[mflaster]

I've read a lot about the mods that Thumper has done for other DLP projectors, and so I was very interested to see what he could do for mine. I own the Viewsonic 1030, which is a clone of the Davis DLX650 (XGA DLP). He had never worked on my type of projector, but he was very happy to have me as a guinea pig! My biggest issues were a big green shift due to Revision 'L' software (to fix tearing), a big halo, and I was interested in what he could do for the black level and color saturation. Also, though the contrast seemed good, having it tweaked and improved can only be considered a Good Thing.


First, a little background. Due to some warranty issues, before my projector was replaced, I was able to compare it side by side to the Viewsonic 1035, which they considered an "upgrade". It's an XGA LCD, rated 1,000 lumens, whereas mine is only rated at 675 lumens. It was absolutely no contest. The DLP blew away the LCD. Even though it was much dimmer, in my relatively dark basement, it was plenty bright, and the contrast and crispness was just *so* much better. I showed it to my wife to get a 2nd opinion, and she thought I was kidding when I asked her which she liked better, the difference was so extreme.


Anyway, I'm always interested in making my projector all it can be (especially if it's someone else doing the tweaking), so I sent it off to Thumper. Some interesting numbers from him. Turns out my projector puts out 350 real lumens (which he said is inline with a quoted 675 lumen projector), and its black level was 3 lumens (!). So it's (real) contrast was just over 100:1! Very surprising, because it looked very good to me, and I've seen other high end projectors (though not next to mine). He said that the clear section accounted for almost 50% of the brightness(!), and the green accounted for 1/2 of the remaining (instead of 1/3 if all colors were equal).


I'll skip all the intermediate steps, but what he ended up doing was putting a pure green filter on the green section of the color wheel. This might seem odd, but essentially it served to block the "almost-green" light that was making it through that section. He toyed with the idea of putting a color correcting dark color on the clear section, but he ended up just going with black. Whereas blocking the clear section should have lost about 45% of the lumens, bringing it to 193 lumens, he was able to "refocus the light path" and assorted other magic to increase the lumens by about 20% to 225 lumens. And amazingly, the black level was cut by more than a factor of 3! Below 1, which is the lowest his light meter would measure. So, the contrast about tripled, to probably somewhere in the 300:1 - 400:1 range! He said the halo was reduced by about 75%.


Now, on to *my* impressions, once I got the projector back. WOW! would be my summary. I had to do a lot of tweaking, as the output characteristics of the projector changed a lot. Interestingly enough, I had to *decrease* brightness. But after doing lots of tweaking (and still more to do), the colors look terrific. Very rich, very saturated. The contrast is significantly better - very 3D. The brightness decrease is not an issue. Even with enough ambient light to see to walk around, the picture is still fine. The blacks are *really* black - I now know what I was missing. OK, I'm sure CRT's are blacker, but it looks inky to me. And the halo is practically gone. I mean, I can still see a faint shadow if I put my hand in the halo area - but I used to be able to put on shadow plays... http://www.avsforum.com/ubb/smile.gif


Also, the green shift, to my eyes, is much better. Thumper decided to not try to completely eliminate it, as I would have had to give up some more lumens, and I have an HTPC, so I can adjust in software. But whereas in WinDVD I used to move the two color sliders 2 clicks to the right each, now I just move one of them 1 click to the right. So I guess it's 75% better! http://www.avsforum.com/ubb/smile.gif


Thumper is a great guy to work with. Very professional. I get the impression that these mods are of the highest quality - although he points out that this is probably the first time anyone has ever had a color-corrected color wheel... Uh oh!!! http://www.avsforum.com/ubb/smile.gif


I recommend it hightly!! 2 thumbs up!


Mike



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[Robert Clark]

Awwesome, Mike.


I'm very interested in seeing if he can get rid of the greens. How much is he going to charge for the mod? Thumper, I'd love to have some details!

