[DanOO00]

I have been reading over this forum for a few weeks now, and KNOW that someone here can answer my newbie question.


I recently bought a Philips 55PP9701 rear projection set, and although I am VERY happy with the image quality (I run my HTPC with dscaler and Dishnetwork as the primary source thru a WinTV401 capture card) I am interested to find out if there is any way to reduce the amount of gain that my screen produces directly in front of the set. I notice that when I move my viewing position away from the center, the image tends to look significantly better. I don't notice as much (for lack of a better term) amplified video noise when viewing the screen from a 45 degree angle. Is this normal? Can I do anything to make the center viewing position look as good as when viewed from the sides? Do I make any sense?


Thanks in advance for any help!


Dan

 

[John Mason]

Performed a physical screen 'adjustment' of my 15-month-old Philips 64PH9905 shortly after setting it up. This involved about 5 magazines slipped under the set to tilt the screen downward, pointing directly at a favorite reclining viewing position about 8 feet away. On my set there's a considerable difference in screen gain when you're directly in front and perpendicular to the set. Stand up and the gain falls off considerably. After performing this adjustment I was able to turn down the brightness a good bit--always a good thing for RPTVs.


The function of the vertical lenses on the lenticular screen is to spread the image and brightness to the sides for viewers. Hadn't noticed the slight video noise reduction until trying it just now; seemed to correspond to the slight fall off in brightness. No idea what's going on here.


I bought an Avia test disc when I got my 9905, plus a CDROM service-manual disc. It's important to set up the contrast and brightness properly, and to make sure you have good RGB convergence using the user patterns, the service adjustments, or the Avia. You'll find numerous tips and Philips-specific adjustments here . My own approach would be to minimize video noise. Turning down the sharpness control might diminish the noise. You should be able to see a wide variation in noise depending on sources (for example, different stations, older broadcast tapes versus live NTSC, and especially good DVDs).


If you're new to large-screen TV, the magnified image makes noise more visible, but it shouldn't be distracting. Noise, usually a high-frequency signal, can be prominent in wide-bandwidth sets such as the Philips line. But bandwidth also allows most of the fine details carried by high-frequency signals to become visible. That is, you may see image details that don't make it onto the screen with other sets. So far, I've only come across one source, live NTSC golf games or other sporting events where over-edge-enhanced field cameras are used, and I have to turn my sharpness control almost off. Images are still very bad.


You might want to investigate how good a job the deinterlacing circuit is doing. I've been happy with the Genesis chip performance in my 9905, but I've noticed that some owners of other Philips models have adapted external line doublers or PCs for the job. Besides browsing forums devoted to Philips HDTVs for opinions on this, you might devise some tests. For example, piping an interlaced DVD signal into the set, which would use the built-in deinterlacer, then piping a progressive DVD signal into the HD inputs. The prog DVD will have better images, especially in notorious 'tough' scenes on certain discs. But the set's built-in deinterlacer shouldn't introduce excessive noise. Similarly, if you notice the video noise is absent from HDTV, where the deinterlacer also isn't employed, that's another clue to consider 'upgrading' your deinterlacing technology. -- John

 

[Gertjan]

You can improve the picture in the center by turning down the contrast is what it sounds like.


You probably can't make the picture look the same in the center as it does on the sides, because it's sort of a result of the lenticular screen. Basically the lenticular screen "aims" the bulk of the light of the picture to the center position, and therefore the sides see a less bright picture.


You could see about replacing the lenticular screen with a different rear projection suitable screen; i've read about people who did that with their RPTVs and claimed to have gotten a better picture. I couldn't point you to where i read that i'm afraid - i thought i had read about it on the Keohi HDTV site , but i just checked and i couldn't find it. Perhaps you can find some info on the Home Theater Spot forum .


Good luck


Gertjan