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Screen gain for JVC D-ILA projector
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cynix



Joined: 12 Oct 2009
Posts: 38
Location: Scotland


PostLink    Posted: Wed Feb 20, 2019 11:02 pm    Post subject: Screen gain for JVC D-ILA projector Reply with quote


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Well I finally retired my XG135 and got a JVC X7900 but after watching my 1st movie on it tonight I have to say the "immersion" factor is just not there like with the XG at all.

Obviously the picture detail is a lot better, convergence is more or less perfect and the PJ itself is near silent, but the black level is poor and whites are quite overblown even with the iris closed down as far as possible in low lamp mode. I've played with gamma settings and improved it quite a bit but it's still not great, at best it's gone from poor to mediocre with settings adjustments.

I wonder if it's due to my 1.3 screen gain and would a 1.0 or even 0.9 gain bring the black level down to XG levels? I did read on here a few guys saying they thought the new JVC D-ILA models could equal a CRT on black level, so I wonder why mine is so poor in this respect.

I only have a 92" screen and the PJ is close to the minimum throw distance (can't be moved back) which doesn't help with the overblown brightness level, but at minimum iris and low lamp mode I was really expecting better. Could it just be I need a different screen?

I think a few of you guys have also gone for a JVC so would welcome any comments.

I'm almost tempted to try getting new tubes fitted to my XG after all, haha.

Thanks.
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kal
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Joined: 06 Mar 2006
Posts: 15749
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Thu Feb 21, 2019 1:51 pm    Post subject: Reply with quote

I'm surprised at this. The JVC DLA-X7900 is their mid-range offering (between the X5900 and below the high-end DLA-X9900), and a recently new model.

I have a mid-range JVC from back in late 2012 or so (the RS56) and yours should be better in all regards, and I have excellent results (and black levels) running mine on a ~1.1 gain screen. I don't think your 1.3 gain is what's causing you issues. You can read my initial thoughts here from a CRT owner after coming from a Zenith 1200 CRT (basically a rebranded Barco Cine 8 Onyx): http://www.curtpalme.com/forum/viewtopic.php?t=32973
I also owned a NEC XG-75 for a while.

There was really nothing I liked better with either the NEC or Barcos I've owned over the years.
Do you have a calibration report of any kind that shows how it's doing?

What do you mean by whites being overblown? Are you clipping/crushing whites?

Kal

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cynix



Joined: 12 Oct 2009
Posts: 38
Location: Scotland


PostLink    Posted: Thu Feb 21, 2019 3:32 pm    Post subject: Reply with quote

Thanks for the reply.

Is your RS56 the older type with 1300 lumens from the 230w lamp? Mine is 1900 lumens from the 265w lamp and that could be making the difference. I wonder if one of the old 1300 lumens lamps would work in the new models?

There's also the option of using an ND (neutral density) filter in front of the lens to lower the brightness, so I've ordered a cheap set to try and see how they look.

I've read that old thread right through about 3 times over the last year while contemplating retiring my XG135. Very Happy

I haven't calibrated the X7900 yet but I ordered a Spyder 5 to do it with. I don't think it'll make much difference as even just pausing a movie on a plain black screen you can see it looks grey and calibrating won't help that. Dark scenes just looked "washed out" with the high brightness and unrealistic.

The whites look too bright to the point of being distracting and again making the image look unrealistic. Maybe I'm just too used to my old XG135 which had nearly 8000 hours on the tubes. Smile

I turned down the "bright gamma" to -7 (it goes from -7 to +7, maybe your RS56 is the same) and the contrast to -5 and that helped a lot with the overblown whites, but with the iris already at -15 and low lamp mode enabled there's nothing else you can do for the black level. Like you said in that old thread, lowering the brightness setting doesn't actually lower the black level.

