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VP-12S2: HDTV via DVI Using 20M FO Cable - WOW!

2302 Views 38 Replies 19 Participants Last post by  JeffGoos, 
T
When I first received my VP-12S2 I tried connecting my Sony HD-200 STB to the DVI input using the 10 ft. cable supplied with the HD-200. I saw a fairly significant difference between the DVI connection and analog component connection. Enough that it was clear I wanted to utilize the DVI connection on a routine basis. Unfortunately, to enable this connection permanently in my setup requires a 50 ft. cable. As I'm sure you all know, DVI isn't reliable at distances over 15 ft with standard copper cable. It seems like one of the best solutions to get around this is fiber optic DVI cables like those offered here:

http://www.dvigear.com/lonlendvicab.html


The manufacturer's site is here:

http://www.ophit.com/eng/index.php


At $760 for a 20M cable this is not an inexpensive solution! However, Kaye Consulting offers a 30 day MBG so I thought I'd give it a try. I received the cable today and connected the HD-200 to the VP-12S2. The optical cable is fairly thin and very pliable, with an orange jacket. One end is marked for the source device and the other for the display, so the cable appears to be unidirectional. When the HD-200 and VP-12S2 were both turned on, I was able to select the "Auto DVI" mode on the HD-200. This syncs the output of the HD-200 to the native resolution of the display device. 720p was automatically selected as the output resolution when Auto DVI was enabled. Interestingly, the VP-12S2 saw the DVI signal from the HD-200 as a PC input, not 720p HDTV. I had to select "RGB" for the DVI System menu item to get a picture. The other 2 choices produced a green tinged, unwatchable picture. The VP-12S2 manual indicates that color space conversion is skipped when the DVI System is set to "RGB". Not sure if this is an issue or not.


Now for the bottom line! The image quality of the DVI connection using this fiber optic cable was INCREDIBLE. There was a LARGE difference between the analog component connection and DVI. The image quality on HDNET and OTA HDTV (NBC) was super-clean and artifact free. The picture was noticeably sharper. The analog connection seemed fuzzy and pixelated in comparison. And I thought the analog connection looked good before! My wife was blown away at how good the picture looked on HDNET. DVI certainly takes HD to another level on the VP-12S2. The PQ seems better over the fiber optic cable than the 10 ft. copper cable that is supplied with the HD-200, but I didn't do a direct A/B comparison. While this cable is an expensive option to overcome the need for a long DVI run, I can confidently say that it works beautifully between the HD-200 and VP-12S2. Please LMK if you have any questions!


Tom
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M
Tom,


Are you saying the optical DVI cable looked better than the 10 ft normal DVI cable?


That seems hard to believe. Unless, you were having some sort of transmission problem, the 10 ft should have worked perfectly. Not to mention any transmission problem would have been fairly obvious with pixel break up type artifacts (i.e. obvious noise).


I would also like to point out that at up to 10m, people shouldn't have any problem with plain-jane DVI cables at normal HDTV resolutions (720p, 1080i which are
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johng
Hi Folks,

A while back, Bob Williams of InFocus commented that InFocus had no probles with using DVI cables longer than 10-feet. Does anyone know what DVI cable he was using, and where is can be found?

Good Viewing,

John G
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T
MrWiggles,


You're probably right that there wasn't a difference between the 10 ft. and 20M cables. As I said above, I didn't directly A/B them so I shouldn't have made that statement. It was late when I wrote that post :) I also looked closely at the InLine cable. It's about $475 street price so definitely cheaper. However, they only claim 1280 x 1024 rez at 50 ft. Also, it's very stiff (according to InLine) and I have some tight conduit to route through. The FO cable supports 1980 x 1024 at 20M. Not an issue now, but I figured I may as well spend the extra $225 and get a cable that could support full 1080p rez for the future. Not to mention that the FO cable is very pliable and easy to work with (but has an ugly orange jacket!). I don't think many on the forum have actually tried this cable (lots of discussion about it, however). Wanted to report that it seems to work great with the S2 at a 20M distance. The only question I have is why the projector is seeing the input signal as a PC rather than 720p HDTV.