If I have no more greens, I'll be as happy as those who got the LT150 for $1700...

(There. I included my now mandatory, contractully obligated mention of the LT150 in every post).


Robert


------------------

Robert Clark

See our home theater (with very poor quality pics!)
http://albums.photopoint.com/j/Album...874&a=12744078


[This message has been edited by Robert Clark (edited 07-30-2001).]

 

[mflaster]

(I should have put LT150 in my subject or else no one will read the post http://www.avsforum.com/ubb/smile.gif )


If you're more interested in color correction, I think there's a lot that Thumper can do. Instead of letting all the pure green light through, he could put on a darker green filter, to block some of it.


And if you don't want to lose all you lumens, he could probably put something like a dark blue-gray on your clear section. Then you'd keep some of your lumens, and you'd get a little more blue light, which I think would help balance the colors better.


But Robert, you have an HTPC. Do you not want to tweak it in software? Do you have a Geforce video card, or Radeon? My Geforce lets me change the "hue angle", whatever that means, in addition to the WinDVD controls, for tweaking color.


Mike





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[ghibliss]

Because your Davis projector does not have a flashable eeprom to change the gamma look-up table you create additional problems with the Thumperized unit that may not be properly addressed! By reducing the Black Level output of your projector you now need to recalibrate the contrast and brightness settings of the projector against a Pluge pattern. This is easily done but the next step is not easily fixed. By changing the contrast and brightness settings you have skewed the entire Gray scale and will have a non linear performing projector. The midrange should now be significantly out of range and will have no way of being recalibrated.


I have Davis factory software which allows one to recalibrate the gamma look-up table. The caveat with this software is that since there is no flash memory eeprom in the Davis projector the new look-up table is active only until you turn the projector off. The only way that this could be circumvented would be to have a dongle made (hard coded key)that contained the file for the projector and was physically attached to the projector so that it would automatically boot up the file when the projector was in use.

 

[mflaster]

Where on Avia is the Pluge pattern? I'd be happy to take a look.


Mike



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[ghibliss]

The Pluge pattern is called a Needle Pulse pattern on the AVIA disk. What you will find when you run this pattern through your projector and adjust the display properly is a non-linear tracking Gray scale. The problem is caused by resetting the contrast and brightness without any change to the gamma look-up table. Another reason that effects the Gray scale a great deal is the Halogen lamp used in the projector. This lamp has a measured color shift of close to 2,000 degrees from new to approximately 100 hours of use.


I was at the Davis factory in Drammen, Norway in April and measured the projectors at that time. The lamps drop a significant amount of the Red output in a short time frame at the beginning of their life cycle. As a result a gamma look-up table properly designed for use at 0 hours will be radically different from one accurately calibrated at 100 hours.


The lamp stabilizes in its output curve at this point and does not change substantially to the end of its life cycle. The light output will decline gradually but will not change the color balance (spectral output)significantly. It is truly unfortunate that most LCD/DLP projector manufacturers do not design the gamma look-up tables for a lamp at the point in its life cycle that it has stabilized at which represents the majority of its useful life.


The Davis OSD menu has no provision for adjusting White Balance so you are really stuck with what you have. The Gray scale of the Davis projector with a new lamp is generally as good as you will see on any projector made. I measured it to be very close to 6500K on several different models while in Norway with new lamps.




[This message has been edited by ghibliss (edited 07-30-2001).]

 

[Robert Clark]

I am definitely more interested in color correction than black level adjustment. As far as my HTPC, I have a Radeon (and used to have a Geforce) and the only color correction that I am aware of affects desktop color but has no apparent effect on Dscaler.

If someone can show what I am doing wrong I would be most grateful...


(Oops, I forgot...LT150, LT150, LT150...)