I read that the min to max throw distance makes a 30% difference in brightness (I'm almost at the minimum distance) + with my 1.3 gain screen and the 1900 lumen output compared to the 1300 lumens of the older models I think it could just be a combination of those things raising the black level, especially when I've been used to a CRT for nearly 20 years.
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cynix



Joined: 12 Oct 2009
Posts: 38
Location: Scotland


PostLink    Posted: Thu Feb 21, 2019 3:43 pm    Post subject: Reply with quote

Yeah, I looked up the RS56 specs... 230w lamp @ 1200 lumens, the X7900 is the 265w lamp @ 1900 lumens, that would make a big difference in black level alone.
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kal
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Joined: 06 Mar 2006
Posts: 15749
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Thu Feb 21, 2019 3:43 pm    Post subject: Reply with quote

Mine uses the JVC PK-L2312U lamp. It was the first gen with this new DC bulb that was supposed to be a lot more stable in terms of light output over time. Not sure what the wattage is or what lamps work with what models. I wouldn't attempt however to use any lamp that isn't the right one of the model you have.

cynix wrote:
I haven't calibrated the X7900 yet but I ordered a Spyder 5 to do it with. I don't think it'll make much difference as even just pausing a movie on a plain black screen you can see it looks grey and calibrating won't help that. Dark scenes just looked "washed out" with the high brightness and unrealistic.

Something sounds set up incorrectly in terms of brightness/contrast matching between your source and projector. Like for example, if you have one set to 16-235 and the other set to 0-255, it'll look the way you do. Flip it the other way and you'll get crushing/clipping. Calibrating will point this out to you as you'll see it. You don't need a meter for this however. Just put up a pattern near black and near white. Make sure your source and projector are set to both 0-255 or 16-235 (doesn't matter which). They just need to match.

Read this: http://www.curtpalme.com/forum/viewtopic.php?t=35322
Specifically the section "What is video levels calibration?" with the example pics.

Until you get it set up correctly don't try and fix problems with third party add-ons. You'll just make things worse. That includes messing around with settings like 'bright gamma'. In most cases your adjustments should be minor. (I know mine are - it was very close out of the box).

Good luck!

Kal

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kal
Forum Administrator


Joined: 06 Mar 2006
Posts: 15749
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Thu Feb 21, 2019 3:47 pm    Post subject: Reply with quote

cynix wrote:
Yeah, I looked up the RS56 specs... 230w lamp @ 1200 lumens, the X7900 is the 265w lamp @ 1900 lumens, that would make a big difference in black level alone.

Not necessarily. It depends on how the bulb is used/implemented.

Just like putting an engine in two different cars. How it results in terms of driving performance will depend on the rest of the vehicle.

Kal

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garyfritz



Joined: 08 Apr 2006
Posts: 10598
Location: Fort Collins, CO


PostLink    Posted: Thu Feb 21, 2019 4:16 pm    Post subject: Reply with quote

I wonder if I have a similar issue with my RS-45. I also have a 1.3 screen. I don't want to lower the overall level and crush the shadow detail, but black scenes are nowhere near black. Maybe it's time to pull out the calibration disks and figure out how to adjust the thing. Though I thought I ran basic calibration patterns through it when I got it, and the low-IRE calibration levels were basically invisible. Maybe my source (usually a cheap BD player) is not set right so it's boosting the low end?

This page says the Dark/Bright Level setting "allows easy gamma adjustment without complex gamma operation."
It looks like the [1-2-3] Custom Gamma setting lets you tweak the response curve directly. Maybe I need different presets for BD player, laptop, etc.

Sounds like I have a project...
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kal
Forum Administrator


Joined: 06 Mar 2006
Posts: 15749
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Thu Feb 21, 2019 4:29 pm    Post subject: Reply with quote

Throw up a calibration disc that has near black or near white patterns and check.

This one works well: http://www.curtpalme.com/ChromaPure_Calibration_Disc.shtm
See "STEP 2.2: Performing Video Levels Calibration" here: http://www.curtpalme.com/forum/viewtopic.php?t=35322

Patterns used:





Similar patterns are also available on the free AVS709 disc: https://www.avsforum.com/forum/139-display-calibration/948496-avs-hd-709-blu-ray-mp4-calibration.html

Kal

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garyfritz



Joined: 08 Apr 2006
Posts: 10598
Location: Fort Collins, CO


PostLink    Posted: Thu Feb 21, 2019 7:14 pm    Post subject: Reply with quote

Yeah I've got AVS709 and a couple of others. I just need to spend some time and do the checks. I'd like to at least get the levels set better so it's not so freaking bright when the screen goes (/is supposed to go) black. Hopefully I won't have to drag out the colorimeter too. I don't even remember how to run it any more...

