Clone output / two screens at once?

[Paradroid]

During my upcoming holidays I need to cull the majority of the SCART TVs that I've collected over the past 6 months and get my collection down to 2 or 3 choice specimens. Right now, I have 14 televisions in the house. While she's supportive of my hobby, I can tell my girlfriend isn't gonna put up with the mess for much longer.

For interests sake, I'll really like to compare some of the TVs side-by-side by running MAME on both screens simultaneously. I'm wondering if someone can tell me if this is possible or not using GroovyMAME and the CRT_Emu drivers. I'm happy to chase up an extra or different video cards if I need to (really, some of these old ATI cards are so cheap that I don't understand why everyone who's into emulation isn't running one).

Any advice would be most appreciated!

[Calamity]

I'm highly interested in seeing if you can get the clone mode working. Your experiment might help me testing this.

Check this thread first:
http://forum.arcadecontrols.com/index.php?topic=116531.0

I used to recommended against the clone mode because in my experience it made vsync not possible for the secondary monitor, as this mode somewhat links both devices in a lowest common denominator way or something, but this was true when using a LCD as the first monitor.

However, I've no experience trying the same thing with two equal CRT devices attached.

Let me know if you have problems getting video on the secondary device.

[Paradroid]

However, I've no experience trying the same thing with two equal CRT devices attached.

Cool. I'd interpret your post as a "might work, not 100% sure" and give it a go over the Summer holidays (which are imminent).

In particular, I'll like to compare my 2 Loewe CT1170s before I sell off one of them. I also scored promising Blaupunkts this week: an IS 70-33 VT and an IS 70-33 VTN. The only difference seems to be that the VTN has an extra SCART port. Really cool looking units and they definitely display the problem games (R-Type, Mortal Kombat, et al) with all lines intact. Haven't had time to inspect fully as I only got hold of them in the last 48 hours. So, as you might imagine, I'm keen to do a shootout and only keep the winning units.

I'll keep you posted.

[apfelanni]

i would advise against cheap y cable solutions . they are dampening the signal , no matter if its scart 15 k or vga input via sub d . u d better set up a second sytem , switch manually with a 1:1 wired scart switcher or buy a professional device , like they used in tv shops to multidisplay a video signal . maybe u ll find some cheap china stuff with sub d inputs on ebay . i think i saw something like an active splitter with 1>2 15 pin sub d and build in signal booster for build into a computer slot some time ago. there are also several external devices on the market. google vga splitter and check ebay .

http://www.lindy.de/s-vga-splitter-intern-2-port/32407.html
http://www.lindy.de/vga-splitter-pro-2-port/32571.html
http://www.ebay.de/itm/220827168696?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2648

dunno how they handle the mamescart thing.

for clean scart signal switching i d recommend something like this ( or a cheap oldstyle fully wired manual sub d switch )  :
http://www.amazon.de/Hama-00042957-Scart-Switchbox-4-1/dp/B00006JAT6

[Paradroid]

Comprehensive advice as always, apfelanni. Thanks!

You've given me plenty of options to consider there. I was hoping to get dual displays going using an ATI card with dual VGA outputs. The X300 I have only has VGA and S-Video so I can't use that. I'll need to buy another card but I'm considering building a new, smaller, dedicated MAME computer and using a low profile card to I'm a little undecided at the moment. I'm going to try the dual output route first and then I'll investigate the other options you provided if it doesn't work.

Thanks again!

[Nephasth]

I've got two 19" Wells Gardner arcade monitors displaying the same image for my Two-Headed Beast project. I'm using an ArcadeVGA card with a ~$2 VGA splitter cable (like this) to send the signal to both monitors. Works great!

[Paradroid]

Hmm. For that measly price I might just give it a go. Only a few bucks at stake. Thanks!

[blagger]

I have a cheap  ATI 9600 card with dual VGA output and two scart CRT connected.
I am running the soft15 patch and I have an excellent picture on both outputs using clone mode.
I would be very interested if you can run the clone mode with Calamity's drivers.

[Paradroid]

Again, good to hear another success story!

As well as a VGA splitter, I ordered an ATI X1300 card with dual VGA output. The seller is in the same city as me so hopefully it'll get to me quickly and I can get stuck into this.

I'm really interested to see two CRTs running an identical picture side-by-side for testing purposes. I think that will be the best way to confidently determine differences in image quality.

[Paradroid]

Well, this took me a while but I can finally report back on my experience!

I bought a dual output ATI X1300 a while ago that came with a twin VGA cable. This caused me a fair bit of grief as it took me an age to get the drivers to install correctly. Then, after about an hour of work, it didn't want to show many of the modes I fed it. I'm assuming that this particular card had issues with low dotclocks? Either way, very frustrating.

A while after that the VGA splitter I ordered from China arrived. This cost me a couple bucks and it looked nice enough... but I couldn't even get a single display to work with this cable let alone 2.

Tonight, as I was getting ready to wind down I remembered I hadn't checked the letter box. I went down the drive a found a package waiting for me! Ripped it open and it was a dual output X300 that I bought on eBay recently. A low profile model so I had to take the bracket off to stick it in my desktop.

Fired it up, re-installed the 9.3 drivers. Then, I lugged another TV into my room and hooked everything. Opened up CCC and chose "Clone desktop 1". Turned both screens on... BINGO! It worked!

I have to say, this looks really cool in action! Something about seeing multiple screens with simultaneous moving images... mesmerizing.

This has got to be the ultimate way to compare monitors: it's so easy to spot the differences in quality when they're running side-by-side. If I got the screens level on the same workbench it would be even easier. Already I could sense that testing screens one at a time (for image quality) has been tricking me: the individual differences between the Blaupunkt and Loewe I had setup where obvious when seen side by side yet the overall quality of each was less pronounced than I had expected.

So, it's confirmed: CRT_EmuDriver and GroovyMAME can be used with a dual output video card with two CRTs attached.

[Calamity]

That's AWESOME!

So did you notice any issue regarding v-sync for some of the devices. Probably not as they're both displays of the same kind. This is something I had never tested, it's cool that it works.

As for the X1300, yes, I'm afraid it's one of the cards that doesn't support low dotclocks.

[Paradroid]

So did you notice any issue regarding v-sync for some of the devices.

I only did a quick test (last thing before bedtime) but both monitors were exhibiting the same, silky smooth GroovyMAME scrolling I would expect. I didn't notice any sync issues with either display.

Definitely more to come on this topic as I intend to use this setup for A/B testing.