The Three 1280x800 LED Clones - Page 4 - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #91 of 429 Old 08-06-2011, 12:25 AM - Thread Starter
AVS Special Member
 
MCaugusto's Avatar
 
Join Date: Aug 2001
Location: BOSTON --- MA ---
Posts: 1,250
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 46
Hmm, that's good to see already, a Canadian Optoma dealer advertising the ML-500 as available by the end of September for the expected msrp....Now, what's up with that contrast ratio figure of 2.000:1 versus the Acer K330 at 5.000:1 ? Hyperbole from Acer, since all three pjs look like clones ?
From reading many/many reviews of pjs it seems to me that when a manufacturer states such "huge" increase in native contrast ratio it is almost entirely due to a lower FULL-OFF black level instead of a higher FULL-ON white reading : a projector with a FULL-OFF black level of 0.02 ft-L and a FULL-ON white reading of 17 ft-L has half the native contrast ratio of another pj that has a FULL-OFF black level of 0.01 ft-L and the same FULL-ON white reading of 17 ft-L, even though both have the same amount of apparent onscreen brightness; The only reason one pj has twice the contrast ratio is entirely due to its lower black level and not because its onscreen brightness is twice as bright.
So, if that is the case here, which i strongly suspect, how did Acer manage to lower the native minimum black "floor" of the K330 to 2 1/2 times better than the Optoma ML-500, and yet both pjs look like they use the same internal components ? Hmm...
I guess to get to the bottom of this we'll have to wait until a reliable publication measures the Acer K330 native contrast ratio using an illuminance light meter.
MCaugusto is online now  
Sponsored Links
Advertisement
 
post #92 of 429 Old 08-07-2011, 11:49 PM
Advanced Member
 
DLPProjectorfan's Avatar
 
Join Date: May 2010
Posts: 792
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 34
MCaugusto ? we have seen the Viewsonic projector PLED-W500 LED on some of the review sites, but if you go to their website from Viewsonic, the picture they have for the PLED-W500 LED looks different than what we have seen.
DLPProjectorfan is offline  
post #93 of 429 Old 08-07-2011, 11:52 PM
Advanced Member
 
DLPProjectorfan's Avatar
 
Join Date: May 2010
Posts: 792
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 34
On Viewsonic's website, the case of it looks like what we have seen on the review sites and from Optoma and Acer, but there is a hump on the top where the lens is, and all the bottons are on the back top, not like the cheap look of one of those pictures we have seen it looking like a cheap Chinese knockoff.
DLPProjectorfan is offline  
post #94 of 429 Old 08-08-2011, 12:24 AM
AVS Special Member
 
eat meat's Avatar
 
Join Date: Nov 2010
Posts: 1,560
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
http://www.viewsonic.com/infocomm11/Page4.html
both are pics of the w200

__________________________________________
Are you classified as human? Negative, I am a meat Popsicle.

(fifth element)
__________________________________________
eat meat is offline  
post #95 of 429 Old 08-08-2011, 12:42 AM
Newbie
 
knyz's Avatar
 
Join Date: Jan 2010
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Don't compare the Lumen from LED TO LCD or Another.

The Lumen LED is 10x the LCD possibility, that mean a 300 Lumen LED look like a 3000 LCD, anyway the Lumen LED have better color, better contrast and better quality of picture, you don't see any box line problem on LED !

Now from what i saw... the QUMI have actually a better quality on the same size than any Plasma or LCD !

The Plasma have a bad brightness and the LCD/LED have a bad black... etc..

The QUMI have deep color, deep back and excellent bright, it's really pretty incredible from a small box like the QUMI .

Now the QUMI are not perfect with need more setting, etc.. but i guess vivitek can give a full support and maybe update firmware to fixe some problem.