I also need to check my devices and make sure they're all set for compatible levels, e.g. 0-255 vs 16-235 or whatever it is. Every devices seems to handle that differently so I'll have to find it. Looks like the JVC has different Input settings, and "Standard" is 16-235. I assume that's what I want from my BD player & PC.
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cynix



Joined: 12 Oct 2009
Posts: 38
Location: Scotland


PostLink    Posted: Thu Feb 21, 2019 8:40 pm    Post subject: Reply with quote

I'm sure it's not just a setup problem I'm seeing... all the hdmi stuff at both ends is on "auto" and if I switch the X7900 to the manual setting for "full range" the problem gets much worse and the black level is obviously terrible. The basic black level I'm disappointed with is nowhere near as bad as when you set the hdmi settings wrong.

It's just as if the iris could do with another 1 or 2 settings below -15 and since I also find the whites *way* brighter than those I was quite happy with on the XG135 I think lowering the overall brightness so that black is "blacker" and white is not so glaring would give a much better result. With the iris fully open this thing is ridiculous... unwatchable, headache inducing bright, and that's still in low lamp mode, haha.

They seem to aim for crazy high contrast ratios by pushing the white level higher and higher even if it means raising the black level slightly. On a 140" 1.0 gain screen it probably looks fine, on my 92" 1.3 gain, not so much. Also my room is completely blacked out even during the day, although the room itself isn't decorated to be dark... in a light room it probably would also look fine.

Will be interesting to try the ND filters to lower the overall brightness, hoping that will be a relatively easy answer.
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garyfritz



Joined: 08 Apr 2006
Posts: 10598
Location: Fort Collins, CO


PostLink    Posted: Thu Feb 21, 2019 9:33 pm    Post subject: Reply with quote

cynix wrote:
They seem to aim for crazy high contrast ratios by pushing the white level higher and higher even if it means raising the black level slightly.

It doesn't work like that. Contrast ratio is BrightLevel / DarkLevel. If they make everything brighter, the dark levels raise more (proportionally) and the CR goes DOWN. That's what kills your CR when you have ambient light in the theater.

Quote:
Will be interesting to try the ND filters to lower the overall brightness, hoping that will be a relatively easy answer.

That might help. It will lower the overall brightness AND raise the CR -- the opposite of what I described above. You could get a similar result with a lower-gain screen, possibly even gray.
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cynix



Joined: 12 Oct 2009
Posts: 38
Location: Scotland


PostLink    Posted: Thu Feb 21, 2019 10:46 pm    Post subject: Reply with quote

garyfritz wrote:
It doesn't work like that. Contrast ratio is BrightLevel / DarkLevel. If they make everything brighter, the dark levels raise more (proportionally) and the CR goes DOWN. That's what kills your CR when you have ambient light in the theater.


Interesting, thanks.

Quote:
That might help. It will lower the overall brightness AND raise the CR -- the opposite of what I described above. You could get a similar result with a lower-gain screen, possibly even gray.


I've ordered a cheap set of ND filters, with ND2, ND4, ND8 and ND16. If one of those basically does the trick then I'll order a much better quality one, apparently Hoya in Japan is one of the best makes and they have up to 82mm ND filters. There's a 112mm indent in front of the lens on the projector so I could get an aluminium ring machined to slot the ND filter in place permanently right in front of the lens.
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kal
Forum Administrator


Joined: 06 Mar 2006
Posts: 15749
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Thu Feb 21, 2019 11:42 pm    Post subject: Reply with quote

cynix wrote:
I'm sure it's not just a setup problem I'm seeing... all the hdmi stuff at both ends is on "auto"...

If things are on "auto" you don't know if it's 0-255 or 16-235. So how do you know it's not a setup problem?

You need to confirm what the device means when it's set to auto.

Quote:
and if I switch the X7900 to the manual setting for "full range" the problem gets much worse and the black level is obviously terrible.

