CurtPalme.com Home Theater Forum

[cmjohnson]

I doubt they're MCP types. Those are typically associated with tubes found in oscilloscopes which use electrostatic deflection.

The electron guns look pretty much like regular ones. Nothing dramatically different that I can see. Note the blue and white glass spacing units. The blue reportedly denotes a higher resolution type gun.

[redfox001]

Could be scatter-free phosphor. Normally there is gaussian blur comming from phosphor scattering. There are phosphors that blur much less.

[mp20748]

[barclay66]

[cmjohnson]

I've contacted Lexel and they're going to send me documentation on these tubes. I asked for the most complete information possible, including phosphor types, gun aperture specs, everything.

Hopefully I'll have that info in a few days.

[mp20748]

[cmjohnson]

So now that some mysteries of the LUG tubes have now finally been unravelled, do you think that there are any comparable improvements that might be made for LCP tubes as well? I find myself wondering if the default values of voltages and components connected to the tubes are the optimal values. You KNOW these projectors were designed from day 1 to be used in commercial, industrial, and military applications, not for movie watching, so I suppose it is possible that better image quality lurks behind a few changes nobody has yet thought to try.

"80 to 1 contrast ratio is enough" is the mindset of an engineer who never once thought about watching a movie on the unit or optimizing it for that application. Shortcomings are designed right into the circuits because of that.

[redfox001]

Have you figured out a way to get an analogue resolution beyond 1920x1080@72? Moome does not do it. Hdfury neither. Vga cards go till 2048x1536 but that is -3db. I am afraid you going to watch scanlines in far future lol

[cmjohnson]

Red, I would ask that you not make comments in my thread if they are not of a constructive, helpful, and technical nature.

I've already got something planned out. Fortunately I have a truly excellent engineer in my group of close friends, who can handle such relatively trivial jobs as getting RGBHV signals out of the HDMI data stream.

[cmjohnson]

I started reviewing Chris Stephens' marquee mod notes and making parts lists.

Wet tantalum capacitors can get very expensive.

The HVPS wet tant mod will cost about a thousand bucks in parts.

I'll buy them...but not all at once.

I figure that the baseline configuration for the projector that is intended to be 4K ready should start with the Stephens mod package,
combined with Mike Parker's latest best mods.

Add in a set of optimized Frankenyokes and the super res tubes, and by the time these things are done, by that time a way to pull the 4K RGBHV signal out of the HDMI data stream should have been developed.

The Moome Sony 1.4 card may be an answer. Not sure how high its resolution can run. But maybe a software upgrade to it will allow the highest resolutions.

SDI may be an option. But ultimately getting the RGBHV signals out of UHD will be the critical and final step.

[redfox001]

This was a geforce measured by Gjaky 2048x1536 this is reality man! Not quite 3840x2160. Perhaps someone can compensate these to do the max resolution. I would go for that.

image by Radio Head, on Flickr

https://www.curtpalme.com/forum_archived/viewtopic.php@t=35099.html

[cmjohnson]

The HTPC option is one I am considering. But I haven't even begun to look at the technical requirements and costs involved yet.

[redfox001]

Almost every vga card can do this they do not need to be super new. I think you can get a htpc second hand for little.

[cmjohnson]

Screw VGA. If it's not 4K capable it's not even worth considering. I won't spend money to build a PC that's yesterday's news.

The only reason I'd even consider an HTPC solution would be as a method of delivering content above 1080p resolution.

It'd give me a reason to buy some larger 4K monitors as well. Win-win.

[redfox001]

I mean if you buy a geforce card that I called a vga does not have to be the latest than it can do 2048x1536.

But in the Gjaky topic you see that intel GMA950 a very old card still does the same analogue resolution.

[redfox001]

Look here for 20 euro
http://www.ebay.nl/itm/ASUS-P5LD2-BVM-S-INTEL-945G-ICH7-AUS-MAXDATA-GMA-950-SATA-VGA-2-x-DDR2-RAM-TOP-/252068586658?hash=item3ab07564a2:g:4XgAAOSwcu5USM-F

[cmjohnson]

Thanks, but if I buy something for HTPC use it's going to be Nvidia based (I've had NO problems with nvidia, ever, and i'm loyal to them) and it's going to be (of course) 4K ready.

I could turn my workstation to the task. It's only a dual quad core Xeon machine with 24 GB of RAM and 5.1 TB of drive space.
Stick a suitable video card in it, load up FFDshow or whatever's the current hot software for HTPC, and go to town.

PROVIDED, of course, that the video card can deliver UHD over RGBHV. Or via HD component video, into a suitable transcoder.

[cmjohnson]

I just did some math, for fun.

Tse reported achieving a resolution of 2048x2048 (4:3 aspect ratio) with his test generator, which maxed out at that resolution, on the 8" version of these Lexel high resolution tubes for the 8500HR.

For reference, the resolution rating of an 8500 (any version) is 1600x1200.

2048/1600=1.28. So H resolution capacity increased by 1.28 times.
Vertically, it gets MORE interesting. 2048/1200=1.706666--- call it 1.7. So V resolution capacity increased by a whopping 1.7 times.

This IMPLIES that the HR tubes, even on an 8" machine, could go well beyond 2048 H resolution as that was the top resolution of Scott's generator.

But, let's be pessimistic and just use the lower value of 1.28 and assume that the HR version tubes are "only" good for a 1.28x resolution increase in both H and V.

A Marquee 9500LC is factory rated for a max resolution of 2500x2000.

