Some video specialist out there? (cable/component/projector)

[gheba_nsx]

* 29. JULY - I UPDATED THE POST BELOW SINCE IT COULD BE OF INTEREST FOR FUTURE INSTALLATION OF YOUR PROJECTOR *

Since this board has a lot of knowledge... ...

I recently bought an Infocus DLP projector. VERY nice! But projectors, installed on ceiling, need a lot of cable distance... and the quality can go drastically down if no attention is taken.

This is the situation: my progressive scan DVD player has a YUV/Component (3xRCA) output and my projector has only the VGA input that support progressive scan (S-Video is avavilable but of cours eonly interlaced).

Good news here is that the VGA support RGsB (synchro on green,also no need of H & V). This make it is easy to make a cable from the 3xRCA to the 15pin VGA.

I did this for a distance of 7m, the cable works and the result seems good (better than the S-Video cable I was using).

What I used is a cable of type RG 179. Most expert told me that RG 59 is the cable to use but it is IMPOSSIBLE to attach it on the VGA. I agree that for a RCA-RCA cable RG59 is the solution, I know. For VGA you need a miniature cable.

The question:

Does somebody know if RG 179 is degrading my signal over the 7m length for the DVD application in a way that would need further enhancement? Would it be worth doing a RG59-RG59 of 6,5m and a small adapter RG179-VGA or should I live with my solution?

Thanks a lot for the help!

 

[ncdogdoc]

Gheba,

If I am correct, the RG series of cables are for wide bandwidth cable transmissions. What you need is a quality set of Component cables, such as Belkin, Audioquest, Monster, Kimber; then remove the projector end RCA's and solder to your VGA adapter. You could probably find a component to VGA adapter out there somewhere that would make it even easier. This way, distance should not be a big factor (although I do not think the small distances you are referring to will matter much for anything but S-video, which is notoriously weak past 8-10 meters).

I know there are several places stateside that carry this sort of stuff, but do know about Europe. Be sure you are working with 75 Ohm connectors and cables, as that reduces the chance of noise on video only transmissions. HTH.

 

[gheba_nsx]

ncdogdoc, thanks for your answer.

The RG 59 and RG 179 are both coaxial 75 Ohm cables. That is the reason why I considered one of them. Buying a finished Component cable (10m), cut it to 7m and attach a VGA would have been very difficult since high quality cables use RG 59 in most cases anyway... and the problem of the small VGA port would still be there... Furthermore the price for finished cables is 2x the price of DIY (and DIY is quite easy inthis cases) .

The best video cables around are to my knowledge these:

Belden 7712A
Belden 7796A
Belden 7789 A
Van Damme RedSeries

And they are unfortunately RG59...

If I am not mistaken, DVD video fortunately is 27Mhz (sometime oversampled at 54Mhz) also it is not that high.

A RG 59 has in 30 feet and 50 Mhz about 0.8 db attenuation (this is about my case, where the distance is 23 feet).

The RG 179 I used has about 2,5 db attenuation on the same distance, again using DVD video.

Is 2,5 db attenuation noticeable?

 

[gheba_nsx]

No one has an idea? Ok... this time I exagerated with the specificity of the question... I admit it!

 

[gheba_nsx]

This weekend with some more same cable I had, again RG179 (1,8m --> 3 x 60cm also a 2 feet cable) I buiit another smaller component-VGA (gold RCA chinch, 75 ohm, metal VGA port) whose attenuation this time is only 0,3db. This of course excluding soldering that was made anyway very well.

I moved the DVD player below the projector, attached the cable and I used progressive scan mode... the result is only very little better than using the previous 7m cable (10x longer!).

The improvement is only noticeable with a test reference DVD where some very hi-contrast (black/white boxes) have slightly better borders. But it is hard to notice any difference even with these conditions...

Hope this is any help for who is going to install a projector and has fear that over 23 feet of cable is too much. If you use GOOD QUALITY cable it is no problem at all.

 

[Soichiro]

I see you've solved your problem but the smaller RG cable should be fine. I have worked in the video industry for over 30 years. PM me if you have any other questions.

 

[gheba_nsx]

Thanks Soichiro. Yes, the problem was solved (or better, it did not exist, it was more a doubt): there is no difference noticeable between a long cable (23 feet) and a short one (3 feet) when using good coaxial 75 ohm component. And I am quite picky when it comes to audio/video quality...

Anyway, it is amazing how well a small miniature cable as the RG 179 can do!

I will remember to write you in case of future doubts! Thanks!

 

[Tantheman]

In the same boat with my DLP Projector. S-video and VGA Pin connector only.

Tan