Robert

Quote:

Originally posted by mflaster: (I should have put LT150 in my subject or else no one will read the post http://www.avsforum.com/ubb/smile.gif ) If you're more interested in color correction, I think there's a lot that Thumper can do. Instead of letting all the pure green light through, he could put on a darker green filter, to block some of it. And if you don't want to lose all you lumens, he could probably put something like a dark blue-gray on your clear section. Then you'd keep some of your lumens, and you'd get a little more blue light, which I think would help balance the colors better. But Robert, you have an HTPC. Do you not want to tweak it in software? Do you have a Geforce video card, or Radeon? My Geforce lets me change the "hue angle", whatever that means, in addition to the WinDVD controls, for tweaking color. Mike

------------------

Robert Clark

See our home theater (with very poor quality pics!)
http://albums.photopoint.com/j/Album...874&a=12744078


[This message has been edited by Robert Clark (edited 07-30-2001).]


[This message has been edited by Robert Clark (edited 07-30-2001).]

 

[mflaster]

Quote:

Originally posted by Robert Clark: I have a Radeon (and used to have a Geforce) and the only color correction that I am aware of affects desktop color but has no apparant effect on Dscaler.

My understanding is that this is 1 area where the GeForce is better than the Radeon. Under control panel -> display -> settings -> advanced -> super advanced (I forgot the last panel), there's an "overlay" tab, and you can tweak the overlay for the GeForce. My understanding is that the Radeon doesn't have that, but I don't have it, I wouldn't know.


You know, dScaler has some tweaking options too, I just remember brightness, but that wasn't the only one.


Mike




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[Thumper]

I would like to fill in a few of the gaps for those wondering “whats up†with the mods performed on Mike’s projector.


Mike asked me to take a look at his unit and he also provided a list of problems and shortcomings. It seemed like a challenge worthy of the time required to investigate http://www.avsforum.com/ubb/smile.gif It was our intent to try to address each problem together to the best possible extent and within a reasonable timeframe. The result was a good solution for Mike and his situation, which may or may not be for others depending on their requirements.


The following is derived from some of the communications between Mike and myself. First I'll outline the initial impressions/problems and then describe the modifications performed to address each. Please note the green shift was not high on his list as his video card was able to counteract the shift to a good degree:


1. The Green Shift (the "greenies").


2. Weak primaries with "washed out" colors, particularly at brighter levels.


3. Some light leakage around the image and


4. A generally poor overall contrast ratio.


Now on to the mods:


I won’t dive into the software revision "fixes" and the resulting green shift issue as this has been thoroughly discussed before. I still firmly believe the best fix is in the software realm but that may not happen now with the current status of the projector line and the effort required to affect a proper, hassle-free, permanently loaded fix using the gamma table(s).


The green shift was significantly reduced with the addition of a green filter (a LEE polyester filter) to the color-wheel green sector only. Fourteen different filters were applied in a series of tests to find the one with the best combination of color filtering and primary attenuation. It is not in the path of the red or blue sectors and does not affect the yields of those two remaining primaries, as an overall color correction filter will. The filter is applied to the backside of the wheel - basically between the wheel and the DMD chip and not on the side of the wheel facing towards the lamp. This is a more difficult install but it almost completely eliminates the Infrared and UV that the filter would be subjected to if installed on the lamp side. The filter (and wheel) operate at about 130-150 degrees (F). This should result in a long and stable life for the filter, which is rated at about 450+- degrees. This also reduces the total amount of light thru the filter because the light is filtered first by the green dichroic on the wheel before reaching the filter and it is time-shared with the other segments in the light beam. This will significantly reduce fading of the filter over time as it is only refiltering and purifying green light to begin with. The optically clear adhesive used appears to be very stable and secure. As this is the first of its kind, only long-term use will confirm the stability of the adhesive and filter materials (This is where Mike comes in http://www.avsforum.com/ubb/wink.gif FYI, all adhesives and materials used in the project are reversible and removable. FYI, the wheel was rebalanced on the opposing side with an adhesive based counterweight (not a particularly easy task on this color-wheel design).


