OT: Dual CRT question.

MyST wrote on 1/10/2006, 7:16 PM
I'm looking at maybe buying a 19" Viewsonic CRT display to replace my 17" Viewsonic CRT as my main screen.
I'd like to keep the 17" and use it as a secondary display.
How close can you place CRTs without getting image distortion?
My 17" is around 6 years old, but the image quality is still good.
And before you mention LCDs, they are out of my price range.

Thanks for your help.



jrazz wrote on 1/10/2006, 7:19 PM
I had a 21" and a 17" and set them next to eachother w/o incident. Before you rule out the LCD, look on tigerdirect.com at the refurbs. The prices are very reasonable and shipping is a lot less than CRT's so they might be cheaper than you think.

j razz
GlennChan wrote on 1/10/2006, 8:23 PM
I need to keep a one inch gap between my CRTs, otherwise they interfere with each other's picture a little. The huge gap isn't too much of a problem for me though.
FuTz wrote on 1/10/2006, 10:35 PM
19" and 22" right beside each other and no problema...
Monitors without speakers (but usually speakers are shielded for that purpose, ain't it?)
John_Cline wrote on 1/11/2006, 5:58 AM
Generally speaking, you should not experience any interference between two monitors if; a) you are using a dual-head video card and not two, separate video cards and b) you are running the same screen resolution and refresh rates on both monitors.

MyST wrote on 1/11/2006, 7:05 AM
Iask because I have two MAG 17" XJ770 monitors here at work on a dual-head nVidia card.
I need to keep them at least 3" apart or the closest part of the screens starts turning different colours.
Mind you, I think they're pretty old. That's why I mentioned that my Viewsonic was about 6 years old.

Thanks for the input.

rmack350 wrote on 1/11/2006, 8:41 AM
It seems like it's a matter of how well shielded the monitors are. I have two 19" screens right next to each other. One exhibits a bit of flicker on the edge nearest the other.

Both are driven off the same card and running at the same settings but if you've ever fiddled with an XF86Config file in Linux you'll know that even a slight tweak will change your monitor frequency slightly. Similarly, opening up a control panel and adjusting the image position on a monitor works by changing timings. So having everything driven off the same card isn't a guarantee that the screens will be driven at the same exact speeds.

Newer monitors usually meet some pretty strict european EMI standards and I'm gonna make a guess that if the new one is well shielded it will neither affect not be affected by the older monitor.

Rob Mack
Coursedesign wrote on 1/11/2006, 9:01 AM
It's the electromagnetic deflection that interferes. This is a coil that moves the electron beam around the screen.

Even if the control signal frequency is totally identical and in phase, there will still be electromagnetic interference if they're too close.
rmack350 wrote on 1/11/2006, 9:25 AM
Would this be emenating from the back of the the CRT more than from the front?

Coursedesign wrote on 1/11/2006, 9:45 AM
The coil is around the neck of the CRT, so the field is indeed stronger in the back.

If only the field would stay there... :O)
jkrepner wrote on 1/11/2006, 12:13 PM
I had two identical 19" Viewsonic CRTs side-by-side and they hated each other. I now have two 21" Dell CRTs and they seem to show little to none of the flickering and color issues of the 19's. It could be that the coils (mentioned above) could be further apart, perhaps.

I think you need to just try it and see what happens. (Or get some lead plates)

Steve Mann wrote on 1/12/2006, 11:42 PM
Lead won't do anything about magnetic interference. Soft steel is best.

I have two Sony 19-inch monitors as close as possible to each other. Touching actually. Not a flicker from each other.

Also, two identical display cards will work as well as a dual-head card. You can use two different cards, but then you need to load two different drivers.

(You can put as many displays on your XP computer as you have PCI or AGP slots. I've seen gamers with six screens.)

Steve Mann
Jim H wrote on 1/14/2006, 9:57 AM
I just upgraded to two 19" Samsung Syncmaster 940B's for $300 each from NewEgg. I'd never go back to CRT. You spend 100% of your computer time staring at these things and my belief it's the best place to spend your money. Much less eye strain with these guys and I'm even able to increase from 1024x768 to 1280x1024 and still read text. The increase resolution also increases your workspace, not to mention the second monitor.
PumiceT wrote on 1/17/2006, 5:33 AM
I'd never go back to CRT.

How's your color and image accuracy on the LCDs? I've never seen an LCD that can show me what a CRT can show. Especially working with dark areas of images. Color has always been an issue, too. Have they somehow fixed this with newer LCDs?
Steve Mann wrote on 1/18/2006, 12:31 AM
I cannot imagine that you could use an LCD monitor to match color and levels like you can with a CRT. The LCD and CRT have different gamuts, so even properly calibrated the two would show non-primary colors differently. Further, how do you calibrate an LCD? You can’t. Each LCD pixel is either on or off, Speaking of off; you can’t get black from an LCD. When the pixel is “off”, it’s really mostly dark – not opaque. Turn off the room lights while displaying a black image and you’ll still see the backlight through the LCD. This means you’re your offset depends on the ambient light. Contrast on an LCD depends on the viewing angle, and the brightness is the intensity of the backlight. White is also not possible – you get whatever color the backlight is.

Sony sells an LCD field monitor for several thousand dollars, but I don’t know how they can get around the physical properties of LCD displays
GrenadaV wrote on 1/18/2006, 10:57 AM
I have to Sony G420 Trinitrons touching each other and no probs :)

(Would like one big 32" widescreen LCD though!)..:)
MyST wrote on 1/24/2006, 1:56 PM
I decided to go with another 17" Viewsonic. The Graphics series, G70fB.
$200 Canadian with a 3 year warrantee. Those are numbers I love!
I'm starting to get into graphic design more, and the CRTs are still highly recommended.
I won't lie though, if I had the funds, it would've been a couple of low refresh rate, high contrast ratio LCDs.
I should be getting it in the next few days.
Thanks for all the great input.

MyST wrote on 2/3/2006, 7:51 PM
I can breathe! I can breathe!!

Sooo much nicer!
I actually just tried having the second monitor as a preview window and... niiiice!
Acid, Corel Draw, etc, everything just gives you so much more breathing room with duals.
The proximity of one to the other isn't as big a problem as I'd feared, because I have a small surround speaker between both anyways. There's like 5" between each monitor.

Thanks again for all the input. Much appreciated as always!