Film-Tech Forum ARCHIVE: Christie CDXL-30 and -20 lamp issue, anyone else?

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Posted by David Zylstra (Member # 4230) on 06-13-2008, 02:46 PM:

Over the past several months I have been tracking seveal Christie CDXL/CXL lamp performance in our digital projectors.

So far both the CDXL-30 and CDXL-20 have been removed from service early due to low light output.

The facts:
All projectors are Christie CP2000H
CDXL-20 - when installed the max onscreen was 18FL (at 110% power), 14FL was initially reached with 90% power, after the 500 hour mark the lamp was running at max power (110%) and only hitting 12FL, now at the 950 mark the lamp is only able to hit 9FL. When I calculate the lumen output this lamp started at just over a max of 8,000 lumens and now at only 40% of its warranty life the max is just over 4,000 lumens (this lamp is estimated at 9,000 lumens in our projectors). This same drop has been noted with 2 CDXL-20 lamps in the same projector, CFM is running at just about 600 (the required minimum). The next step is to verify this drop with another CDXL-20 in a different projector.
CDXL-30 - when installed the max was hitting 24FL, this lamp saw a small, quick drop and then maintained 14FL at 93% for 600 hours, then stabilized at 100% for 300 more hours, now at 1,000 hours (70% of warranty life) the lumen output has dropped 60% (when installed 13,500 and now only 5,000). This same drop has been noted with 2 lamps in 2 separate projectors. Cooling for both has been verified at a minimum of 600CFM each.

I am gathering data from other lamp sizes, but so far none of those have become unusable.

A few notes:
The Christie projectors report power in % of a given lamp size's rated amperage - i.e. you tell it the lamp is a 2000 watt model and internally it knows the proper amperage range.
All my data has been emailed periodically to many departments at Christie so they are aware of my results, so far no response on why these 2 lamps seem to be poor performers.
So far the other lamps are performing well and have not seen as significant a drop as the above 2 lamps (CXL-30, CXL-45, CDXL-45 and CDXL-60)
I'm using a Sekonic L758Cine (similar to the ones issued to Christie techs) - margin of error on the readings is +/- .5FL (yes, not the best but it works).
The idea of my data is NOT to prove with accuracy the actual lumens of each lamp, but rather to show what the drop in output will be so I can properly size lamps for each screen (and the manufacturer claims there is no similar data available).
A CXL- type lamp in the same projectors as the above lamps maintains output much better over the life of the lamp (so there can't be too much wrong with the projectors in question).

To answer the obvious question - yes, the autofocus procedure has been run periodically on each lamp.

I'm curious if anyone has seen anything similar with these 2 lamps? With these lamps in other digital projectors? Anyone tried them in 35mm?

I apologize for such a long post.

Posted by Brad Miller (Member # 2) on 06-13-2008, 03:23 PM:

I have. I tried pulling a CXL-60 and replaced it with a CDXL-45. So far the light output was pretty much identical. However I did try pulling a CXL-60 from another screen and replaced it with a CDXL-60 and didn't see any noticeable light improvement.

Maybe I just happened on a bad CDXL-60 bulb, but unless Christie is willing to sell me another at the CXL-60 price, I don't think I will bother for any more CDXL-60s in the future. The jury is still out on the CDXL-45.

Posted by David Zylstra (Member # 4230) on 06-13-2008, 03:43 PM:

So far my CDXL-60 tests (3 in 2 different digital projectors) have worked well, but I do find it to only be marginally better than the CXL-60 - the estimated lumen output is 20,000 for the CDXL-60 and 18,000 for the CXL-60 (in the CP2000H) . . . . . . I have found that the CDXL-60 output seems to vary lamp to lamp - i.e. on one screen some would hit 16FL at 110% where others would only hit 14FL (by the math about a 2,000 lumen difference). In our case the extra few lumens from the CDXL helped to hit 14FL with the single lens solution.

I echo your sentiment on the price - Christie originally installed CXLs in all our digitals so we have continued to use them, other chains got CDXLs from the start and told by some the CDXL was the only lamp to use.

Posted by Steve Guttag (Member # 268) on 06-13-2008, 09:16 PM:

I've been doing quit a bit of research myself on xenon lamps (including the CDXL line).

In some ways, xenon lamps behave a lot like LEDs...if you run them hard they will decrease in lumen output faster. Thus, if you start a lamp at the bottom of its range, it is likely to last a lot longer. Furthermore, as the lamp ages and you increase the current, it will progressively go down.