In this unit, after the clear section, the green primary is the greatest contributor to overall brightness. The filter applied was chosen as a compromise between color correction and loss of green channel brightness. It reduces the green sector yield by about 20% giving a better balance between the three primaries (acting as a single primary attenuator). At the same time, the filter also removes a very large portion of yellow from the green sector yield, enabling deeper, richer greens. A deeper/stronger green filter could have been used to more fully correct the imbalance in the primaries, but IMO that would have reduced the brightness too much. As a side note, if you run a signal into the S-video or video input now you would notice the image is quite red, that in essence, signifies the adjustment made by the filter to reduce the green primary output (In other words the filter is only for those who will use the VGA input, not S-video or video).


The clear sector accounted for a whopping 45%+- of the total peak white level attainable. This much from the clear sector really dilutes the primaries and raised the unit’s black level a significant amount.


The clear section was completely blocked by a high-temp coating that has proven over time to be completely stable and permanent. Also the gaps between the color-wheel's dichroic segments of glass have been permanently filled with a hi-temp black silicone. The DMD chamber has been blacked out along with a strip of the chassis along the light path.


The unit only had a partial halo mask installed from the factory that only covered 50% of the boarder (2 sides only) of the DMD active surface. A mask was added to the two remaining boarders for 100% perimeter coverage of the active area along with modifying the existing mask for much better performance. This results in a very faint light "halo" of a couple of inches around the image boarder, masked by most screen boarders. Note that this remaining halo is much lower in brightness than stock (down about 75% in brightness). This halo mod process make a "ship-in-the-bottle" look easy http://www.avsforum.com/ubb/biggrin.gif


As to the contrast ratio, I am having some difficulty measuring it as the black level has dropped below the useable resolution of my meter. Some gains in brightness due to realignment and fine tuning of the optical path (internal focusing, etc.) has given us a bit of the light back lost from the clear block and the green filter addition.


Overall, I find (and this is somewhat subjective, not withstanding AVIA/VE calibration) the "useable" brightness to be about the same as before, but with much, much better black level. I, like most, do not miss the extra brightness created by the clear section as it yielded whites that were greater than the sum of the primaries and it also whitewashed the colors.


As to gray scale reproduction, the scales clearly illustrated an over-boost from the clear sector above about 80% IRE. After blocking of the clear sector the scale retained points that are along the lines of the more familiar 2.2 curve at the top end. The bottom end illustrates that 0% IRE illumination is cut by more than half (again, can’t say exactly how much as it is below my meter’s minimum resolution). Between those two points the steps are almost identical to the stock unit.


There is still a slight green shift in the image, but it is just a fraction of what it was before. With a relatively minor color correction from a HTPC video card you should be in business.


In closing, it has been great working with Mike on this project. For me, it has yielded excellent data on DMD optical systems based on multiple optical lens and flat mirrors design vs. concave collection mirror systems as those used by Plus and NEC.


Thumper

 

[Robert Clark]

Thumper,


Sounds excellent. The "green shift" has, for me, been the one last thing keeping me from totally enjoying this otherwise fine projector, after the tearing problem was solved (of course this caused the green shift).

Do you have any idea if you will be able to mod other 1030's (mine, for example http://www.avsforum.com/ubb/smile.gif ) and how much will you charge?


Thanks...


Robert


------------------

Robert Clark

See our home theater (with very poor quality pics!)
http://albums.photopoint.com/j/Album...874&a=12744078

 

[mflaster]

There you go again, Thumper, mucking up my beautiful prose with those tedious facts... http://www.avsforum.com/ubb/smile.gif


Mike



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Join the NYC-area HT club! Send me e-mail!

 

[nigel_ht]

*sigh* I asked a question regarding gamme tables here:
http://www.avsforum.com/ubb/Forum10/HTML/007704.html

 

[jcebedo1]

wow. this thread is old. reminds me of what i did to my x1.