15 Khz CRT vs 31 Khz CRT Arcade Monitor

[mamenewb100]

When I originally bought a Makvision 2929D monitor, I thought I'd made a great choice. Then later I learned it was a 31 Khz monitor that apparently doesn't look near as good as a standard 15 Khz monitor. Worse yet I couldn't exchange for another monitor because it would cost me over a hundred in shipping to send it back AND pay for the new ones return. So I was upset for awhile until I saw an old TMNT arcade cabinet at my local movie theater.

The monitor appeared to be a 15 Khz because it had the thick scanlines associated with it. However I thought the picture on my arcade monitor looked sharper. I understand that it's not Authentic for games designed for 240P displays to be displayed on 480P and it's twice the scanlines the older games were designed for. But  one argument I hear all the time is if you buy a 31 Khz CRT arcade monitor you wasted your money and might as well have got a regular LCD for much cheaper.

I think that's absurd because I have compared my LCD monitor to the CRT and it's not even close. The colors are better and more accurate on the CRT unless you get an expensive arcade LCD with low resolution. On a typical LCD you have to scale 240P to 720P or 1080P depending on the resolution of the LCD. Which makes an awful blurry pixelated picture. Obviously no scanlines either.

I agree if your looking for authenticity and nostalgia from looking just like it did in the past, then 15 Khz wins hands down. But I think a 31 Khz CRT display is kind of like adding antialising to the original game making it look better at the cost of authenticity.

This is of course just my opinion and it's subjective depending on how one looks at it. I understand this is kind of a moot point since CRTs are not sold new anymore. Just curious what others think. I attached some photos to critique. Unfortunately good pictures are difficult to get on a CRT.

[Jack Burton]

Many other things considered, it's possible that the monitor you saw at the movie theatre could have been out of focus, or just malfunctioning in other ways.

But yes, a 31khz CRT has many things going for it a LCD does not.  There's more to a good arcade image than resolution.   

[Minwah]

Best to worse:

15khz CRT
31khz CRT
LCD

I think 31khz CRT's can look pretty good with a fake scanline effect, otherwise the pixels look too square.

[mamenewb100]

Best to worse:

15khz CRT
31khz CRT
LCD

I think 31khz CRT's can look pretty good with a fake scanline effect, otherwise the pixels look too square.

I see what you are saying. It is blocky around the edges since it needs to draw two lines. At the same time the picture is brighter without the thicker scan lines. It's a compromise between the softer darker look of 15K and the brighter jaggy look of 32K. I would prefer 15 for really old classics like Donkey Kong.

[rCadeGaming]

A good 15kHz CRT doesn't have to be darker or excessively soft.  The TMNT cab just happened to have some problems.

[mamenewb100]

I just realized recently that MAME had an option to add artificial scanlines. It looks suprisingly realistic and is makes games like Mario Bros. look really nice. And yes I think the particular TMNT cab I looked at was not setup right and looked kind of off.

[rCadeGaming]

Do you have the latest MAME with HLSL?  That'll give you the best approximation of scanlines and such.

[mamenewb100]

Do you have the latest MAME with HLSL?  That'll give you the best approximation of scanlines and such.

I believe I have MAME .146, which is not the latest but close.

I did some further tuning with the HLSL program and I gotta say.. I now know what 15Khz is supposed to look like. Once I got the proper mix of scanline darkness and brightness, it now looks decidedly better than my original 32 Khz setup. The picture isn't as crystal clear having the scanlines but I understand the games were not designed that way. Plus it just adds a nostalgic cool factor.

It makes sense that the programmers designed the games graphics around the scanlines being there. They help hide graphical imperfections and smooth out jagged pixels. The animations seem more fluid as well. If you compare this new TMNT photo with scanline effect to the original one I posted without it, you can tell it looks fuzzier up close but the jagged pixels are nearly gone. I guess that is the graphical tricks they used to get the most out of the 'ol arcade monitors.

[rCadeGaming]

Anything new enough to have HLSL should be fine I think.

Mmm... the second picture looks like an improvement, but not close to a real 15kHz tube.  I'm pretty sure HLSL can get you a lot closer than that.

Scroll down to "bashfuldouche's" post here:

http://www.mameworld.info/ubbthreads/showflat.php?Cat=&Number=255547&page=&view=&sb=5&o=&fpart=2&vc=1&new=

I think that might be the best I've seen; really nice.

[mamenewb100]

I put in the settings for hlsl from the link you provided. At first the settings seemed strange because the colors were much different. Apparently the default color settings for MAME are way off? Major difference in Street Fighter and title screen of tmnt. Seems the pixels are smoother too.

Is there any good CRT monitor adjustment programs out there to fine tune contrast/brightness and color? I Googled but didn't come up with anything specific.

[rCadeGaming]

Well, different monitor need different settings.  Those are probably a good starting point, but you could tweak them for your monitor.

All you really need to calibrate a monitor is a good selection of test patterns.  You should adjust brightness and contrast using a greyscale pattern first, then color.  Try googling how to set brightness/contrast with a pattern. 