However, all xenon lamps experience a degree of "burn back" which normally occurs within the first 100-hours. It is TYPICAL of most xenon lamps to drop 20% of their light output within the first 100-hours..

I have certainly tested lamps that were faster than this and certainly tested lamps that were slower...but on average, without knowing the characteristics of a specific model lamp, 20% decrease in the first 100 hours should be expected. Thus, if you have a lamp running at 80% of its rated power at the get-go...it will be up to 96% by 100-hours (20% of 80%).

Typically, after the initial burn back you will get a much more gradual fall off.

I have seen some lamps where the light increased into its life! As the arc changes due to the electrodes wearing, how that arc works with the reflector and lens optics can improve or degrade.

I do not have a lot of experience with the CDXL-20 yet though I have a projector using it now...it is operating towards the bottom of its operating range though.

Christie has been pretty up-front with their CDXL specs. The CDXL-20 SHOULD get about 26% more light than the CXL-20. So, if the CXL-20 got you 14fL...the CDXL-20 should send you up to 17.64fL. Some may not see that as too big a deal. However, you will run the lamp at 14fL...thus turn the current down...this will start the CDXL on what should be a longer life in the same application as you are running it less hard and also spending less money on electricity doing so (26%).

There are similar numbers for the CDXL-30 over the CXL-30 (those I have not tested yet).

The CDXL-45 is another animal all together. The performance gain on that lamp is 38%!!! That is huge. That is the difference between 11.6fL and 16fL...just by changing the lamp!

This is a lamp I have been doing some extensive testing on. It looks to be a VERY stable lamp with a lower than normal burn-back and an even slower than normal decay. Thus it is brighter and more stable that most any alternative it is wattage range.

Now look at the CDXL-60. It is listed as only a 11% gain. So, if you had 14fL...it will only bring you up to 15.54fL. Some might not see that as such a big deal for the extra expense.

Another thing to consider is that as the arc gets larger on the larger lamps, the actual light efficientcy goes down as the aperture (or imager) puts restrictions on efficientcy. Thus a 6KW lamp generally does not bring that much more light than a 4KW lamp in a 35mm application though it is likey to improve a 70mm application. The same would hold true for DLP imagers...though I don't know of any of the .98" DLPs that will support a 6KW...most likely for this reason (not to mention they are typically smaller machines and would need more venting).

As for lamps in general....you should always have at least 30% more power available to you when the lamp is new if you expect to have the light remain good over a reasonable period of time...if you are starting at 90% of rated power...you will likey not have good light for too long....film or digital.

It sounds to me like you need to go to 3KW in your 2KW applications and 4.5KW in your 3KW applications. While the lamps may cost more at the onset...you will likely have well-lit pictures for much longer...which might end up being less costly as the $$/hour of lamp life will actually be less.

Steve

Posted by David Zylstra (Member # 4230) on 06-13-2008, 10:22 PM:

Here is "as advertised":
A CDXL-20 can be used instead of a CXL-30
A CDXL-30 can be used instead of a CXL-45
A CDXL-45 can be used instead of a CXL-60

I am testing the above for validity.

The screen in question with the CDXL-20 normally uses a CXL-30 and that lamp can maintain near 14FL over it's life, BUT the CDXL-20 cannot. Also, by my calculation the CDXL-30 after only 1,000 hours cannot even properly light the screen that currently has the CDXL-20.

Here is the estimated lumen output of each lamp type in the CP2000H:
CXL-30 - 8500
CDXL-20 - 9000
CXL-45 - 12,000
CDXL-30 - 13,600
CXL-60 - 18,000
CDXL-45 - 18,700
CDXL-60 - 20,000

So from the above estimations the CDXL lamps **should** be able to replace the next higher CXL lamp size.

I was told that because of the .98" chip's heat limitation the largest lamp possible is a 2kw - hence the CDXL-20SD that is supposed to output 12,000 lumens with the M projector.

Posted by Steve Guttag (Member # 268) on 06-13-2008, 10:48 PM:

It seems that you CAN use a smaller size lamp...if your only criteria is to use it a brief period of time. The fact remains, that smaller lamp is going to run out of headroom much sooner. Again, if you don't have at least 30% of the lamp's rated power in reserve when it is new...you will likely not get a long life out of it.

Steve

Posted by David Zylstra (Member # 4230) on 06-14-2008, 10:42 AM:

To get back on point - my observed drop on the CDXL-20/30 is much more significant than the CXL-30/45 over the same time period, if the CDXL rolled off similar to the CXL then this lamp would work perfectly fine on these screens . . . . . . I'm curious about other people's experience with these lamps and if anyone else has noticed similar huge drops in light output.