And the life from LED Lumen is better than any another Lumen LCD etc...
knyz is offline  
post #96 of 429 Old 08-08-2011, 06:36 AM - Thread Starter
AVS Special Member
 
MCaugusto's Avatar
 
Join Date: Aug 2001
Location: BOSTON --- MA ---
Posts: 1,250
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 46
DLProjectorfan >>> Thanks for the info on the link to J&R store which is already taking pre-orders for the Optoma ML-500 for less than the msrp ! That's great news, they're finally arriving...Now, let's hope these pjs will deliver on all their technology promises of 500 LED lumens (hopefully just a little less after calibration), very sharp 1280x800 picture (apparently the Pico DMD chip from TI uses diamond-shaped pixels), acceptable contrast ratio, easy input compatibility, etc, and NO startup focus issues, green/pink image shading, chromatic aberration, blurry pixels, etc.
As soon as i get my hands on the owner's manuals for the Optoma ML-500 and the Acer K330 i'll be able to make a more informed decision and then proceed to Amazon, or J&R, or B&H, or any other online retailer with full returns/no restocking fees.
Perhaps from right here at AVS, hmm ?
MCaugusto is online now  
post #97 of 429 Old 08-08-2011, 07:58 AM
AVS Special Member
 
blee0120's Avatar
 
Join Date: Oct 2009
Location: Merillville, IN 46410
Posts: 3,730
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 118 Post(s)
Liked: 74
Quote:
Originally Posted by MCaugusto View Post

DLProjectorfan >>> Thanks for the info on the link to J&R store which is already taking pre-orders for the Optoma ML-500 for less than the msrp ! That's great news, they're finally arriving...Now, let's hope these pjs will deliver on all their technology promises of 500 LED lumens (hopefully just a little less after calibration), very sharp 1280x800 picture (apparently the Pico DMD chip from TI uses diamond-shaped pixels), acceptable contrast ratio, easy input compatibility, etc, and NO startup focus issues, green/pink image shading, chromatic aberration, blurry pixels, etc.
As soon as i get my hands on the owner's manuals for the Optoma ML-500 and the Acer K330 i'll be able to make a more informed decision and then proceed to Amazon, or J&R, or B&H, or any other online retailer with full returns/no restocking fees.
Perhaps from right here at AVS, hmm ?

I want to hit the pre order button, but I'm waiting to see what else the acer has to offer. Basically, what type of video files that it plays. The ML500 supports a lot that I use
blee0120 is offline  
post #98 of 429 Old 08-08-2011, 09:23 AM
AVS Special Member
 
zombie10k's Avatar
 
Join Date: Dec 2007
Posts: 7,715
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 349 Post(s)
Liked: 394
are any of the 3 going to Nvidia 3D vision certified like the Acer 5360?

it would be nice to just connect to the HTPC without any inf spoofing, etc.
zombie10k is online now  
post #99 of 429 Old 08-09-2011, 06:55 PM - Thread Starter
AVS Special Member
 
MCaugusto's Avatar
 
Join Date: Aug 2001
Location: BOSTON --- MA ---
Posts: 1,250
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 46
OK guys, thanks to dreambeam and Raine0 over at the Acer K330 thread who posted links to test reports on the Chinese website ZOL.com on The Viewsonic PLD-W500 and the Acer K330, i compiled this "test results comparison chart".