Tom
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T
John,


Bob Williams said they had success with DVI cables up to 10M with no problems on the 7200. I believe he said it was due to the design of their DVI input receiver. I assume he was using a standard copper cable. I need a cable at least 16M long, so was certain a copper cable wouldn't work (other than the InLine).


Tom
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johng
Tom,

Thanks very much for the clarifications!

Good Viewing,

JohnG
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M
Quote:
Originally posted by Tom Blake
MrWiggles,


You're probably right that there wasn't a difference between the 10 ft. and 20M cables. As I said above, I didn't directly A/B them so I shouldn't have made that statement. It was late when I wrote that post :) I also looked closely at the InLine cable. It's about $475 street price so definitely cheaper. However, they only claim 1280 x 1024 rez at 50 ft. Also, it's very stiff (according to InLine) and I have some tight conduit to route through. The FO cable supports 1980 x 1024 at 20M. Not an issue now, but I figured I may as well spend the extra $225 and get a cable that could support full 1080p rez for the future. Not to mention that the FO cable is very pliable and easy to work with (but has an ugly orange jacket!). I don't think many on the forum have actually tried this cable (lots of discussion about it, however). Wanted to report that it seems to work great with the S2 at a 20M distance. The only question I have is why the projector is seeing the input signal as a PC rather than 720p HDTV.


Tom
1280 X 1024 X 60Hz > 1920 X 1080 X 30Hz


So if it can do SXGA, 1080i should work fine. (Remember that the 1080 is an interlaced resolution).


Have fun,


-Mr. Wigggles
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T
Hmmmm, good point. I didn't consider the interlaced vs. progressive relationship on the maximum resolution. Maybe I'll try the InLine also, and if I don't see a difference go with the cheaper one. That's assuming I can route it through my conduit. Also the place that has it for $475 for 50 ft. (it lists for approximately $675) was leery of a return since it's a special order. The FO cable has a 30 day MBG, so while more expensive it was safer for a trial experiment. Thanks for your input!


Tom
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T
I've been extolling the virtues of DVI over component (and even RGB) for months now, using my experiences with the Hitachi 5500 as a basis for my judgments. Everyone acted like I was crazy or something, downplaying the possible benefits. Even Tom Stites from JVC seemed to indicate that something must be wrong with my projector if DVI is yielding such superior results (this was in response to my criticisms over the lack of 1:1 pixel mapping on the SX21's DVI port, and that RGB was clearly inferior).


I hope now that someone else has stepped forward, everyone will begin to realize what HTPC'ers have known for quite some time: DVI provides results noticeably superior to analog transmission methods.


Congrats on your discovery Tom, and enjoy your projector :)
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T
thirdkind,


Thanks for the support and glad you agree! As I said above, the difference between DVI and analog component for HDTV distribution to the Marantz S2 was HUGE, in my system. In other threads, Tom Strade and Cinergi have also cited superior performance of the DVI input on the S2 as compared to analog RGB or component. It would be interesting to know if the full panel resolution of the S2 can be addressed by the DVI input. I know that's a shortcoming of many projectors, including the SX21. The S2 did not report the resolution of the DVI input signal it was receiving, just that it was "Computer". Too bad it's so expensive to implement a long DVI run reliably!


Tom
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D
What this now begs for an answer to is why is the fiber optics DVI providing a noticeable difference over the copper solution? If it's the same interface type, then there should be some quantifyable measurements to provide an answer. At over 10' is there a significant enough signal attenuation - this could be due to the materials used (and thus some implementations may measure better than others)? What I have read about in the fiber versus coax digital cable debates is that the fiber optics have less susceptability to EMI and RFI - and this is exascerbated with longer lengths of copper based cables. But there is more to it than that (quality of fiber, termination materials/construction, etc) Maybe the answer lies in noise "pollution" and thus better types of shielding would make the 2 equivalent??


Can't pretend to even venture into the DVI digital i/f versus analog component - much beyond my knowledge base. It may come down to noise contamination, or prevention of, that also provides a clue to the potentially superior technology. Any experts care to jump in here (or is this belong in a different thread/forum?)


