CurtPalme.com Home Theater Forum

**kal** · Posted: Mon Aug 15, 2016 1:23 am Post subject:

Thanks! It certainly has!

Kal

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

So, the things are not firm still, BUT:
I am thinking on a base price around 300USD for a set of mods.

It looks like this mod will be sold in conjunction with a specially modified VIM (since a few signals need to be extracted, and the video path jumped over).
Here there are several possibilities

-For fast turnaround I'd like the VIMs to be prepared and tested in advance. The customer should send in his/her VIM regardless, since I need a VIM source for the next mod.

-If the customer does want to keep his/her VIM then I think I'd have to charge some extra, since then I need to source the VIM myself.

-I'm not sure in this, but I have a few old Marquee 9000 VIMs as well, which are not regarded as high performers, but that does not matter here since the VIM in my mod is only used for sync processing and suplementary signal generation, and the Marquee 9000 VIM could just do that, if this indeed works, this could be the bargain option (no extra costs, no VIM needed to sent in, while my stock lasts...)

I won't take responsibilty to install my mod on MP modded boards (here mostly the VNB is the concern), since I have no knowledgde what was previously made to them.

In return I might offer my own mods on the VNB itself...

lydmann · Joined: 12 Aug 2006 Posts: 56 Location: Norway

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

jbltecnicspro · Joined: 23 Apr 2016 Posts: 512

So, not to be "that guy" in this thread but. Obviously, the problem with the future of CRT is that no one is making them any more. What would it take to actually get an operation going to start rebuilding tubes again? And / or manufacturing them? Surely the patents for these tubes will expire soon-ish? Unless that happens, I'm not sure there is a future for CRT. There's basically just the last of us who still have our projectors and that's it.

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

greg9518lc · Joined: 19 Apr 2016 Posts: 360

The reason CRT is so promising is there still development on perfecting
the perfect video chain. The other reason is that there is no other option
for picture quality. Sony 4k is just plain awful and JVC is a better option
but still no match for modded crt projectors. I sure I will get flamed for these
comments but I call it as I see it and sell these digital's for a living.

Screenshots can never do crt justice the camera is the weak link but is easy to
capture a digital projector because of the limitation of fixed pixel display technology.
Hence the words GOT PHOSPHOR "Hell Ya" GOT LAMP THRU A PIN HOLE "Hell No"

Now the best part is now it includes Barco guy's being able to receive let's say a clarity
mod that will take there projectors to another level.

So I am that guy that has faith in the future of crt. Doesn't hurt to have plenty of spare tubes and chasis to get me
thru the next 20 years.................

xmob135lc · Joined: 15 Sep 2012 Posts: 80

Someone , somewhere will make a single tube projector , have faith. Especially because we are not under the constraint of signals coming out of VGA connector without even line buffers anymore (luckily I might add) . Smile

**kal** · Posted: Sat Aug 20, 2016 4:06 pm Post subject:

xmob135lc · Joined: 15 Sep 2012 Posts: 80

Well, I wouldn't say it's because of fixed pixels, but because panel type projectors in use have whole frame time lit , basically still pictures and crt has great motion handling with its line by line update. There is no panel projector with a light engine suitable for per pixel dimming because of this reason. On the other hand not even crt-s truly have it because of overlap. It's even difficult with lasers & low drive voltages nevermind crt-s with hundreds and slow phosphor.

jbltecnicspro · Joined: 23 Apr 2016 Posts: 512

jbltecnicspro · Joined: 23 Apr 2016 Posts: 512

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

Screenshots can't do justice to the original image, not ever, as long as the screenshot ends up being displayed on your PC at a lower resolution and bit depth than the original image. Between being cropped, resized, and compressed at various stages, no screenshot you are likely to make or post or see is going to measure up to the original image.

xmob135lc · Joined: 15 Sep 2012 Posts: 80

greg9518lc · Joined: 19 Apr 2016 Posts: 360

greg9518lc · Joined: 19 Apr 2016 Posts: 360

Let the Beta testing begin looks like the boards have arrived are starting to be installed so we should
have some feedback soon. Look forward to some updates from Gjaky and his beta tester real soon.

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

I built a daughterboard again. And did some performance measurements.
On the first picture you can see the input "pulse", it equals one pixel at 1080P 72Hz. It does not look really square, but in fact my pulse generator has bandwidth well over 500Mhz, and my 275MHz oscilloscope is also much faster than any CRT amplifier can ever be.
The pulse fills 6 divisions vertically:

This is the output signal shape of the daughterboard, it fills 5.8 divisions vertically which equals to -0.3dB rolloff at 1080P 72Hz.

Of course in the end the whole signal chain have to be tuned together for the best bandwidth, these shots are for only demonstrating the raw power of this preamplifier.

mp20748 · Posted: Sun Sep 18, 2016 5:45 pm Post subject:

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

The output of the preamp is loaded with a simple 75Ohm SMD resistor (as normally it would connect to VNB's input)
On the bench I use an EMG 12563 pulse generator (It's Hungarian made instrument up to 300MHz, with <750ps rise time) or either a PC video card, the output is probed with a HP1120A 500MHz FET probe (with the appropriate divider used according it is a CRT out or preamp out stage).
With the projector it's motsly SMPTE resolution pattern and Ecrabb's multistep resolution pattern, and some standard materials like Baraka and Oblivion and so on.

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

Guys

Waveforms on test gear are not what matters. The image quality on the screen is what matters. Good luck in your endeavor.