have talked about doing this, but to my knowledge, nobody has actually gotten around to doing it. Thought some you might enjoy hear about how it worked and looked. If you have questions, feel free to ask away.

The vitals
Projector 1: 1271
~3200 hours on the original 07mp tubes. Sony PT65 lenses. Pretty nice, clean machine from a local university surplus warehouse. This was my main projector and a pretty sharp clean machine. Ceiling mounted, fairly quiet, nice shape, well cared for. No longer in my possession as of 3pm Saturday! A nice local guy bought it to put in the HT he has yet to build.

Projector 2: 1272
~3800 hours on the chassis, unknown hours on the clean 07msp's that I retubed the machine with. HD8 lenses. Also from another state university, not quite as clean or as quiet as the 1271, I had to retube it because I bought it with desktop icon burn on it. If the 1271 is a 6 for sharpness, then this thing is just a 5.9 at worst, so very close - only very subtly different. It was set up in table-mount config on an old TV stand I built years ago - right behind my head, and slightly forward of the 1271.

Source:
Sony PS3 through HD Fury and output from two Extron 8x4 matrix switcher outputs

Cables:
Two 25' Python RGBHV snakes w/gold BNC's

Setup
Setup was about like I thought it would be - a pain in the ass. It isn't setting up a CRT x2; Rather, it's more like x3. Wired remotes would have helped some, but it was still confusing turning tubes on and off, setting specific things to adjust, etc. I set up the 1272 to match my 1271 because it was already set up. 30-40 minutes later, I had a pretty watchable picture. I could have spent a lot more time and gotten things better looking, but since this was just for fun, I didn't waste hours trying to tweak it to death. It looked good enough to play around with.

My Impressions
The first thing that was immediately noticeable was how much brighter the picture was (duh). That sounds stupid, but until you see two projectors, you don't realize the impact it will have. It was amazing actually. Leaving one at normal contrast and PIC MUTEing the other made it obvious how much brighter two projectors are than one. It's kind of mind-blowing. I could get used to the brightness - it really lit up the room. Bright whites from stuff like stage lights in a live concert - were really bright white - like you'd expect them to be. It gave the image a "reality" that one projector didn't have. This sounds weird, but it was like the stage lights were more like real stage lights rather than "video" of stage lights. The contrast between bright white and blacks really made stuff POP off the screen.

Even colors were more lively. Brighter, richer, more vibrant are all words I'd use to describe the difference between the stack and 1 projector. Skin took on a more alive feel, and one projector by comparison looked dull and flat.

Sharpness in a word, sucks. Even though I could turn contrast down to 40 on each and have a brighter pic than one at 60, it was still softer. The 12xx's just don't have the granularity to really nail convergence, and you have the compounding effect of TWO less-than-sharp projectors combined. Lots of times, while using zone to touch it up, one click either way would be just a little too far to take out a subtle red or green fringe. You could tell that running contrast lower made for a sharper pic on each machine, but you lose it again because you can't get both images laid perfectly over each other. Like I said, I probably could have done a little better job if I wanted to.

It's worth noting that there was one section of the screen that I just couldn't get to line up no matter what I did. It was roughly the 2/5 point from the left side. All corners were aligned, and the center was aligned, but a vertical section from top to bottom at roughly 1-3 feet from the left screen edge was 1/2" or more misaligned. There was obviously a difference in the linearity between the two machines and there was no way to dial it back out. If you were going to do this, you'd probably want to use identical machines with identical lenses, but even that would certainly be no guarantee.

Noise. It was incredible - just horrible. Two machines running - one inches from my head just sucked. It was literally a psychological relief to turn them off. Any music or quiet times are ruined because the noise - totally unworkable in practice. Double hush boxes would be mandatory. The two projectors (and my body) probably warmed the room at least 10-degrees in an hour. Not surprising when you consider that both machines together are drawing almost 10 amps or 1100w or so. You'd definitely have to vent them to another room as it would become stiflingly warm in no time - especially if you had a few more bodies. Either that, or you'd have to change the air in room constantly.

Conclusion
Just as I predicted, this just isn't worth serious consideration as anything more than good clean HT geek fun. The 'ol 12xx's are too noisy, put out too much heat, and just aren't stable enough to get them well converged or to try to keep them that way. One of these beasts is enough to worry about. You can see why stacking didn't become a reasonable option until newer more stable chassis came along. It was fun while I had the opportunity, though!

In fact, these old girls are so cheap now... If you have a couple 12xx's just sitting around, it's worth it just to see them running together on the same screen. All you need is a distribution amp, a strong back (or a good friend), and an afternoon with nothing else going on.

I always wanted to try a blend too, but VLC kept crashing and pissing me off back when was trying the panoramix plug-in. I gave up and never got back to it.

Photos


The two beasts fired up in the as-yet unfinished HT. G70 waiting in the other room.


Pretty well converged, except for that section on the left side that just wouldn't work.


Look ma, two shadows - and they're backwards! Notice the flip-flopped cyan/blue and red/yellow shadows.


