CurtPalme.com Home Theater Forum

[sj64]

Just curious,
I know that as the phosphor on a tube wears, it shows up as an increasingly browner area on the tube face. So does the wear affect the image by reducing the light output, or does it tint the light to a browner colour?

Wondering about this, because if it's the first case of reducing light output then, aside from being restricted to setting up inside the wear area, I could just boost the gain right. I'm becoming less concerned about tube life. The chassis seems to break down so much quicker and here in Australia spare parts are harder to come by.

There's a pretty worn set that I'm considering getting on the cheap. I might just crank it up light-wise and I'll be happy if it lasts me 2+ years.

'cheers
S.

[CRT_Ben]

There was a huge (one-sided) debate about this over on AVS when Perisoft got his first Barco. Go over there and search for "perisoft" and "toastybarco" or similar and you'll pull it up. The short answer is that you lose color as well as light so cranking it up doesn't solve the problem.

[Chuchuf]

Tube wear effects the picture in many ways.
First since tube wear among the different tubes isn't the same, it effects color balance and your ability to make white.
Next if the tube wear on individual tubes isn't perfectly even you will see the difference in tube wear on your picture.
And of course it effects overall light output.

Tubes are everything when it comes to CRT projectors.

Terry

[ecrabb]

This just came to mind: Cranking the brightness on worn CRT's to make them brighter is a little like just cranking up the volume on your amp to overcome the fact that your speakers have pillows taped over the drivers. In short, it won't work very well.

SC

[kal]

See here for pictures/explanations: http://www.curtpalme.com/TubeCondition.shtm

Kal

[kal]

See here for pictures/explanations: http://www.curtpalme.com/TubeCondition.shtm

Kal

[Fujifrontier]

what if you could burn the unused area to match the middle? :p

[perisoft]

Oh, fantastic.

Light output is decreased and tint is altered.

However, I found that this can be mitigated with filtering. Without a filter on the blue, if you photograph the tube face running full output, you'll see that the worn area has a big (actually green, not brown) cast, that shows up in a histogram:



Even if you turn up the brightness on this you still get lousy color. But if you put a rosco 65 theater gel on the tube, you get:



Note that the blue output is almost exactly the same, but that green tint is completely knocked out.

At the expense of driving the tube harder, you can extract some life out of a worn tube this way - it's no different than filtering the red and green to get the primaries right. In the case of a worn tube the color 'gets wrong' but you can correct it the same way.

[Fujifrontier]

an interesting perspective

[perisoft]

After I blind you with science you won't be ABLE to see the tube wear...

[ecrabb]

I still say it's like pillows on your speakers. Perisoft is just cranking it up to make it louder and using an EQ to try to even it out some. Pillow's still there and still sounds... not very good. Oh, and you're driving everything harder in the process, too.

Pillows.

SC

[perisoft]

ecrabb, technically you're right. But if you've got pillows over your speakers, better to turn everything down and use an EQ than not have a sound system at all!

Obviously if the wear is AWFUL it won't make a good image. But if you go from 1200 lumens to 700 (the equiv of 8" to 7") you can make it work and get reasonable colors.

I got a pretty good white out of the toastybarco before I upgraded the tubes. It didn't *pop*; it was 60% as bright as good tubes. But it was actual white and a helluvalot better than before.

[perisoft]

oh, and i'm not using the toastytubes anymore:

[zGman]

Gee whiz that's a nice improvement in tube condition!
What did you end up using for a screen?
And how's the rest of the room coming along?
We haven't heard much from you lately....
G

[perisoft]

Room has an upright piano in it, and other life stuff has intervened a bit. I've got it all planned out now, though. Fabric's up - brown suede on the walls and black in the equipment room; the gear is on shelving in there too. Couch will be resting on four subwoofers ( ) and a two level riser in front. Still need to fill / sand the ceiling and back wall - those will be dark dark dark grey.

Will have black carpet plus an oriental rug in the middle of the room, w/ heavy padding all around. Gotta figure out how to carpet the risers though; i'd like to do arcs on them but not sure how to wrap the carpet around...

All on a budget under 1k including the pj!

[perisoft]

In the end, experience with setup is everything in this game. It's almost as important as PJ quality, if not more!

For comparison's sake - here are some shots, two from the barco with the bad tubes, and one from a 4000-hour 1271 with nearly perfect tubes:







The first pic is from a really early setup of the barco with the lousy tubes. The second one is one with quite a bit more experience with setup. It has the horridly burned blue tube, but still, a big part of the lousy color there is from a lousy setup; at that point I only had ten or fifteen full setups under my belt and was a total n00b when it came to colors! It could have gotten quite a bit better, but the slight oddness to it would have stayed. But it's still sharp and not horrible to watch as your eyes tend to adjust to a given white balance if they have no external reference (something the color-anal guys seem to forget...).

The 1271 pic has vastly better color since I knew more about what was going on - plus it's color-filtered for better primaries, particularly reds. I was in LOVE with the color from the 1271, enough that I considered using it as my main PJ. But just a red gel on the 808 with better tubes makes a huge difference, and it CLOBBERS the 1271 in resolution and bandwidth, even with a fairly non-optimal astig and convergence setup. To wit, here's the retubed Barco:



All these are with upscaled SD DVD by the way, so even these small shots are higher resolution than the source material!

After all that I still haven't got the thing dialed in; I can probably get it fully resolving 1920x800p with some work. So... getting a really cheap PJ and screwing around is a good place to start. But PJs ARE really cheap now, or should be - that 1271 was free; I got it from some brooklyn artists' studio place that had it sitting around. So... just get an idea of values before you throw any cash at something.

Everybody told me to run away from the toastybarco, but the process taught me a ton and with patience I snagged newer tubes for next-to-nothing. So it was more than worth it. But unless it's free, stay away from a low-end PJ with bad tubes!

[Fujifrontier]

:hmm:

Instead of randomly twirling the G2 controls to get an approximate "white," i need to invest in a setup dvd...

[AnalogRocks]

[AnalogRocks]

[Dave Lister]

[Fujifrontier]

why do i need filters, my sony has snow white tubes

[AnalogRocks]

[AnalogRocks]