[ale] OT: DVI KVM Switches

[aaron]

On Monday 09 January 2006 05:10, Pat Regan wrote:
> aaron wrote:
> > In fact, if anyone reading this can suggest any salient reasons to prefer
> > a DVI digital monitor connection, I'd be interested in hearing
> > (: or seeing :)  them.  
> 
> My favorite reason to use DVI over analog is the fact that I don't have
> to worry about adjusting the sync settings on an LCD panel.

Don't know about that one. The half dozen or so LCD panels I've put into 
service so far needed no local adjustment to function via VGA. Existing 
monitor spec communications with the computers provided the needed
multi-scan options info and set up was true connect & continue.  

>  You also don't have to worry about buying a video card with a high quality
> RAMDAC.  A cheap RAMDAC makes for a blurry picture, especially at high
> resolutions.

... and a less costly DVI monitor could just as easily have substandard (or 
cheap) RAMDAC components.  Moving the RAMDAC element to inside the
monitor case is no guarantee of better price / performance ratios.

> I am assuming he wants to use a DVI KVM on a workstation.  Many analog
> KVMs noticably degrade the signal, especially with longer cable runs (or
> cheap cable).  With DVI you should never have that problem.

I can agree that special cases of long cable runs might make digital 
transmission and DVI monitors preferable. Still, cheap components and cabling 
will screw up digital paths just as easily as analog. My experience in 
transitioning video production studios from analog to digital is that  the 
cost curve on quality digital switching and connectivity components is 
substantially higher than analog due to digital's exponentially higher 
bandwidth requirements in delivering comparable signals.

> I run two 15 inch LCD panels on my home desktop.  In the beginning, I
> had to use an extension to reach from the far monitor to the PC.  You
> could easily tell which one had the extension plugged in.

My analog scenario is a studio system with 2 KVM control stations, one near
the CPU and one on a 30` remote cable run.  We were running Sun 21"
multisync monitors at 1600x1200 (@75hz, I think).   With high quality monitor
cables the images at the two stations were very comparable, despite using a 
budget minded rotary switch KVM selector.  When we later changed over to a 
powered analog RGB-DA, the images were identical. Of course, when we first 
tried the KVM switch setup with a cheap 30' RGB extension, we couldn't get 
enough signal across for the monitor to even make a picture.

> That said, I doubt it makes much difference at low resolutions, as long
> as you set up the sync settings on the LCD properly.  My old panels
> don't auto tune all that well, and usually require a bit of tweaking.
> 
> Pat

I'm still not convinced of substantial reasons for changing over to DVI 
monitor connections. All the issues seem to point back to the inescapable 
need for quality components, cabling and connectors regardless of which form 
of electronic signal you are working with.

peace
aaron