|Reader Reports Noise in Display
using DVIator ADC Display Adapter|
(Some noted the issue with ADC extension cables also)
Last Updated: 2/12/2002 for more owner reports
|Yesterday's news (Feb. 11th) had another reader report of "Noise" in the display from users of Dr.Bott's DVIator. The first note on this from a reader is in an update to last summer's Apple 17" LCD review
here. Here's the reader comments on this issue noted in the Feb. 11th news page. (See below for many other reader comments, some noting the issue with ADC extension cables also.)
I assist in building Digital Video Mac at an Apple Reseller here in Melbourne, and today we experienced disapointing problems with the Dr. Bott DVIator connector.
There appeared to be 'noise' of some sought, small light-green pixels where evident patches where dark colours were being drawn.
The best way to describe it would be looking at a (green) star twinkling as it's light passed through our atmosphere etc...
Resizing the image, (A dark red mountain bike frame against a white background) did not remove the noise and the noise was also scaling (hence moving) with proportion to the dark coloured regions of the image. Light or white pixels being drawn are not affected.
We tried two Dviators and both showed the effects.
So onto Hardware:
MacOS 9.2.2 (Default factory install with items like WebSharing, Speech etc disabled)
Dual 1Ghz, 1.5Gb RAM, 80Gb stock with an extra 30Gb drive also.
GForce4MX in AGP and a PCI Mac Voodoo5500 (64Mb card with DVI & VGA ports) Video cards.
PCI IGNITER SDI (serial digital interface) DV card (drivers had not been installed as yet)
The GForce4MX has a 17" Apple ADC monitor connected using the ADC port on the Nvidia card. This runs perfectly of course but 17" ADC displays are not currently compatible with the Dviator (as officially mentioned in the box also) [I assume he means the 17" CRT ADC display, not the 17" LCD display. -Mike]
The Voodoo5500 is running a 22" Cinema Display via the Dviator adapter.
I immediately thought the memory was faulty on the Voodoo5500, but shutting down and connecting a VGA 17" screen displayed all images as expected without any comparible 'noise'.
I using the 1.13b Voodoo5500 drivers for the Voodoo5500.
I used both the OpenGL 1.2.4 drivers 1.2.1 OpenGL and experienced the same 'noise' problem. [OpenGL 1.2.2 and later I think has issues with the Voodoo5 based on some past reports, but this is not a 3D driver issue as it appears in the 2d/desktop image.-Mike]
The 22" Cinema display worked as expected when connected directly via ADC.
After looking at the www.drbott.com web site, there does not appear to be a CPG (compatible peripherals guide) other than quoting standards of DVI (Other computers or video cards with a DVI connector must provide support for Apple ADC flat panel displays in their firmware or drivers. If in doubt please ask the manufacturer of the video card.)
Tomorrow we shall attempt to connect the 17" ADC to the DVIatior using MacOS 9.1 and/or 9.2.2 with 9.1 video drivers and see if the noise is replicated on the 17".
I thought I'd better pass this onto to you as I bought my voodoo5500 with the intention of using an Apple ADC monitor (while 3dfx were still around anyway) in the near future. Admittedly the voodoo5500 is not (yet) supported in OSX, but this may however affect current user purchasing still using MacOS9.
Again this noise issue with the DVIator has been reported before here even with other brands of video cards such as the ATI Radeon PCI. (I guessed it may be noise on the cabling perhaps from the external Power supply of the DVIator.) It may not be a problem for all owners. (See below for later reports in reply to this posting.)
If any other readers have seen this issue or have solved it, let me know. (I also suggested he write Dr.Bott about the problem, since it does not appear to be specific to just one type/brand of video card.)
Other Owner Comments: Here's a listing of reader replies to this posting (most recent first). There's also some comments from owners of ADC extension cables also noting pixel noise/artifacts.