-------------------------------VIVITEK QUMI --- VIEWSONIC PLD-W500 --- ACER K330 ---- NEC L50W --------- OPTOMA ML500 ------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum Lumen Brightness : 181 --------------------- 421 ------------------ 417 --------------332 ---------------- 429 -------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
ANSI Optimized Brightness : 110 --------------------- 371 ------------------- 328 --------------312 ----------------- 330 ------
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
ANSI Contrast ::::::::::::::: :: 30:1 --------------------- 238:1 ---------------- 59:1 ------------218.1 ------------- 159:1 -------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
FULL-ON/FULL-OFF Contrast : 1.560:1 ---------------- 1.475:1 --------------- 3.186:1 ---------2.990:1 ---------- 1.538:1 -------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Color Saturation ::::::::::::::: 128.2% ------------------ 62% ----------------- 89.16% -----------105.0% ---------- 123.8% -------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Brightness Uniformity Center :: 1.39 -------------------- 1.18 -------------------- 1.10 --------------1.16 ------------ 1.18 --------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Brightness Uniformity Corner :: 2.19 ------------------ 1.74 -------------------- 1.39 --------------1.37 -------------- 1.61 -------
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Color Uniformity Center ::::::: 0.018 ------------------- 0.010 ------------------ 0.010 --------------0.010 ----------- 0.009 -------
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Color Uniformity Corner ::::::: 0.021 ------------------- 0.016 ------------------ 0.012 --------------0.014 ----------- 0.016 -------
-----------------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum Power Use ::::::::: 53 watts --------------- 88 watts --------------- 88 watts --------- 80watts --------- 84 watts ---------
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Economy Power Mode ::::::::: 17 watts --------------- 62 watts -------------- 52 watts ---------- 46watts --------- 59 watts ----
-----------------------------------------------------------------------------------------------------------------------------------------------------------------
Temperature Hottest Port - Celsius : 66 degrees ---- 62 degrees ------------- 59 degrees ------ 69 degrees ------ 66 degrees ----
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Temperature Average ::::::::::: 38 degrees ---------- 39 degrees ---------------- 31 degrees ----------- 44 degrees ------- 38 degrees
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Brightness Uniformity of less than 1.5 is acceptable and less than 1.2 is almost imperceptible.
Color Non-uniformity : the human eye can distinguish 0.003 deviation and acceptable values are between 0.001 to 0.010 range deviation.
Color saturation standard chosen for tests was NTSC RGB; According to ZOL.com and verified by online articles, the measurements for mainstream LCD and CRT monitors are on average about 70%~75% color range of NTSC RGB, for comparison.
Screen size used during testing was 3 meters or 100 inches diagonal.
No noise measurement given for any projector, unfortunately.
Hottest air exhaust port located on front of projector next to lens AND secondary port on left side of case, with the exception of the Qumi and NEC which displayed highest thermal exhaust temperature on port located on left side of case and away from lens, which is preferable.
Comments such as extremely detailed image, excellent shadow detail, good thermal design and rather low readings for hot air exhaust temperature, very good/clear text display. Viewsonic W500 displayed well-saturated colors with the exception of RED, which was lacking while Acer K330 displayed excellent RGB colors but RED was overemphasized and BLUE was very accurate.
Some of my comments would be : lumen brightness much less than spec'd, especially the Qumi at 181 lumens followed by the NEC L50W at 332 lumens, and that's not even calibrated.
It appears that the Acer K330 and NEC L50W have essentially double the FO/FO contrast ratio of the Viewsonic W500 and Optoma ML500, 3.000:1 versus 1.500:1; However, the Viewsonic has more lumen output than other pjs, particularly when measured by using ANSI test image, 371 lumens versus an average of 325 lumens for the other three pjs...
No description for any controls for CMS, grey-scale tracking, gamma, etc, so we'll have to wait for owner's manuals to be released.
LL
LL
LL
LL
LL
MCaugusto is online now  
post #100 of 429 Old 08-09-2011, 11:51 PM
Member
 
Mr.Fresnel's Avatar
 
Join Date: Feb 2011
Posts: 46
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thank you MCaugusto for doing the helpful side by side!

IT looks like these twins are not as identical as we thought (Assuming the chinese site did their homework correctly).

The Viewsonic W500 seems to be tuned to run brighter, hotter and consume more watts. While the Acer appears to be tuned for moderate accuracy.

Does this mean the Luminus LEDs are driven harder on the Viewsonic? Could the way they are tuned significantly affect each model's longevity?

Liking the Viewsonic's brightness so far, but I have to respect Acer for not going BALLs to the Wall with the new chipset. Usually slow and steady wins the race.

... And all that jazz.

Mr.Fresnel is offline  
post #101 of 429 Old 08-10-2011, 01:17 AM
AVS Special Member
 
eat meat's Avatar
 
Join Date: Nov 2010
Posts: 1,560
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Its the way they are set up most likely the color contrast and brightness(even wattage) tell the tale.