Here's what I do for color now, just a method that's been working well for me:  You'll need good examples (in-game, or in a test pattern, it's best to confirm with both) of what's intended to be pure red, yellow, and white.  First, adjust the red level so that red areas are nice and vibrant, but not over-saturated.  Just set this to your own preference; you'll see that it's too much when you see red pixels bleeding a lot from where they're supposed to be.  Once red itself is locked in, then look at yellow, which is only affected by red and green.  Move your green level around until you have pure yellow.  If green is too high, yellow will have a green tint, and if it's too low, it will have an orange tint.  Once red and green are both correct, look at white, which is contains red, green, and blue.  Again, move blue around you have pure white.  Too much blue causes a "cool" blue tint, and too little causes a "warm" red/yellowish tint.

Since the HLSL effect will offset all of this, it's best to just do this while it's running to account for it.  Luckily a lot of arcade games have patterns built into the test menu, or accessible with a dip switch.  Street Fighter definitely does, and I think TMNT does too.

The other thing is that I'm thinking is that your clarity and scanline effects, etc., probably look a lot better in real life than in your pics.  Try taking a higher res pic, or more of a close-up.

[Gray_Area]

I think they both look great. Regardless, good lines are better than no lines.

You don't really know until you see a 15khz tube running at say 224x256, as the physical element gives a certain dimension. It also depends on what kind of tube you're trying to emulate: early 19", 25 and 27", later model 19. They all have specific phosphor designs and dot pitches.

[mamenewb100]

Found out that the setting I used were only designed for certain games. Street Fighter looks AMAZING. The colors are more rich and everything is sharper. Seems to be almost arcade perfect. TMNT looks pretty good too. However games like Golden Tee, the colors are way off and too dark. Guess I'll need to dig around any find settings for specific games or spend allot of time trying to get it right myself.

I guess it's not that the colors are off in MAME, it's that they use universal settings that look decent on all the games but not quite right for specific games until you tweak it for them. What I see on the monitor in real life is definitely better than what shows up in the pictures I take. Thanks allot everyone that helped out. Think I have a good starting point.

[rCadeGaming]

 

[mamenewb100]

Hate to bump this thread but wanted to show the final results of comparing scanline effect vs. original 31K image. Can't believe how much it smoothed up the jagged edges and color difference. Top is scanline effect and bottom is original 32K.

[Jack Burton]

I wonder, is possible you could send double refresh modes to a VGA arcade monitor to get a 240p picture? 

Since it supports 31khz at 60hz, it should theoretically be able to handle 240p at 120hz right?  Unless it just gives an "out of range" message to anything that isn't within a narrow spec.

[rCadeGaming]

It should work because 320x240p@120Hz is 31kHz.  This works with some CRT PC monitors, but some will not attempt to display because the protection doesn't recognize it.  You also have to be outputting this from the PC, so you'll need a graphics card that can handle a custom modeline like that.

One thing is that even if it does work, it will look oversharp because a 31kHz monitor generally has a much finer dot pitch than a 15kHz.

[mamenewb100]

One thing is that even if it does work, it will look oversharp because a 31kHz monitor generally has a much finer dot pitch than a 15kHz.

It has a 0.73mm dot pitch. Most CGA arcade monitors I've looked at are 0.79mm. So while it wouldn't look Perfect, it would be darn close I would think.

My video card uses Calamity's drivers which should be able to get low resolutions. Maybe I could modify a resolution in Arcade OSD to force a high refresh? I don't know how to do it and don't see any info on how it could be achieved though.

[rCadeGaming]

Yes, dot pitch there sounds fine.

I'm waiting for the newest GroovyMAME to come out (it will work with user defined modelines) before switching to an ATI card and CRT_Emudriver/ArcadeOSD etc.  I'm using a nVidia+Soft15kHz+Powerstrip for native res right now, so I don't know how you'd do that with CRT_Emudriver yet.

[Gray_Area]

It should work because 320x240p@120Hz is 31kHz. 

I'm surprised MonMotha hasn't chimed in on this. If the monitor specs say 60hz, then no it won't.

[mamenewb100]

It should work because 320x240p@120Hz is 31kHz. 

I'm surprised MonMotha hasn't chimed in on this. If the monitor specs say 60hz, then no it won't.

Actually I'm amazed that it DID work. I've posted about it in the Groovymame forums. Even though the Makvision manual states that it only supports 47-90 Hz, it displays perfectly fine at 120 Hz with scanlines. Only Linux has produced proper scanlines so far though. I doesn't sound like it pushes the monitor anymore than 60 Hz but time will tell I guess. It looks great on the classics.

I guess some 31K arcade monitors will reject high refresh rates but luckily this Makvision model does not.

[rCadeGaming]

The manual is probably referring to the vertical scan rate it can support with more common 31kHz resolutions, which couldn't go over 90Hz without taking the horizontal scan rate too far beyond 31kHz.

Where is your post in the GroovyMAME section?

[mamenewb100]

Where is your post in the GroovyMAME section?

It's actually in the GroovyArcade Linux sticky post of the GroovyMame Section. I originally tried it in Linux. It looked crummy in windows but I might need to have different settings.