Pretty nice grid - not sure why the mis-convergence didn't show up here, more.


There's that obvious non-linearity on the left side - really obvious here.


Both projectors on. Bright!


Simulated one projector on, one projector muted. I forgot to take a photo of only one on. Duh.

Hope you all enjoyed reading my ramblings about my little exercise.

SC

[AnalogRocks]

That looks like fun!

[AnalogRocks]

That looks like fun!

[Nashou66]

If you really really take the time to do a stack the brighter image will outweigh the softness. I thought i had a more film like image with the stack than my single set up ,However i should mention that I have a 12 foot screen and I sit 14 feet from the screen so i can see scan lines with one PJ put on my second marquee and woh ! Nice and bright better colors and the shadow detail is sooooo much better. So my opinion is a stack is better than a single of the same Projector.
But as SC states to do it well you need two projectors that you have the focus set up very very very well. I also found it better to have one projector with the blue sharp and the second defocused to get better whites overall.


Athanasios

[AnalogRocks]

[AnalogRocks]

[Nashou66]

No, I Have one PJ that was Professionally calibrated and is ceiling mounted (M8000) When i got my second working marquee it is the one that I am useing to test my mods on so I was constantly changing things on it and testing different settings to see how they looked. It was always in the stack and by trying different focusing techniques the one day i decide o see how sharp and image i could get with the blue focused. very sharp but a redish color. I defoucused it and tried the stack it looked good so for shits and giggles i focused it and tried it. The grey scale didnt go that far off to my eyes and the added sharpness of the whole stack just looked nicer to me so I left it that way. But now i added the HD144's and havnt put the stack together again. But If you have patiance and dont have the linareity probs I would stack. I am waiting to decide which of the TV-one scalers to use for a blend eventually so i really havent planed on stacking again. Like SC says it takes a long time to nail the convergence. And with marquee's trying to get two grids lined up with out introducing banding is very hard....but ti can be done.
And like SC says if you have two projectors, and even if they are not the same, you should try a stack for fun.


Athanasios

[kal]

Interesting exercise SC! Stacking is very much worth it if you have two good late model PJ's that don't drift. Not really worth it with the two that you have there as you've seen. If for no other reason than you can likely get more light out of a good 9" machine than two older 8" machines like yours.

Now two 9" machines - that's a treat. You can get the contrast reasonably low on both and with the 9" tubes they'll last easily into 30,000 hours on an average sized screen (say 8' wide). But then, stacking is all about lots of light and a big picture so most people woluld probably go 10' wide or more.

I've recently redone by greyscale very carefully and my light output can gone up dramatically. The difference in 'punch' like you mentioned is immediately obvious.

Kal

[kal]

Interesting exercise SC! Stacking is very much worth it if you have two good late model PJ's that don't drift. Not really worth it with the two that you have there as you've seen. If for no other reason than you can likely get more light out of a good 9" machine than two older 8" machines like yours.

Now two 9" machines - that's a treat. You can get the contrast reasonably low on both and with the 9" tubes they'll last easily into 30,000 hours on an average sized screen (say 8' wide). But then, stacking is all about lots of light and a big picture so most people woluld probably go 10' wide or more.

I've recently redone by greyscale very carefully and my light output can gone up dramatically. The difference in 'punch' like you mentioned is immediately obvious.

Kal

[Nashou66]

Kal's right when you have the grey scale nailed down that alone is a big improvement to a single PJ's light output or appearance of it. You get that PUNCH he talks about and a 3D look , colors just are more natural and shadow details come out. My calibrated set looks brighter than the uncalibrated one even though i have its contrast and brightness 10 clicks higher.

Athanasios

[Zebu Fellenz]

Very Nice,

I was going to do a stack with my old Marquee 8000 and G70 but the 8000 sold before I acquired the splitter to do the stack.

On the bright side this may have saved me from falling in love with the stack and all the extra setup, problems that would come with it.

Erik

[AnalogRocks]

Cross link time. We're re-discussing this here: http://www.curtpalme.com/forum/viewtopic.php?p=219120#219120

[AnalogRocks]

Cross link time. We're re-discussing this here: http://www.curtpalme.com/forum/viewtopic.php?p=219120#219120

[Clarence]

[ecrabb]

[Clarence]

[Jester]

What hardware would you need on the MINIMUM to do this?( has a second 1272 sitting in storage with the same hours as the one in the theater.) heck when I switched the one out for the lower hour one, I couldn't see the difference, they even had the same 4x3 wear, spooky im gonna have some time off this December and this is RIGHT up my alley for tinkering, and it leaves a working one in place to appease the movie buff in me


Scott

[ecrabb]

Scott, all you really need over what you probably already have is a distribution amp and a second cable to split the signal to both projectors.

I use a big Extron matrix switcher with multiple outputs:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190350411221

But all you need for a stack is this:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360209571984

$20 BIN!

Curt might have a few distribution amps laying around, too.

SC

[Jester]

ecrabb, thanks a lot that is really cheap. falls right in my budget