__________________________________________
Are you classified as human? Negative, I am a meat Popsicle.

(fifth element)
__________________________________________
eat meat is offline  
post #102 of 429 Old 08-10-2011, 03:24 AM - Thread Starter
AVS Special Member
 
MCaugusto's Avatar
 
Join Date: Aug 2001
Location: BOSTON --- MA ---
Posts: 1,250
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 46
i was re-reading these test results and was struck by the very low 30:1 ANSI contrast ratio of the Vivitek Qumi and yet it turned out an acceptable FO/FO contrast ratio of 1.560:1, go figure.
Considering that both the Acer K330 and the Viewsonic W500 draw only 90 watts at maximum power usage, about the same amount of power used by the current generation of LED presentation pjs that employ the PT-54 LED chipset from Luminus Devices, i am now wondering if these brand new pjs are indeed using the PT-54 chip, contrary to my previous assumption; According to TI the new 1280x800 "Pico" DMD chip has much improved brightness as well as lower power consumption then previous generation of DMD chips, so perhaps that would account for the fact that both pjs use only 90 watts of power and yet both include a LED lightsource capable of producing up to 421 lumens measured brightness ?
However, considering all that, why did the Vivitek Qumi measured only 181 lumens at maximum power use ? That doesn't make sense.
Aesthetically speaking, after seeing these new pics i think the "high gloss black case + silver accent lens" Acer K330 looks much/much nicer than the mostly "plasticky white w/too few silver highlights" Viewsonic W500, but of course such are minor, irrelevant considerations on the subject matter...
MCaugusto is online now  
post #103 of 429 Old 08-11-2011, 12:35 AM
AVS Special Member
 
Raul GS's Avatar
 
Join Date: Feb 2003
Posts: 2,194
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 24
Quote:
Originally Posted by MCaugusto View Post
i was re-reading these test results and was struck by the very low 30:1 ANSI contrast ratio of the Vivitek Qumi and yet it turned out an acceptable FO/FO contrast ratio of 1.560:1, go figure.
One has little to do with the other. CRT FPs have very poor ANSI contrast, especially compared to DLP FPs, but the top CRT units have far better On/Off CRs than any digital FP...yes far better than the top of the line JVCs and 3 chip DLPs.

Ignorance more frequently begets confidence, than it does knowledge. Charles Darwin
Raul GS is offline  
post #104 of 429 Old 08-11-2011, 01:43 AM
Member
 
dreambeam's Avatar
 
Join Date: Mar 2010
Posts: 29
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thanks MCaugusto for matching the tech data of Qumi and new 500lumens leds.

There is another side by side review of ACER K330 and Viewsonic PLED W-500 here
dreambeam is offline  
post #105 of 429 Old 08-11-2011, 03:37 AM
AVS Special Member
 
eat meat's Avatar
 
Join Date: Nov 2010
Posts: 1,560
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
From the test image comparison, two products in the projection effect on the PPT document almost the same. The projection of the text and tables, it may be higher because of the quality of the lens, the Acer K330 sharper text, is also relatively more clear in the presentation, will have better business results.
does any one really think there is different led, dmd chip or lens on the 2 pjs?

__________________________________________
Are you classified as human? Negative, I am a meat Popsicle.

(fifth element)
__________________________________________
eat meat is offline  
post #106 of 429 Old 08-11-2011, 09:40 AM
Member
 
anomaly123's Avatar
 
Join Date: Aug 2011
Posts: 64
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Take it for what its worth, here are the reasons why there are discrepancies

Quote:
Originally Posted by MCaugusto View Post

i was re-reading these test results and was struck by the very low 30:1 ANSI contrast ratio of the Vivitek Qumi and yet it turned out an acceptable FO/FO contrast ratio of 1.560:1, go figure.

When a DLP system is displaying pure black, the light is sent to a "light dump" inside the optics so it does not reach the screen. When it is displaying something white, the light is sent towards the screen. When there are issues with the optics system design, there will either be light leakage onto the screen when its suppose to be all black, or there will be light leakage when the screen is white. In this case, Full on full off is as expected, in the thousands, so it looks like full black is ok, and the light leakage is masked when the screen is full white, so its not picked up by the measuring equipment.

The ANSI pattern is a checkerboard with half the area white and half the area black, and it can reveal deficiencies in the optics. The ANSI contrast drops under 50:1 and this suggests there is light leakage of the whites and this in turn affects the blacks when shown simultaneously. This "issue" is very likely optics related and very fundamental.