Just a quick comment on the DVIator 'noise' problem - I've seen this too,
setting up a DV editing system with two 22 inch ACDs. The strange thing is
that switching the displays over got rid of the problem completely (i.e. the
one which was running off the ADC port went onto the DVIator and vice
versa)- so it must have at least something to do with the characteristics of
the particular ACD unit you are using. Really bizarre.
i own the dp800 with twinview and 17" LCD.
i have the same problem.
on mine, the green twinkles only happen on the left side of the screen.
certain images with shades of grey causes this problem.
if i drag the image across the screen, the green twinkles does not exist on the right side of the screen, weird.
this problem exists in os9 and osx.
i can magnify it and the green dots gets bigger. that tells me that it is not a problem with the monitor.
i think it's either device driver of bad memory on the video card.
the twinkle correlates with mouse movement. i move the mouse, it twinkles.
I had a big problem with the Dr.bott ADC extension. My Apple 17" LCD shows
red snow and noise when attached to a G4 dual 1ghz, Nivia MX 4. With the
extension cable removed everything is fine.
I have the same problem with the Dr.Bott ADC extension cable (not the DVIator). I wanted to connect my brand new dual 1 GHz G4 via ADC extension cable to my wonderful Cinema display an was shocked about the noise in blue and green colours. When I plugged the Cinema connector directly to the ADC port of the Mac everything was OK. Then I tried my Cube with the ADC extension cable and that was peferct too. So I thought it must be the Gforce 4MX grafic card. Even the ATI card of my Cube worked in the G4 when I connected it to the Cinema display via the Dr.Bott cable.
I«ll try to get an older Radeon card, which I hope will work in my configuration. I«m not a gamer and so this could be a solution for me, although it«s sad that there seems to be such a incompatibility between this lightning fast graphic card and the ADC extension cable.
there is definitely an issue with the DVIator and highres-LCDisplays.
i've purchased the DVIator because i wanted to use my cinema-display
together with my windows-pc too. the manufacturer (dr. bott) recommends
using the ELSA Gladiac 511 DVI. using this card, i also had these green
flickering pixels. okay, i've tried an ATI Radeon VE (OEM, using an ati
chip, but manufactured by some taiwanese company) it got worse, this
card produced horizontal, black lines... the next card i tried was a
matrox g550. nothing, this card did not work at all. (dr. bott writes on
it's web-site that this card isn't supported) i don't like fans on my
graphics-cards, so the ATI Radeon 7500 [PC] was not an option for me.
although it is not longer manufactured, i was able to buy a retail ATI
Radeon VE Dual-Display. this one works almost flawless, even though i'm
able to see some (let's say 5 at the maximum) green flickering pixels in
connecting the cinema-display via ADC to my cube
using an ATI Rage 128, an ATi Radeon or the NVidia Geforce 2MX works
perfect, not a single faulty pixel! connecting my 15" studio-display ADC
using the DVIator to all of these cards worked without any problems. i
suspect there's a problem with the bandwith or signal-strength of the
TMDS-chips on these graphic-cards. (using a DVI-to-VGA-adaptor, i've
switched over to an analog-crt-monitor on the fly, and there, the
picture was perfect at 1600x1024; on the ELSA's DVI-connector, the
analog signal is also active when driving a digital-lcd). gefen states
on their web-site that "other" DVI-to-ADC-converters have "some pixel
loss". now i know what they mean, knowing what i know now about
DVI-to-ADC-conversion, i would suggest to buy gefen's ACTIVE DVI-to-ADC
As a FYI, even without any adapter, using a DVI Cinema display (original model)
I saw horrible noise with an early Hercules Geforce2 GTS card using the DVI port.
Replacing the card with a Gainward CardExpert III (GeForce3) worked flawlessly
(even DOS support). I noted this last year in an update to the original
DVI Cinema display review here on the Video articles page.
The timing of your article couldn't be better -- I've been researching my
options for connecting an Apple 17" LCD monitor to my Beige G3. I noticed
the earlier article on your site that mentioned "pixel noise" and I found
this other DVI --> ADC converter:
[Note: I noted the GeFen adapter last year in the news page, it
was the first adapter available. It's still linked in the FAQ's displays/monitors
It costs around $199, but claims to have no "pixel loss". The extra $50
compared to Dr Bott's DVIator seems worth it. Why spend $999 on a
monitor, and another $150 on a DVI --> ADC converter, only to have
artifacts visible on screen?