Multiply those numbers by 1.28 and the new presumed resolution capacity of the 9" Lexel tubes is...
3200x2560.

What's the max rated resolution of the Barco Cine 9, the sharpest of them all?

3200x2560.

So, I seem to have scored a set of tubes that have the potential to match a Cine 9 and do it with the Marquee stock Thomson magnetics!

We KNOW that those focus yokes aren't as good as the ones Barco uses! Sharper IS possible doing nothing but retrofitting the proper focus yokes after they get slight modifications for compatibility.

Now let's consider the possiblity that the resolution gain noted in the vertical measurement IS possible in horizontal as well.

That'd be, being precise now, 1.7066667 times the original rated resolution.

Relative to a stock 9500LC's 2500x2000 resolution, that would be...

4266H by 3413V

YIKES.

Fully 4K-pable with the STOCK yokes.

Now for a brief venture into insanity:

About the time Scott was doing his own HR tube experiment, I was playing around with Frankenyokes for the first time,
and on my own test 8000 chassis and my own signal generator, that ALSO maxed out at 2048x2048, (Sencore CM2125),
I was able to get a visually fully resolved 1:1 test pattern at 2048x2048, ON THE TUBE FACE, with no capacity to measure the
MTF value but it was definitely pretty decent. This pattern could not be resolved on the screen as the HD-8B lenses just aren't
sharp enough, not even close. Tube under test was a green 180DMBHKA, the regular type for an 8000, I THINK. I did have
a P16DVB-something green tube that seemed to be sharper but I don't think that was the tube under test. I could be wrong but I don't think so.

So, with a better focus yoke on the STOCK tubes I was matching Scott's findings with the CUSTOM tubes?

Even to me that sounds like an outright fabrication.

Well, I may sometimes be wrong, but my personal sense of ethics forces me to never knowingly give false information.
I swear, I'm not lying, I'm just recalling what I actually did. Note that I do remember such trivialities as the model number
of the generator. If I could remember that, then I know I'm not making ANYTHING up.

So if I was able to push 1.7x the resolution out of stock tubes ONLY by using superior focus yokes, does it follow that using
equally superior focus yokes could AGAIN give the same amount of relative sharpness increase on another tube?

Let's play that game just for pure amusement.

I've got (theoretically) Cine 9 level resolution 3200x2560 at worst case and 4266 by 3413 at best case, with the stock yokes!



Based on previous math, we know that 2048/1200=1.706666 and 2048/1600=1.28

So the change-out to optimal focus yokes theoretically will boost resolution capacity by anything from 1.28 to 1.707 times.

This gives four limits for the outcome of this experiment assuming we just don't reach a hard beam diameter limit first.

Now remember, we have multiple scenarios to consider. Scott's findings indicated that the HR tubes had a resolution
increase of not less than 1.28 if you go with the H figure, and not less than 1.707 if you go with the V figure.


So we have to plan this out carefully:

Stock res (2500x2000) x 1.28 = A below. Presumed lower limit resolution of HR tube with stock magnetics. Call this "HR LOW".
Stock res (2500x2000) x 1.708 = B below. Presumed upper limit resolution of HR tube with stock magnetics. Call this "HR HIGH".

HR LOW is 3200x2560. Same as a Cine 9.
HR HIGH is 4265x3412. Already we're over 4K.

Now consider the possible effect of better focus magnetics.
This is based on my Frankenyoke experiments as described above. 2048x2048 well resolved on a tube intended for 1600x1200. Coincidentally, the ratio of improvement is the same as seen by Scott when using the HR tubes with stock magnetics.

So, HR LOW x 1.28 (low side improvement from better magnetics) = 4096x3277.
And HR LOW x 1.707 (high side improvement from better magnetics) = 5462x4370.

HR HIGH x 1.28 (low magnetics) = 5460x4367.
HR HIGH x 1.707 (high magnetics) = 7280x5824. (Well over 4K at 7680x4320.)



Let's face it, these are pie-in-the-sky figures. My odds of seeing the higher numbers no matter what I do are about the same
as seeing a real live unicorn winning the Triple Crown.

But it does give an idea of the potential sharpness of these tubes, if not the actual achievable resolution they could handle.

The highest resolution listing is firmly in 8K territory. (7680x4320) With room to spare.

In practice, the bandwidth required is IMPOSSIBLE in any practical terms, and the phosphor isn't going to be fine enough, either.

Cathode capacitance would probably kill any ability to resolve all that even if you did have the amplifiers and deflection
systems that were able to hit the required bandwidth and scan rates.

This is just a thought exercise for my own amusement. Thinking out loud and extrapolating future results from today's
known data.

The end result of all this is simply this: There is a very real possibility that I have the makings of a Cine 9 killer on my hands.

[tschaeikaei]

I didn't read the whole thread but since the wet tantalum caps appear again and again:
Where are you going to use them?
Redfox: what signal is this on that oscillogram? I can't remember seeing a signal like this on the scope before.
Looks a bit like h-sync but why are the HF blocks not equal in amplitude (voltage)?
Regards, Julian

[cmjohnson]

I wouldn't really expect anyone to read my previous wall of text. It's mostly there to remind ME of what may be possible with these tubes.

The usage of expensive wet tantalum capacitors will be limited to replacement or augmentation of electrolytic capacitors in critical circuit areas where they directly affect the slew rate of the related amplifiers and of the power supply. Basically, the electrolytics in the non-potted section of the HVPS and directly down the video amplifier chain. The two 100V electrolytics on a neck card would be replaced with wet tants, to give an important example.