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Old 24 January 2019, 02:00   #1
Thayer
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15Khz Monitor vs Scandoubler

Hello. I have searched a bit on this and cannot find an answer.

I am wondering if a scandoubler make a difference compared to my 15Khz monitor for my 1200 and 500. Right now I get some vertical bars, barely visible and the picture isn't the clearest but it works fine. Perfectly passable when playing games but when reading text it is fine but not great. Right now I am using the Dell U2410. I have read fooling around with the pixel clock and timing setting might help but I haven't tried that yet.

I hear stories of scandoublers with super crisp clear pictures using HDMI but I am doubtful and don't want to put out a lot of $ without somebody who has seen the difference. One I was looking at is here:

https://www.ebay.com/itm/Amiga-HDMI-...2/264153232339

Any help is appreciated,
Thanks.
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Old 24 January 2019, 02:40   #2
MartinW
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Do try with the pixel clock as that can certainly help if not entirely eliminate the vertical bars. I recently bought a BenQ BL702A for my machine and adjusting the pixel clock removes 99.9% of any artifacts. The picture becomes about as good as an LCD can get (apart from the viewing angles are pretty poor on this monitor).

My machine has a scan doubler built in so I have the choice between using the BL702A's native 15.75Khz mode, switching off the scan doubler or using the scan doubled mode. There isn't really much difference but because the circuitry for the scan doubler isn't the best and it adds noise (I built it!) I am bypassing the scan doubler and using the 15.75Khz mode for games and stuff and VGA for the RTG modes.

Now, I never paid attention to scan lines on CRT monitors before but I also have a CRT 15.75Khz monitor on my A1200 next to the BenQ and I most certainly take notice of those scan lines now - I really miss them on the BenQ.

So my opinion would be that if you can have scan lines with your scan doubler of choice then that is what I would do - I would use scan doubled with scan lines. Clearly that's a personal preference however.

Another factor will be if the scan doubler and monitor support 50Hz. Hmm, that's if that is even a thing for you in Canada? I don't know if that's a consideration or not but it is in the UK and Europe.
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Old 24 January 2019, 10:53   #3
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Width and pixel clock are crucial here. Some monitors just cannot show every last pixel of the amiga's full overscan, you need to adjust it until the amiga's pixel boundaries fit in line with the monitor's scaler's expectation.

I run my Amiga into a WQHD monitor, I cannot get rid of banding in NTSC modes, but thankfully PAL can be made sharp. My PAL modes have something like 3-4 pixels missing on the right hand side to get rid of that banding. I have compensated that with overscan prefs.
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Old 24 January 2019, 13:22   #4
idrougge
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Quote:
Originally Posted by Thayer View Post
I hear stories of scandoublers with super crisp clear pictures using HDMI but I am doubtful and don't want to put out a lot of $ without somebody who has seen the difference. One I was looking at is here:

https://www.ebay.com/itm/Amiga-HDMI-...2/264153232339
If you see one of those, burn it so it can't hurt anyone else. It makes your Amiga output look like a RealMedia file from 2002.
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Old 25 January 2019, 18:50   #5
Thayer
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Originally Posted by idrougge View Post
If you see one of those, burn it so it can't hurt anyone else. It makes your Amiga output look like a RealMedia file from 2002.
Really? They aren't good at all? I guess theybare OK if you don't happen to have a 15khz monitor handy or if HDMI is your input option but after doing some more research and reading replies here I think I will try the pixel clock settings.

Thanks for the replies all!
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Old 26 January 2019, 03:20   #6
idrougge
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If all you ever do on your Amiga is text processing, it might suffice. For anything that moves, the lag and distortion makes it unusable.

To add insult to injury, those boxes are a 29,99 € card from China housed in a box with an Amiga sticker, marked at a 100 € price.
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Old 26 January 2019, 20:38   #7
Thayer
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Originally Posted by idrougge View Post
If all you ever do on your Amiga is text processing, it might suffice. For anything that moves, the lag and distortion makes it unusable.

To add insult to injury, those boxes are a 29,99 € card from China housed in a box with an Amiga sticker, marked at a 100 € price.
Wow I had no idea (about the board) - I thought this guy made them himself or something. Thanks for the insight.
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Old 27 January 2019, 02:43   #8
dalek
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Yes just google GBS-8200 / GBS-8220.

If you want to try and get a better picture from it start here: https://shmups.system11.org/viewtopic.php?t=52172

But you would be better served getting an LCD that does 15khz natively, or put the money to an OSSC.
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Old 27 January 2019, 20:31   #9
Krashan
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Quote:
Originally Posted by Thayer View Post
I hear stories of scandoublers with super crisp clear pictures using HDMI but I am doubtful




It is possible with Indivision AGA. PAL High Res Laced displayed on FullHD monitor. Amiga pixel grid perfectly locked on monitor pixel grid.
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Old 27 January 2019, 22:49   #10
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Guys, ok the GBS-8200 /8220 out the box is ok for the money. Hell you can get it for £14!

But if your happy / love to tinker & solder you can turn the GBS-8200 into a pretty decent piece of kit.

The thing is, the actual chip they use to do the heavy lifting is good. The components and firmware they stuck on the board is not. However.... There is custom firmware.
The project started off using a Raspberry Pi, now someone else took it over and it uses a <£4 WiFi enabled Arduino.

https://github.com/ramapcsx2/gbs-con...d-the-Hardware

Ok there is some fiddling about, but for the price once modified this KICKS ASS!
It works great with RGB enabled consoles/computers. I fit a female SCART coupler to mine so I can just plug in any system.
On the VGA out you could always add a VGA-HDMI dongle if your digital inclined.
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Old 28 January 2019, 18:17   #11
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ooh, that is good to know! I think that the tiny soldering points is a little beyond my skills though, I will just keep saving up for an OSSC
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