Quote:
Originally Posted by MCaugusto View Post

Considering that both the Acer K330 and the Viewsonic W500 draw only 90 watts at maximum power usage, about the same amount of power used by the current generation of LED presentation pjs that employ the PT-54 LED chipset from Luminus Devices, i am now wondering if these brand new pjs are indeed using the PT-54 chip, contrary to my previous assumption;

These 2 projectors are indeed using the Luminus PT-54 Chipsets and also the same 0.45" DMD panels, and they both are indeed the one and the same optics. The Luminus PT-120 is usually water cooled and the optical etendue of the LED emitter is too large for a tiny 0.45" panel to catch. Using a PT-120 on a 0.45" panel would be a total waste.

Quote:
Originally Posted by MCaugusto View Post

According to TI the new 1280x800 "Pico" DMD chip has much improved brightness as well as lower power consumption then previous generation of DMD chips, so perhaps that would account for the fact that both pjs use only 90 watts of power and yet both include a LED lightsource capable of producing up to 421 lumens measured brightness ?

The brightness difference comes from the mixing of a white field in addition to the red/green/blue fields. If you look at the color saturation spec, Qumi shows 128%, Acer shows about 100%, Viewsonic shows about 60%. RGB LEDs usually form a 120%~130% NTSC gamut due to the green at 520nm wavelength. What white mixing does is turn on R/G/B at the same time when the panel is showing a white field. The drawback is one trades color gamut area with brightness because the RGB primaries on the CIE1931 chart shift towards the center.

It is likely the Qumi is not doing white mixing, the Acer is doing slight white mixing, and the Viewsonic is doing heavy white mixing. This is a pure electronics tuning issue and depends on the target specs of the projector.

Quote:
Originally Posted by MCaugusto View Post

However, considering all that, why did the Vivitek Qumi measured only 181 lumens at maximum power use ? That doesn't make sense.
...

Qumi uses the smaller PT39 chipset, doesn't run a white field like its bigger brothers, and uses different optics that potentially has issues. The test results for ANSI lumens of 110 and contrast of 30:1 says it all.
anomaly123 is offline  
post #107 of 429 Old 08-11-2011, 11:15 AM
AVS Special Member
 
zombie10k's Avatar
 
Join Date: Dec 2007
Posts: 7,715
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 349 Post(s)
Liked: 394
@ anomaly123 - thanks for posting, sounds like you know your projectors.

according to the chinese review posted, it sounds like the Acer will be more HT oriented than the viewsonic.
zombie10k is online now  
post #108 of 429 Old 08-11-2011, 11:21 AM
Senior Member
 
Raine0's Avatar
 
Join Date: Mar 2008
Posts: 284
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Now roll on Optoma, so we all can be a bit more decisive.

But seeing as the 'marketing' contrast value of the Optoma is still at 2000:1. It seems, dare I say, that the Acer might pip the field for HT use.
Raine0 is offline  
post #109 of 429 Old 08-11-2011, 12:04 PM
AVS Special Member
 
eat meat's Avatar
 
Join Date: Nov 2010
Posts: 1,560
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Raine0 View Post

Now roll on Optoma, so we all can be a bit more decisive.

But seeing as the 'marketing' contrast value of the Optoma is still at 2000:1. It seems, dare I say, that the Acer might pip the field for HT use.

depends really, most want a less saturated color gamut for ht.

__________________________________________
Are you classified as human? Negative, I am a meat Popsicle.

(fifth element)
__________________________________________
eat meat is offline  
post #110 of 429 Old 08-11-2011, 01:23 PM
Senior Member
 
Brian M's Avatar
 
Join Date: Feb 2006
Location: Tennessee
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Few quick questions on these.
1.would 3d look descent on these?
2.what would the maxiumum size projection be before loss in quality?
3.what gain screen would be reccomended to get best picture results?
Brian M is offline  
post #111 of 429 Old 08-11-2011, 01:48 PM
Senior Member
 
Raine0's Avatar
 
Join Date: Mar 2008
Posts: 284
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Tbh Brian I don't think anybody here can give u solid answers on those questions. Unless u happen to know that Chinese guy who reviewed the Acer and Viewsonic models.
Raine0 is offline  
post #112 of 429 Old 08-12-2011, 01:10 AM
Member
 
anomaly123's Avatar
 
Join Date: Aug 2011
Posts: 64
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by anomaly123 View Post


The brightness difference comes from the mixing of a white field in addition to the red/green/blue fields. If you look at the color saturation spec, Qumi shows 128%, Acer shows about 100%, Viewsonic shows about 60%. RGB LEDs usually form a 120%~130% NTSC gamut due to the green at 520nm wavelength. What white mixing does is turn on R/G/B at the same time when the panel is showing a white field

whoops, I screwed up folks. I busted out the oscilloscope and measured the LED pulsing sequence of a Qumi I have here.

