CurtPalme.com Home Theater Forum

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

I suggest to you, GENTLY, that before you do any mods that affect any circuits that Mike has modded in your machine, that you consult with him about the mods first. Mike's mods tend to do more than just the single most obvious things, they're subtle and very, VERY well thought out, but also finely balanced. You would not want to start messing with his mods while doing your own, and end up with a poorly performing mess, would you?

COLLABORATE for best results.

mp20748 · Posted: Sat Mar 05, 2016 11:12 am Post subject:

redfox001 · Joined: 16 Mar 2009 Posts: 2257 Location: The Netherlands

Hmm running out of lies Very Happy

mp20748 · Posted: Sat Mar 05, 2016 11:23 am Post subject:

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Red, so I try to just make a reasonable suggestion and you decide to use it as an excuse to toss an insult my way...very interesting.

Some projects are never finished because I always believe that I can make more improvements. I'm not satisfied to hit the target, I'm barely satisfied to put every bullet in the bullseye. I want to put every bullet through the SAME HOLE in the dead center of the bullseye...at progressively greater distances with every shot.

Anyway, the HR tubes are an advantage that NOBODY else can touch. Sharper than LUGs if used correctly, combined with the best
magnetics and quiet, stable, high bandwidth magnetic control systems and video chains, it has the potential for a sharper picture than any other CRT projector ever made. With a little help and advice from others who've developed techniques for improvements that I fully intend to use, we'll get this done.

I do thank you for selling me the parts you were selling. I didn't even argue about the price, although I could have gotten the deflection and convergence yokes from Curt for a significantly lower price.

Maybe you'll note, I'm not generally argumentative, and in fact I try to get people to STOP arguing and show some respect for each other and the work they have done. But you seem to be resistant to taking that advice.

Oh well. I can't change you. I can only offer suggestions. If you are to change your argumentative ways and compulsion to try to claim that your methods and modifications are the best, in the absence of objective data that demonstrates it, then those changes will have to come from within YOU.

redfox001 · Joined: 16 Mar 2009 Posts: 2257 Location: The Netherlands

Removed

redfox001 · Joined: 16 Mar 2009 Posts: 2257 Location: The Netherlands

removed

mp20748 · Posted: Sat Mar 05, 2016 2:13 pm Post subject:

redfox001 · Joined: 16 Mar 2009 Posts: 2257 Location: The Netherlands

Removed

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Content removed because the problem has been addressed. Hopefully it won't happen again.

Spanky Ham · Joined: 22 Mar 2006 Posts: 5643 Location: Comedy Central

So, what is the difference in MTF at different contrast levels?

**kal** · Posted: Sat Mar 05, 2016 6:57 pm Post subject:

**Curt Palme** · Posted: Sat Mar 05, 2016 7:39 pm Post subject:

This is everyone's last warning. I am going through and deleting a few of the offensive posts here in a bit. Not only do some people insist on insulting others, dropping F bombs in the middle of technical information makes my forum look very unprofessional.

We've banned people here before, we can do it again. Of course that's not what we want to do, but I've had numerous discussions with various forum members how the forum(s) have become toxic, and frankly when I want to stop paying attention to my own forum due to insults, then obviously there's something wrong with some people's posts.

redfox001 · Joined: 16 Mar 2009 Posts: 2257 Location: The Netherlands

Ah ok I apologise for affending cmjohnson. I misread stuff sorry. You where probable realy helping I read it as sarcastical.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

It's OK, all is forgiven and all is well. I understand that language barriers could be at fault here.

In any event, just for future reference, I try to NOT use sarcasm on the internet simply because it's so hard to tell the difference between a sarcastic comment and one you mean.

So I don't do it. That makes it easier. Safer, too.

Yes, MTF values can and do change with contrast level changes, and anybody who ever ran the contrast level so high that he started to lose picture definition has seen it happen.

The reason for it happening at less-than-blooming levels is because the beam profile is not a square wave. It's normally a Gaussina profile, resembling the peak of a sine wave with a high aspect ratio. At higher contrast levels, the beam is functionally wider, as you can imagine slicing the top of a rounded cone (the gaussian shape in 3 dimensions) off at lower and lower levels.

If the beam profile was a perfect square wave, there would be no change in MTF with changes in picture level until you reached the point where there's spreading of the light emission within the phosphor itself.

Using Tse's method, you could take photos of your test patterns at various IRE and contrast levels and measure them for yourself, and you would see that there is in fact a change in MTF as picture level increases.

With visibly worn phosphor, you should see an improvement in MTF but at the expense of picture level.

redfox001 · Joined: 16 Mar 2009 Posts: 2257 Location: The Netherlands

Hi CMJohnson, I looked in my pictures and there is one picture showing the 1 on 1 off pixel pattern also outside the wear area. It also shows the contrast is at 70 and with a standard unmodified 9500 that means something. I measured the worn area to produce around 10 ftL with red and blue. So I guess the not worn area to be perhaps 11 ftL. So with full light the mtf still seems perfect. Really surprised me that is why I want to show it to the world Smile

Nash said he thinks the new marquees when adjusted well (pot) are a great machine. I still have to look into other potential problem areas but not time yet.

That it looks a bit unsharp in the edge is because me not focus corner yet nor optical neither electronical is not blooming Very Happy

But aaah I have to proof that. Later.

image by Radio Head, on Flickr

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

It does look good. Getting optimal sharpness in the corners is always a challenge. You've got to juggle the CPC rings, astig, focus, schemipflug, and mechanical focus to get it all right and after all that the lenses aren't perfect.

Since I run a 2:1 ratio screen, I don't worry about the extreme corners because they're off the screen. I do have to include them in some adjustments, of course, but if the corners of the 4:3 raster are acceptable, the corners of the 16:9 raster on my 2:1 screen tend to be very sharp.

I'm thinking about making a new screen, one that's a little bit taller. Not 4:3, but maybe 8:5 for a decent compromise.

Still, I would suggest that if you want to get the best out of your projector, whether it's just testing OR watching movies for enjoyment, that you make a proper screen. It doesn't have to cost much. Mine is just a sheet of masonite painted with ultra flat ultra white house paint. Cheap. Works well.

redfox001 · Joined: 16 Mar 2009 Posts: 2257 Location: The Netherlands

Yes you are right. In my real HT I have a bigger screen. I bought this screen from a paintersshop. It is thick linen portrait quality not expensive. I can get a bigger one on an alluminium frame but that is more expensive. I also have lug tubes in barco housings. If I can convince myself I will take thse to the marquee housing but first I want to be sure it worth all the trouble.

By the way I would love to see what thses HR tubes of you would do in this chasis! I figure that if they focus sharper and have 100% bandwidth it must be a picture noone has ever seen on crt. Perhaps some bertical scaling is needed to hide the scanlines but that seems very atainable. If you sell some tubes let me know!!!

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

That is my hope. To get the sharpest image ever seen on a 9" CRT projector. If there is a way to do it, to view UHD video on it, fully resolved as well.

I don't expect 4K. That would be incredible but I don't think it can be done at a refresh rate that is tolerable.

But I think that 3K is very possible.

Moome has announced that he is going to develop an HDMI 2.0 input card. Hopefully it will be available for Marquees and for other chassis, too.

If he designed it as a two board solution, with a separate, plug-in processor board and a projector interface board that is customized for each family of projectors, then that would be ideal.

I will be watching for another set of those tubes. I am sure that at least one more set exists, but it's in a working projector and I don't know where it is.

Spanky Ham · Joined: 22 Mar 2006 Posts: 5643 Location: Comedy Central