Cheers,

dagger


PS. - It's good to hear the real world experiences of users' different cabling configurations.
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T
dagger,


I'm not sure about the technical issues you raised, but this fiber optic DVI cable has a convertor at the transmit end to change the electrical signal to light pulses. There's then another convertor at the receive end to convert the light pulses back to electrical signals for input to the display. The cable consists of 4 optical and 5 copper lines. Pretty slick technology! I assume that by converting the electrical signal to light pulses the DVI signal is then immune to any distance limitations present with copper cable. They claim they can transmit DVI signals reliably up to 100M. Based on my experiments it seems their claims are accurate (at least at 20M). This technology certainly comes at a price, however!


Tom
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M
dagger,


There is absolutely no PQ difference whatsoever between a copper and a fiber DVI connection---as long as the copper cable isn't too long. It is only when the copper cable starts to get too long that the image quality starts to suffer. On my system, this problem manifests itself by green sparkles or "snow" on the image.


I believe that the reasons for the degradation include not only EMI/RFI but also the increased capacitance and resistance of longer cables, which causes high-frequency attenuation. Yes some cables do better than others, and some DVI transmitters/receivers are better than others, but I still think that anything over 10 feet is case-by-case. When we renovate the family room, I plan on installing one of these fiber-optic beauties.


Do keep in mind that the data rates are very large on DVI. We're talking about 4Gb/sec max on a single-link connection, divided evenly over 3 channels---1.33Gb/sec per channel. And that's after the 20% signal overhead has been removed. Neither Firewire nor Gigabit Ethernet can come close. In fact, I believe that Firewire's new 3200Gb/sec spec is first going to be fiber-optic only. So it shouldn't surprise anyone that DVI can't go long distances.
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D
Tom, didn't realize this was a real fiber optic product - it comes with active signal converters/amplifiers. It is likely that this is also using "real" glass based fibers (versus the much cheaper plastic based fiber in the Toslink cables), and that material is much more expensive. What's next - DWDM for Terabit transmission interfaces for our PJ's????? Well, with that technology, I believe in the long distance claims - very good stuff indeed.


dagger
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T
dagger,


Yes, it's a very impressive cable technically and certainly seems to work! I've dropped $700+ on audio cables without a second thought in the past. Guess I shouldn't feel too bad about paying $700 for a high-tech cable for carrying digital video at extremely high bandwidths over a distance of 20M.


Tom
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M
The cost of the "glass" fiber is insignificant against the total cost of this product. With the cost of high data rate eletro-optical components dropping like a rock, how long will it be before some projector manufacturer integrates the optical interface directly into the projector?
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DaViD Boulet
Why doesn't someone simply market a wireless digital video transmitter?


It could accept DVI input on one end...and transmit it *wirelessly* to the receiver at the projector which converts the signal back to DVI???


Well? Why not?


It seems it would dramatically simplify the most complicated aspect of front projection systems for many installations.

Quote:
1280 X 1024 X 60Hz > 1920 X 1080 X 30Hz


So if it can do SXGA, 1080i should work fine. (Remember that the 1080 is an interlaced resolution).
What about 1920 x 1080 24 fps progressive? Does DVI support that? How much relative bandwidth does that require?


-dave
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J
at 2002 CES there was a product announced called the Moxi that (I think) was going to be able to wireless transmit HDTV around the house. I just did a quick search and found this link - no mention of wireless. also dont think this thing is going to be on the shelves today or tomorrow.


dont know if my numbers are exactly correct, but I think that a dvi type HD signal would require significantly more bandwidth that is generally available in current consumer wireless systems.

-jeff
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M
ANY one know who is offerng DVI out puts from a DVD source? and from a scaler source?
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T
Immersive with the upcoming aSimilator (combo DVD player/scaler) and Key Digital with the upcoming HD Leeza (scaler only). Acccording to sspears several DVD players with DVI outs will be shown at CES from the likes of Pioneer and Meridian. Also, Theta is planning to offer a DVI out on their Carmen II as an option (SDI is available now). I'd love to see what any of these look like connected to the DVI input on the S2!


Tom
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