Qumi does in fact mix additional colors in certain modes to get extra brightness (notably bright mode)

Qumi's field sequence is Cyan -> Blue -> Red -> Yellow -> Green. The field rate is 1200Hz when the input is 60Hz from a computer.

When the Qumi is not mixing colors (ie. when the color is actually closer to 6500K), the field sequence is Red -> Green -> Blue, and the field rate is 720Hz when the input is 60Hz from a computer.

These projectors are doing some clever electronic manipulation of the lights to get the brightness. But in my opinion, the optical system has to be up to standard to get the most from the electonics. Qumi is a tad disappointing from what I've seen here.
anomaly123 is offline  
post #113 of 429 Old 08-12-2011, 03:18 AM - Thread Starter
AVS Special Member
 
MCaugusto's Avatar
 
Join Date: Aug 2001
Location: BOSTON --- MA ---
Posts: 1,250
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 46
anomaly123 >>> So, apparently you have access to some testing equipment (luminance meter ? colorimeter?) and a Qumi pj and that's how you were able to ascertain that the Qumi uses the PT-39 LED chipset, not the PT-54 ? Did you open the case, and that's how you were able to confirm it ? Not that i doubt you, it's just that i have never seen that mentioned by anyone before, especially considering that the PT-39 was used on the first generation of portable LED pjs such as my two year-old LG HS-201; However your observation makes sense after i noticed the maximum lumen output of 181 lumens for the Qumi, which is about the same as for the HS-201...
I am now assuming that these new 500 lumen pjs are still using the PT-54 chipset based on their power usage of less than 90 watts, but it's still an assumption until i hear otherwise from any of the companies involved or someone that can confirm it with absolute certainty.
Considering how many users on the Qumi thread are reporting major focus issues at start-up and noticing that the air outake vent is located right next to the lens i am wondering if that could be the cause of the problem, and i am now concerned after seeing that all three 500 lumen pjs also have air outake vents placed in the same location.
I remember reading a review of a top-notch $10,000 Marantz pj some years ago in which the reviewer described the exact same problem and he was sure it was all related to the location of the outake vent right next to that top-of-the-line piece of optical lens !
MCaugusto is online now  
post #114 of 429 Old 08-12-2011, 07:19 AM
Member
 
anomaly123's Avatar
 
Join Date: Aug 2011
Posts: 64
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by MCaugusto View Post

anomaly123 >>> So, apparently you have access to some testing equipment (luminance meter ? colorimeter?) and a Qumi pj and that's how you were able to ascertain that the Qumi uses the PT-39 LED chipset, not the PT-54 ? Did you open the case, and that's how you were able to confirm it ? Not that i doubt you, it's just that i have never seen that mentioned by anyone before, especially considering that the PT-39 was used on the first generation of portable LED pjs such as my two year-old LG HS-201;

My company is involved in the projector industry and my engineers teardown projectors of interest on a regular basis. The Qumi report landed on my desk yesterday, but unfortunately I cannot share said report since it is strictly internal. We put the Qumi through its paces by doing a full barrage of optical, mechanical and electrical measurements with proper lab grade test equipment with a proper test environment. From the LED die measurments, we determined the LEDs match the PT-39. We were hoping to get the newer SBT-39 LEDs, but it seems like they are not being used for the Qumi


Quote:
Originally Posted by MCaugusto View Post

I am now assuming that these new 500 lumen pjs are still using the PT-54 chipset based on their power usage of less than 90 watts, but it's still an assumption until i hear otherwise from any of the companies involved or someone that can confirm it with absolute certainty.