But there's more than one way to have the two devices not match, and they produce different results (elevated blacks in one or crushed blacks in the other). Elevated blacks is much more noticeable because black becomes grey. Crushed means losing detail and is less noticeable.

Quote:
I think lowering the overall brightness so that black is "blacker" and white is not so glaring would give a much better result.

Except you can't do that with a digital. Other than putting a ND filter in front as you mentioned. Given this is a JVC, you shouldn't need to. I don't know any CRT owner who's moved to JVC DILA that finds this necessary, hence the reason I bet it's simply a setup issue.

Kal

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cynix



Joined: 12 Oct 2009
Posts: 38
Location: Scotland


PostLink    Posted: Fri Feb 22, 2019 12:23 am    Post subject: Reply with quote

kal wrote:
If things are on "auto" you don't know if it's 0-255 or 16-235. So how do you know it's not a setup problem?

You need to confirm what the device means when it's set to auto.


There's no manual option for selecting 0-255/16-235 on either of my source devices, but both are showing the same black level "problem". If either source device was set at the "wrong" black level then changing it manually on the JVC would improve the picture around black... in both cases it actually makes it *way* worse.

Even the black level when switching inputs with nothing on screen is the same grey as when pausing a movie on a black screen. I'm sure this is as black as the projector is capable of displaying on my screen.

Quote:
But there's more than one way to have the two devices not match, and they produce different results (elevated blacks in one or crushed blacks in the other). Elevated blacks is much more noticeable because black becomes grey. Crushed means losing detail and is less noticeable.


The black isn't crushed from either source device, the detail is there, the problem is that the absolute black level is too bright, not that the relative levels near black are wrong. Even if the black was crushed, correcting that wouldn't make the absolute black any darker which is what I want to achieve to be 100% happy with the picture. I'm sure a lot of people wouldn't even call it a problem... my brother is coming over tomorrow night to watch a movie and I'm 100% sure he won't even notice the "problem" black level when I point it out. Smile

Quote:
Except you can't do that with a digital. Other than putting a ND filter in front as you mentioned.


Yes, either that or going for the lower gain screen. But the ND filter is certainly a lot easier to try.

Quote:
Given this is a JVC, you shouldn't need to. I don't know any CRT owner who's moved to JVC DILA that finds this necessary, hence the reason I bet it's simply a setup issue.


But are they all using one of the newer 1900 lumens JVC's, with a small 1.3 gain screen at close to minimum throw distance? Just the screen size/gain and short throw distance will make the picture look about 100% brighter than on a medium sized 1.0 gain screen at max throw distance... on top of that the lamp is 50% brighter than the older models.

Thanks for all the comments, will update when I've tried the ND filters.

I also ordered a light meter, so hope to have some actual values for my "black" and "white" too.
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kal
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Joined: 06 Mar 2006
Posts: 15749
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Fri Feb 22, 2019 3:27 am    Post subject: Reply with quote

You raise a good point that I glossed over originally: Your small screen size and the short throw. Both mean more light output.

If the projector setup is all correct (sounds like you've done your homework) then the combination of those two certainly won't help. ND may be the way to go.

Kal

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garyfritz



Joined: 08 Apr 2006
Posts: 10598
Location: Fort Collins, CO


PostLink    Posted: Fri Feb 22, 2019 4:41 am    Post subject: Reply with quote

You should get yourself a copy of the AVS709 test disk Kal mentioned above. You'll be able to tell very clearly if you've got it set wrong.

And apparently I **DO**, or did. The first test pattern on that AVS709 disk displays flashing areas of 0-20 IRE, with interspersed steady areas of 16 IRE. 16 should be BLACK. You adjust things until the flashing in the 17 IRE range just disappears.

When I checked it this afternoon, my black level was so high I could nearly see the flashing with the lights on !! No wonder it looked too freakin' bright...

But I was *sure* I set it up properly when I got it. I went in later this evening to check again, and... it's exactly right. Almost can't see the flashing 17IRE. Somewhere during the digging around trying to remember how to set it, I must have fixed whatever was wrong...
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cynix



Joined: 12 Oct 2009
Posts: 38
Location: Scotland


PostLink    Posted: Fri Feb 22, 2019 1:43 pm    Post subject: Reply with quote

^^ Good to hear you've got things looking better. Smile

Not got my ND filters yet but I got the light meter today.