I'm planning to use an ATI Radeon PCI card but I don't own one yet.
Thanks again for the great info!
I just got a Formac 1640 flat panel and had to go through the excercise of
learning about ADC to
DVI adapters. I was very concerned about the passive nature of the DVIator
solution. Signal quality
can degrade and noise can be picked up by the cable. I looked around and
found the Gefen (www.gefen.com) DVI-to-ADC box. It was on sale for the same
price as the DVIator and it
offers much more functionality - it's an active signal enhancement and cable
extender box as well
as a converter. The images through this device are flawless and there is
plenty of cable length to
move things around and not crowd the connectors on the back of my tower
It appears that the DVI-to-ADC has returned to it's normal $199 price.
However I strongly suggest
the users requiring a DVI to ADC converter consider this device, especially
if they are having imaging
problems with the DVIator.
As you may recall I had this cinema display issue - my solution? Sell the cinema, bought a 20" viewsonic panel. Now I have more desktop and a built in A/B switch so I can use both my PC and Mac at the same time. Nice bonuses-1600x1200 instead of that goofy 1600x1024, and it pivots on the PC.
As far as the shimmering itself, the problem was only evident on the Mac. When I hooked up the DVIator to the PC's nVidia card all was fine - mac, always shimmered.
The best ways to demonstrate the shimmer, turn on the screen saver that shows the apple logo and XXX's Macintosh flies around - look at logo. I also had a high concentration of shimmers while in IE, and going to www.macosxhints.com. Whatever it is about the color combo of that page - it just danced!
Please keep this issue in the forefront as I'd like to get that new cinema display we've all been hearing about.
I'm using a Studio Display 17" with the diviator and a Radeon PCI card. I
see those green "Sprinkles" too. Sometimes really anoying! :-(
In response to DVIator noise problems:
I bought a 22" Cinema Display, and picked up the DVIator to use the display on my Dual G4 500MHz with an ATi Radeon Retail Card. I saw the "noise" in all of the darker areas on the display, particularly noticeable in apps that display pictures (such as the slide show screen saver in OS X) as well as DV apps like Final Cut Pro and games like Quake 3. I experienced it in both Mac OS 9 and Mac OS X. When the cinema display was connected to the stock Rage128 ADC card, no noise.
After extensive online research (there is even a thread about this very issue on Apple's Support site) including trying other Macs and other video cards, I concluded that it's inherent to the DVIator. I've shelved the DVIator, and put a GeForce2 MX with ADC Connector that I found on Ebay in my Mac. Of course, if you want to use a PCI card with an ADC display, this is not an option.
I'm sure "not me" letters may not be too helpful, but just to defend the DVIator... I've got one on an ATI Radeon PCI card and a 17" LCD studio display. Not a single artifact. Looks every bit as good at a second 17" LCD studio display attached to the ADC port on my GeForce 3.
Just to let you know that I don't have information on the DVIator noice
issue, but I did have to return two ADC extension cables purchased from
Dr. Bott in December 2002.
I connected the original, and the replacement to a G4/733 ADC running a
22 inch Cinema Display.
"Noise" consisting of sparkling pixels that were various colors appeared
in saturated black areas of the screen.
The replacement cable exhibit similar, albeit slightly less noise, but
the overall problem remained and was unacceptable.
BTW, it took three telephone calls and nearly a month to get my credit
card payment refunded.
Take care, and thanks for a great site.
Just thought I would let you know that the DVIator replacement had no
effect, so it must be a problem with either the display or the video
card. I'll keep trying...
(Andy was the first reader to report this problem last year
as an update to the Apple 17" LCD review here.)
Other Video/Display Related Articles:
See the Video articles page for other display/graphics card related articles and reviews. The FAQ has topic areas on Displays/Monitors and Video cards also.
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