Anyways these pics probably look much closer to a regular 15K monitor.

[mdrejhon]

I wonder, is possible you could send double refresh modes to a VGA arcade monitor to get a 240p picture? 

Since it supports 31khz at 60hz, it should theoretically be able to handle 240p at 120hz right?  Unless it just gives an "out of range" message to anything that isn't within a narrow spec.

That's correct. 
And you can also use black frame insertion to black out every other refresh with a black frame...
...so you CAN get the perfect 240p 60Hz look on 31.5Khz monitors! 
This allows you to keep 480p authenticity _AND_ keep 240p authenticity!

This was recently done with an experimental MAME black frame insertion patch, for 120 Hz LCD's:
www.blurbusters.com/mame

There is also a thread about the new black frame insertion modification for 120 Hz MAME...
...Success reports for both 120 Hz LCD and 120 Hz CRT!   Calamity confirms success on his 31.5Khz monitor.

NOTE: In addition to being good for 31.5 Khz monitors, it is also good for 120 Hz LightBoost LCD users, with the LightBoost stroboscopic backlight (HOWTO), combining this with HLSL -- you're now even more complete with CRT flicker and CRT zero motion blur.  Only the black levels seem off (not as black as CRT black).

[Gray_Area]

Wow, far out.

[rCadeGaming]

Nice.  The latest screens look very good to me, and I'm unreasonably picky!  Huge improvement.

[MonMotha]

A lot of PC monitors can handle 120Hz refresh, and 240p120 is indeed ~31kHz, right at the bottom of the horizontal scanrate range most PC monitors are designed for.  120Hz support on arcade monitors seems rarer, but I've definitely seen it in specs.

The comment about it looking oversharp is spot on, though.  The dot pitch on PC CRTs (M series tubes) is usually much much finer than those found on TV tubes used in arcade monitors (A series, or, if you've got a crummy monitor, B series).  It varies, of course.  Some old PC monitors had relatively coarse dot pitch.  The again, they also often supported 15kHz scanrates.

[Jack Burton]

Where is your post in the GroovyMAME section?

It's actually in the GroovyArcade Linux sticky post of the GroovyMame Section. I originally tried it in Linux. It looked crummy in windows but I might need to have different settings.

Anyways these pics probably look much closer to a regular 15K monitor.

So I take it the Makvision was able to accept 240p@120hz?  So you've got hardware scanlines now and a pixel perfect image?

   I was just throwing that out there as a crazy idea. 

[MonMotha]

240p120 won't be quite "authentic", but it'll be really close.  The flicker won't be right.  You may be able to get somewhat close by blanking every other frame and turning up the contrast on the monitor a bit high (your desktop will be over-bright).  Some experimentation may be in order, but I suspect this is probably your best option for old-school emulated video on a 31k arcade monitor.

[mdrejhon]

One huge advantage of 120Hz is the reduction of input lag.
VERY important for authenticity on button-mash and fast-twitch games, because MAME hurts some authenticity by the forced input lag caused by framebuffering the graphics....

Also, when will black-frame insertion become an official feature built into MAME?
People have reported that it actually makes 240p 120Hz practically indistinguishable to the look of 240p 60Hz on a 15.5Khz CRT (for the same dot pitch/beam spot size).  And you instead get a net increase in authenticity (compared to 15.5Khz CRT), because of reduction of MAME-forced input lag...

Historically MAME adds a bit of input lag compared to original machines, because MAME needs to create a framebuffer before outputting to the display.   So you get a minimum added +16.7ms input lag (1/60second).   One big improvement that 120Hz provides, is the large reduction in input lag, down to only 8.3ms.   This creates a big improvement in games such as Street Fighter.

There are two ways to run MAME at 120Hz:
-- Use a 31.5Khz arcade CRT, running at 240p @ 120Hz
-- Use a desktop CRT supporting 120Hz
-- Use a 120Hz LCD

However, to eliminate the double-frame effect at 120Hz, you need to add black-frame insertion (black frames between refreshes), which keeps the 60Hz CRT style effect at 120Hz.  It also reduces motion blur on LCD's -- see http://www.blurbusters.com/mame/

When will black-frame insertion become an official feature of the main MAME source code tree?

Source code diff by cpharlock: http://db.tt/linhVuTQ
Compiled MAME 0.148: http://db.tt/jOknzHEU
Command Line:  mame.exe romname -nomultithreading -nothrottle -video d3d -syncrefresh -strobe

This allows you to the reduced input lag on 120Hz displays, and you also get to keep the authentic 60Hz flicker / eliminate motion blur / eliminate double image effect on 31.5Khz CRT.

If it's now officially added to GroovyMame, which version (link please), and which command line options?
The MAME page on Blur Busters will need to be updated for that.

[jdubs]

I haven't seen a listing of what CRTs are capable of 120hz 240p.  Which ones will do it? 

-Jim

[Rigby]

I haven't seen a listing of what CRTs are capable of 120hz 240p.  Which ones will do it? 

-Jim

some CRT computer monitors will.