colorsignal, single ended or differential

[edison]

He guys i have a question about the colorsignals and what should be accepted as being the standard.

When looking at the ILDA standard the colorsignals are defined as being differential +2.5V and -2.5V but 0-5V is also accepted. Now i looked at several dacs like fiesta.net, Netlase, and qm2000. They all have single ended signal where the negative is connected to ground. To have the best performance and less chance of having distortion it can see diffential is the way to go. The ILDA standard says that diffential is best but even dacs like qm2000 and fiesta that are highend controllers choose single ended 0-5V.


If you design an electronic board what should be accepted as being standard? Should it accept differential signals or not?


Thanks for the help

[colouredmirrorball]

Single ended is the de facto standard. I don't know why as differential would of course have less noise. Maybe it was a choice by some manufacturer to bring cost down? Noise on XY signals is going to be much more visible than noise on colour signals.

I have Norm's Framestreamer which supports differential colour signals. It is the only DAC I know of that does this.

[tribble]

FB3-QS spec sheet says its X-Y is differential, but not the colour channels.

[DZ]

Early QM2K's output differential for color. If you want single ended, connect pins 18, 19 and 20 to pin 25 and that will force the output of pin 5, 6 and 7 to 0-5V. Somewhere along the lines they grounded the - color by default. As far as I know, it's just a matter of changing a few resistors on the higher serial number boards. As far as I can tell there's no real benefit of running differential for color.

[JohnYayas]

It isn't as important with color as it is with your XY. You'll see noise on your XY because your lines will be wiggly. You probably wouldn't be able to see noise in your color modulation.

[edison]

Mmm confusing , We have an ILDA standard but its not totally something that you have to stick to..... That means a manufacturer has to have an differential input but also needs design it so it can handle single ended signals. Great to have a standard when its not totally locked........ The client has to request if he can get single ended or differential output when buying an LD2000. Very convinient.......not.......

Anyway thanks guys for making things more clear

[DZ]

The client has to request if he can get single ended or differential output when buying an LD2000. Very convinient.......not.......

Anyway thanks guys for making things more clear

It's not an option at all, you buy a QM2K you get single ended color. Only early serial number cards were wired for differential. If you wanted differential on a higher serial number card I *think* you can just make a few resistor value changes.

As long as the projector has a differential receiver, it doesn't really matter if the color from the dac is single ended or differential.

[edison]

Ok cool thanks so you could say single ended is the standard now in a way for the colorsignals We did things right then

Totally clear thanks again

[Guido]

Hi Edison,

please plan your Electronics to accept differential Signal then nothing can go wrong.
Also the Easylase I has Single ended Color.
But why Change nearly all to Single ended ? Answer is easy...because the Chinese Guys where not able to wire there Crap correctly.
Much of them left the negative Channels open.
OK, today >95% are single ended. But sometimes, when you use longer ILDA Cables, the lost will be much smaller if all Inputs in your Projector are
differential with high Input Resistance. Adding to OpApms and some R´s could not be the Problem.
I will still go this Way...

[edison]

Thanks for the info, differential input it will be. Already done.

Thanks guys!!!!