At centre of a pure white screen I have 17.8 foot lamberts, before it hits the 1.3 gain screen, so I guess that would make it 23.1 in reality, which I believe is indeed a bit too bright as it should be around 10-14 for a dark room? And that's in low lamp mode with iris closed down as much as possible. The black level was too low for the meter to measure.

And I think you guys are right about the max lumens of the lamp not necessarily being relevant, 'cause they can obviously set the low lamp mode to whatever they like, regardless of the max output of the lamp. So it's possible that the low lamp mode on the older 1200 lumens models is identical to the newer 1900 lumens models.
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garyfritz



Joined: 08 Apr 2006
Posts: 10598
Location: Fort Collins, CO


PostLink    Posted: Fri Feb 22, 2019 6:38 pm    Post subject: Reply with quote

10 is too dim. 14 is reasonable but more wouldn't hurt. You really ought to measure off the screen, so the screen's contribution is properly accounted for. That's crucial when measuring colors (e.g. grayscale) but it's useful for light levels too.

Your X7900 is rated 1900 lumens, presumably for max-bulb and max-iris. Not sure what it runs when stopped-down like you're running it, but I'll start with max. Your screen is 93" -- yes, that is a bit small for that bright a projector. I have a 1.3 98" screen that I ran with a dim Marquee 8500. It seems plenty bright with my 1300-lumen RS45 turned down low. 50% more lumens onto 11% less screen area would definitely give you more light than **I'd** need.

Your x7900 has a 16:9 panel, so assuming your 93" is measured across a 16:9 screen (== 81" x 45.5"), that's 25.6 sq ft. 1900 lumens spread over 25.6 sq ft should produce 1900 / 25.6 = ..... 74 ftL !??? Waaaiitt, that can't be right. My 98" screen is 85" x 48" = 28.5 sq ft, 1300 / 28.5 = 45.7 ftL at full brightness... and I know I have nowhere NEAR those levels. Kal, have I flushed all my memory of how to calculate light levels?? Where am I going wrong on these calculations?

And, oh snap, I forgot the gain. So yours is 74 * 1.3 = 96.2 ftL and mine is 45.7 * 1.3 = 59.4 ftL. I'm definitely doing something wrong.
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jbltecnicspro



Joined: 23 Apr 2016
Posts: 495



PostLink    Posted: Sat Feb 23, 2019 4:04 pm    Post subject: Reply with quote

I'm also going to throw in my vote for wrong setting. Your HDMI levels need to match each other. If you're sending in a 16-235 signal, and your projector is set for 0-255, then your black levels will be elevated and things really will look washed out.

The manual iris on the bright JVC projectors should still be able to close down enough to be too dim on your screen in low lamp mode, even if it's only "barely" too dim.
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cynix



Joined: 12 Oct 2009
Posts: 38
Location: Scotland


PostLink    Posted: Sat Feb 23, 2019 7:40 pm    Post subject: Reply with quote

It's definitely not the settings... probably like most here I've been calibrating brightness and contrast since the days of "A Video Standard" on laserdisc back in the 90's. Smile Having the HDMI settings wrong makes it *way* worse than what I'm not happy with here... I'm sure it's just a combination of the small, high gain screen and short throw distance being just a bit outside the spec's of what JVC had in mind. That and the fact I've been used to the low black and (relatively) low brightness levels of various NEC CRT projectors for the last 20 years.

If I can work out a way to lower my centre speaker a bit then I'll get a slightly bigger, maybe 12" wider, neutral gain screen and that will probably sort it out even without needing the ND filter. My centre speaker is currently on top of my (rarely used!) mid 90's 36" CRT TV which sits on the floor (really it's just a stand for my centre speaker)... so need to make some kind of cabinet to take the centre speaker with a shorter height flatscreen TV, a 32" or maybe a 40" with very small bezel might work and allow the centre speaker to sit about 6" lower.
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