We don't have one of the 500 lumen models in our labs for teardown yet, but this will change fairly soon. I am 99% sure that the 500 lumen models use the PT-54 based on their power consumption and the real world tested lumens by various early sources. If we were to engage in a projector design for a 0.45" DMD, the PT-54 would be the absolute upper limit in terms of LED size that we'd use as a starting point, a larger LED and giving the sucker more power will not gain any more brightness out of the lens


Quote:
Originally Posted by MCaugusto View Post

Considering how many users on the Qumi thread are reporting major focus issues at start-up and noticing that the air outake vent is located right next to the lens i am wondering if that could be the cause of the problem, and i am now concerned after seeing that all three 500 lumen pjs also have air outake vents placed in the same location.

While I cannot comment on specifics, the Qumi does not have a "balanced" optics system design. The quality of the projection lens is good, but I would consider the light source part of the optics system to be mediocre. From an optical design standpoint, LED projectors are different beasts compared to UHP lamp projectors and many of the design techniques used in UHP lamp projectors simply cannot be applied to LED light sources because LEDs are somewhat unforgiving due to not being very bright in the first place and any drop in light output efficiency is very obvious on screen.
anomaly123 is offline  
post #115 of 429 Old 08-12-2011, 08:52 AM
Senior Member
 
Bsims2719's Avatar
 
Join Date: Apr 2004
Posts: 461
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Liked: 11
Quote:
Originally Posted by anomaly123 View Post

whoops, I screwed up folks. I busted out the oscilloscope and measured the LED pulsing sequence of a Qumi I have here.

Qumi does in fact mix additional colors in certain modes to get extra brightness (notably bright mode)

Qumi's field sequence is Cyan -> Blue -> Red -> Yellow -> Green. The field rate is 1200Hz when the input is 60Hz from a computer.

When the Qumi is not mixing colors (ie. when the color is actually closer to 6500K), the field sequence is Red -> Green -> Blue, and the field rate is 720Hz when the input is 60Hz from a computer.

These projectors are doing some clever electronic manipulation of the lights to get the brightness. But in my opinion, the optical system has to be up to standard to get the most from the electonics. Qumi is a tad disappointing from what I've seen here.

What is field rate? Is that the same as refresh?
Bsims2719 is offline  
post #116 of 429 Old 08-12-2011, 09:47 AM
Member
 
anomaly123's Avatar
 
Join Date: Aug 2011
Posts: 64
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Bsims2719 View Post

What is field rate? Is that the same as refresh?

The field rate is the frequency in which the display system updates its color fields. In a monochrome time sequential display (ie. DLP, HTPS, or LCOS), the simplest way to get a full color picture would be to show the observer a rapidly pulsing red -> green -> blue picture. Our brains will integrate this stimulus into a seemingly full color picture. If one were to show 1 red, 1 green and 1 blue field per full color frame and lets say the frame rate is 60Hz, you would end up with a 180Hz field rate (3 x 60).

When the Qumi is operating without color overlapping, the field sequence is red -> green -> blue, and for each full color frame, the RGB sequence is repeated 4 times. ie RGBRGBRGBRGB. This gets us 12 x 60 = 720Hz field rate.

When the Qumi is operating with color overlapping, the color field sequence is Cyan -> Blue -> Red -> Yellow -> Green. This is also repeated 4 times per full color frame, so you have CBRYGCBRYGCBRYGCBRYG running for each full color frame. When the input frame rate is 60Hz, you get 20 x 60 = 1200Hz

To get Cyan and Yellow from only 3 LEDs, which are red, green and blue respectively.

Cyan - Blue and Green turn on at the same time
Blue - Blue stays on, Green shuts off
Red - Red turns on, Blue shuts off
Yellow - Red stays on, Green turns on
Green - Green stays on, Red shuts off

Rinse and repeat
anomaly123 is offline  
post #117 of 429 Old 08-12-2011, 10:11 AM
Senior Member
 
PoisonWolf's Avatar
 
Join Date: Feb 2010
Posts: 280
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Anomaly, please stick around for a long long time. Your posts are extremely informative and helpful!

Having said that, why on earth did Vivitek market this thing as 300 lumens? Also, if they are using the PT-54 chipset on the newer "500 lumens" pjs coming out, this explains the increased noise db, as they need more cooling since these things are being pushed to their limits.

I wonder how this will affect the reliability of the product in the long run....