I just want to confirm the claimed performance of the CDXL line (and the claim of a CDXL-20 replacing a CXL-30, a CDXL-30 replacing a CXL-45, etc).

Here's the scenario with the CDXL-30: installed at 83% power with 14FL onscreen, within 100 hours was at 91% for 14FL, 600-900 hours the power needed to be creeped up to 110% and after this point it could only hit 12FL, now at 1,000 hours it can only hit 9-10FL (and has been changed) -- so I'm assuming that starting at 83% there should have been enough headroom to maintain 14FL at least over the 1440hr warranty life.

Posted by Steve Guttag (Member # 268) on 06-14-2008, 06:53 PM:

David, I was trying to be on topic.

With a lamp running at 83% power...a typical lamp will be down such that it is running at 99% power at 100-hours to hold the same light...the CDXL, by your numbers, is only down to 91%...it is actually a lesser burn-back.

The marketing ploy about replacing a larger lamp with a more efficient smaller lamp is true in the sense that smaller lamp will be brighter at the start..BUT it is nearly at the maximum of its range so it won't appear to last as long.

What you didn't post (or I missed) is what the CXL-30 you had was running at (percentage of its rating at the start). Only in that way can you judge if the CDXL is really dropping faster.

The only lamp that truely compares favorably to the next higher lamp is the CDXL-45. It is 38% brighter than the CXL-45 and thus, is like putting a CXL-60 in but with 4500-watt electricity (and longevity). The 18% or so improvements that the CDXL lamps give you in the 2-3K range (or 6K) is not going to allow you to truely drop a lamp size. However, by using the CDXL line instead of the CXL line but with the same wattage, should give you a lower starting current AND a more stable and longer lasting lamp by merely starting them out at a lower current.

Steve

Posted by David Zylstra (Member # 4230) on 06-14-2008, 09:02 PM:

The comparison for the CDXL-30 test is a CXL-45 (the normal lamp in that test auditorium) - it usually starts around 92-95% power and maintains well.

The CXL-30 and CDXL-20 tests are on the same size screen - both of these lamps started at 90% - the CXL-30 for the same number of hours is only running at about 103% and still hitting 14FL, other CXL-30 lamps at the end of their life (warranty +30% in our case) are hitting 11 or 12FL at 110%.

Since the CDXL-20 is spec'd at slightly higher outut than the CXL-30 so you would think it would start at a lower wattage than the CXL normally would - in my case it started about the same.

So what's not favorable of 13,000 lumens for the CDXL-30 compared to 12,000 for CXL-45? logic says it should work just like the CDXL-45 for CXL-60 swap.

So from your perspective a better test would be to start each lamp a 75% and maintain the resulting luminance over it's life (too bad no one at Christie made that suggestion when my desire for these tests went through the ranks) . . . . . I'll try that on the next rotation if I choose to try another CDXL-20 or -30 (and I will if more people come out saying they have not seen the same issues I have).

On the off topic comment - I was referring to how it seemed we were drifting to lamp size recommendations for my screens instead of real life experiences with the CDXL lamps, I do understand where you are coming from in trying to understand the exact situation.

Posted by Ron Curran (Member # 3631) on 06-14-2008, 11:14 PM:

how many postsers does it take to change a light bulb?

Posted by Mark Gulbrandsen (Member # 72) on 06-16-2008, 02:26 AM:

Good one Ron!

quote: Steve Guttag
In some ways, xenon lamps behave a lot like LEDs...if you run them hard they will decrease in lumen output faster. Thus, if you start a lamp at the bottom of its range, it is likely to last a lot longer. Furthermore, as the lamp ages and you increase the current, it will progressively go down.

quote: Steve Guttag
if you are starting at 90% of rated power...you will likey not have good light for too long....film or digital.

Lets not leave the CDXLxxSD lamps out of the equation either. The latter statement above may not hod true for these lamps... These lamps are made to be run at maximum rated power right off the bat and are supposed to maintain said lumens for the rated life (hours) of the lamp.

Mark

Posted by David Zylstra (Member # 4230) on 06-16-2008, 07:32 AM:

I've been waiting for pricing on the SD models from our dealer . . . . . they have CDXL-30SD pricing but they are still waiting for CDXL-20SD (AFAIK they are still waiting for Christie to respond to their inquiry - when the CDXLs came out we had the same trouble getting prices and availability).

If the pricing is close to CDXL pricing I will definitly test those as well. (and I'm anxious to hear anyone else's experiences with them as well)

Posted by Steve Guttag (Member # 268) on 06-16-2008, 08:32 AM:

The SD models were not mentioned and I don't have personal experience with them.

Note, my experience with the CDXL lamps is that they do not have as much burn-back as more traditional CXL lamps. In fact, the CDXL-45 just doesn't age much at all!

I don't think it was a wise move to promote the CDXL's as having the ability to reduce one's lamp size...as by retaining the same lamp size, one increases their headroom for lamp aging as well as one can lower their current and save on electricity. Again, the exception being the CDXL-45 versus the CXL-60...the CDXL-45 even goes up to 155A instead of 150A. Note, the CDXL-30 goes to 120A rather than 110A of the CXL-30.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 06-16-2008, 08:49 AM:

Steve,

While a couple of them can certainly give you alot more light under certain circumstances in certain lamphouses/consoles I definately agree with what you say about the headroom thing. I will be testing the CDXL60SD in the large format system starting next week but it'll take a while to tell whats going on....
Rated life on these lamps is shorter so also be sure to take that into account.. not just the pricing between the CDXL line.
Mark

Posted by Monte L Fullmer (Member # 2797) on 07-04-2008, 01:46 PM:

I want to shift this over to film usage for a minute here: Would I benefit if a CDXL-20R (if this version is available) be used in a X-90 console that is presently burning a 25SC bulb?

At present, we can't keep these 25SC bulb in operation close to warranty (at 1500hrs), and if we can go over warranty, they fail close to 2000 hrs.

What is the warranty on these "DXL" bulbs anywhos? - lower than the standard CXL bulbs?

In the past, we could easilly get over 3000 hrs on these 25SC in the past, thus what happened: did Ushio/Christie reduced the quality of this line of bulb, or do I have a rectifier condition here?

thx-Monte

Posted by David Zylstra (Member # 4230) on 07-04-2008, 02:46 PM:

Theoretically it could - although the CDXL-20's cathode end is the same size as a CXL-30 so beyond the anode cable that is the only question on fit (maybe the -25SC is already the same size).

The warranty on the CDXL-20 is the same as CXL-20 - 1200hrs full and 2400hrs pro-rated.

Cost differential from CXL-20 to CDXL-20 is at least 50% higher, but the differential between CXL-30 and CDXL-20 is almost a wash (but then factor in the higher warranty and you come out way ahead).

Christie is touting a "CDXL lamp down program" on their website.

So far I am not completely convinced the CDXL-20 would outperform a CXL-30 in terms of light output over the life of the lamp.

Not sure on the current -25SC lamp life though since we don't use those.

Posted by Steve Guttag (Member # 268) on 07-04-2008, 05:10 PM:

Monte,

If there is an equivalent CDXL-20 for the CXL-20SC (not the R)...it would be called the CXL-20SCH. I don't know if it in fact exists.

The CXL-20SC, CXL-25SC and CXL-30SC all use the same cathode pin and should be physically exchangable.

I would look into your exhaust and ensure you are pulling out enough. Most people try to avoid the 2500-watt lamps as they are normally too big a lamp for their package size. They are notiorus for not being the best in the long life department.

Another solution for you Monte is to use CXL-30SCs and only operate them like 2500s. The cost is pretty close (less than $100 difference) and the life expectancy is the same...just the 3K is a little bigger to dissapate the heat. That is, you are likely to get longer life out of the 3K running like a 2500.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 07-04-2008, 05:31 PM:

quote: Steve Guttag
If there is an equivalent CDXL-20 for the CXL-20SC (not the R)...it would be called the CXL-20SCH. I don't know if it in fact exists.

There is a lamp along this line for the M projector. It obviously won't be available till the M projector is available around the end of this month.

Mark

Posted by Steve Guttag (Member # 268) on 07-04-2008, 10:18 PM:

Christie is going to use a non "HTP" style lamp in their projector? No way.

The "H" in the name that I listed denotes the CDXL lamp (high-output) but in a more traditional package as used by NON Christie lamphouses. So, CXL-20SCH would look like a CDXL-20 in the envelope area but would look identical to the CXL-20SC at the stems.

Again, I don't know if they have a CXL-20SCH but if they do, that would be the letters they would use based on my other lamp testing.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 07-05-2008, 09:34 AM:

Steve,

Its a short 2kw lamp and pretty small overall, I have not seen the ends of the lamp yet. Christie has been working with a no compromise attitude with Digital projectors so nothing would surprise me. There are even a number of very valid reasons for them still using the 1.2" dmd's in the 2000 and ZX although the M will use the .98" dmd's.

Mark