Quote:
Originally Posted by anomaly123 View Post

The field rate is the frequency in which the display system updates its color fields. In a monochrome time sequential display (ie. DLP, HTPS, or LCOS), the simplest way to get a full color picture would be to show the observer a rapidly pulsing red -> green -> blue picture. Our brains will integrate this stimulus into a seemingly full color picture. If one were to show 1 red, 1 green and 1 blue field per full color frame and lets say the frame rate is 60Hz, you would end up with a 180Hz field rate (3 x 60).

When the Qumi is operating without color overlapping, the field sequence is red -> green -> blue, and for each full color frame, the RGB sequence is repeated 4 times. ie RGBRGBRGBRGB. This gets us 12 x 60 = 720Hz field rate.

When the Qumi is operating with color overlapping, the color field sequence is Cyan -> Blue -> Red -> Yellow -> Green. This is also repeated 4 times per full color frame, so you have CBRYGCBRYGCBRYGCBRYG running for each full color frame. When the input frame rate is 60Hz, you get 20 x 60 = 1200Hz

To get Cyan and Yellow from only 3 LEDs, which are red, green and blue respectively.

Cyan - Blue and Green turn on at the same time
Blue - Blue stays on, Green shuts off
Red - Red turns on, Blue shuts off
Yellow - Red stays on, Green turns on
Green - Green stays on, Red shuts off

Rinse and repeat

PoisonWolf is offline  
post #118 of 429 Old 08-12-2011, 10:56 AM
Member
 
Mr.Fresnel's Avatar
 
Join Date: Feb 2011
Posts: 46
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by PoisonWolf View Post

Anomaly, please stick around for a long long time. Your posts are extremely informative and helpful!


Hear, hear!!!
Mr.Fresnel is offline  
post #119 of 429 Old 08-12-2011, 02:00 PM
AVS Special Member
 
donaldk's Avatar
 
Join Date: Aug 2006
Posts: 2,403
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 35 Post(s)
Liked: 16
Quote:
Originally Posted by MCaugusto View Post

i was re-reading these test results and was struck by the very low 30:1 ANSI contrast ratio of the Vivitek Qumi and yet it turned out an acceptable FO/FO contrast ratio of 1.560:1, go figure.
Considering that both the Acer K330 and the Viewsonic W500 draw only 90 watts at maximum power usage, about the same amount of power used by the current generation of LED presentation pjs that employ the PT-54 LED chipset from Luminus Devices, i am now wondering if these brand new pjs are indeed using the PT-54 chip, contrary to my previous assumption; According to TI the new 1280x800 "Pico" DMD chip has much improved brightness as well as lower power consumption then previous generation of DMD chips, so perhaps that would account for the fact that both pjs use only 90 watts of power and yet both include a LED lightsource capable of producing up to 421 lumens measured brightness ?
However, considering all that, why did the Vivitek Qumi measured only 181 lumens at maximum power use ? That doesn't make sense.
Aesthetically speaking, after seeing these new pics i think the "high gloss black case + silver accent lens" Acer K330 looks much/much nicer than the mostly "plasticky white w/too few silver highlights" Viewsonic W500, but of course such are minor, irrelevant considerations on the subject matter...

Well as mentioned in the Italian Qumi review video it uses the SBT-39 LEDs, not the PT-54, I believe Anomaly points this out as well. Ah well re-read, PT-39.

But it can't be just the electronics, as there's a considerable difference in brightness drop-off, as well.
donaldk is offline  
post #120 of 429 Old 08-12-2011, 02:05 PM
AVS Special Member
 
eat meat's Avatar
 
Join Date: Nov 2010
Posts: 1,560
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by PoisonWolf View Post

if they are using the PT-54 chipset on the newer "500 lumens" pjs coming out, this explains the increased noise db, as they need more cooling since these things are being pushed to their limits.

I wonder how this will affect the reliability of the product in the long run....



pushed to there limits?
pt-54
Red: 600-1,050 lumens
Green: 1,275-2,150 lumens
Blue: 275-480 lumens

__________________________________________
Are you classified as human? Negative, I am a meat Popsicle.

(fifth element)
__________________________________________
eat meat is offline  
Reply Digital Projectors - Under $3,000 USD MSRP

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off