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Discussion Starter · #1 ·
I noticed on Sonys new XBR brochure they talk about Direct Digital Circuitry on page 13 ( http://www.sonystyle.com/intershopro...R_Brochure.pdf ). It looks like some models bypass the internal analog circuitry when you use the DVI input, and some do not (2002 vs 2003 Digital as per the paragraph and diagrams). Does anyone know if the 40XBR800 uses the 2002 style or 2003 style. I would assume 2002 since it was released back then. Any idea if the XBR910's use the 2003 style of direct digital, or just the LCD and Plasma models?
 

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Thanks for posting this link, uzun. This is actually one of the things that's concerned me slightly since the HDCP-DVI saga began. I called Sony to see if they could provide more clarification on this re their CRTs. The first person I spoke to said the DVI input bypasses the analog circuitry on all their TVs... the second wasn't so sure. So they're gonna get back to me.


The DIRECT DIGITAL CIRCUITRY referred to in the PDF seems to relate only to the WEGA flat panel LCD and Plasmas though. It appears to be a part of the WEGA Engine system. If you look on page #15 in the PDF, the CRTs, including the 910, have an N/A (not applicable) indicated for the WEGA Engine system. That's my interpretation anyway.


I'll be curious to hear what Sony says though as well.
 

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Discussion Starter · #3 ·
I think it's unstated as to how non WEGA engine TVs handle digital. If I had to guess I would say the 910 bypass excessive internal analog processing, and the 800's do not bypass extra D/A conversion. It seems clear that last years Plasmas etc also do NOT bypass extra D/A conversion, it seems the 2003 models are the only ones that keep the signal digital longer. I am guessing they use this new design across the board, on CRTs LCDs and Plasmas
 

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Maybe I'll have to eat my words, but the fact that there's a change in DVI implementation on the FPDs doesn't really compel me to believe there'd be a similar change on the CRTs (2 different technologies). Images on the 910 could certainly be sweetened in other ways though.


If either the WEGA Engine system, or Direct Digital Circuitry are listed in the final 910 specs, or if the Color/Chroma Decoders seem to be bypassed (i.e. have no effect) on the DVI signal on the 910, then it might be a very different story.
 

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Discussion Starter · #7 ·
The first link indicate that the 2002 version of the Wega engine is present in the 3 XBR800 models. The last link indicates that the new XBR910's have the 2003 Wega engine. I stand by my first impression, I believe the XBR800's have the Wega engine 2002 version, as described in that brochure. And that the 910s probably have the 2003 version, with respect to processing DVI input. I'm not sure of this, but that's the impression I get from reading the stuff from Sony. I emailed them for a clarification.
 

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Discussion Starter · #8 ·
Sony replied to my email regarding what sort of direct digital circuitry the 40XBR800 uses. They said:


The DVI input of the television goes through the same processing as mentioned bypassing the comb filters and signal processors.


Thank you for the opportunity to be of assistance.


I have to say I'm still dubious. He is suggesting that the 40XBR800's DVI input bypasses the comb filters, chroma decoders etc as per the 2003 diagram on that page. If that's true I wonder what used the 2002 model? Since the XBR800's were the first to even have a DVI port. I kind of think he is mistaken, but who knows for sure?
 

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Discussion Starter · #9 ·
OK, they replied again. I asked if the 40XBR800 uses the 2003 style direct digital circuitry, bypassing the chroma etc. He said:


This is correct for the newly released products of this year.


Thank you for the opportunity to be of assistance.


I have to assume this means the 40XBR800 has the 2002 style DVI input, and the 34XBR910 has the 2003 style more direct digital style. I have emailed them yet again, giving them a chart to fill in requesting which current models use the 2002 style of DVI design and which use the 2003 style. That should clear things up once and for all I hope.
 

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But it's a CRT... it eventually goes to analog processing anyway.


How important could any change really be?
 

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The diagram that uzun referred to indicates that there may be multiple D/A A/D conversions in the internal circuit of some of the pre-2003 Sony TVs. Each of these steps has the potential to further degrade PQ. So the more of them that are eliminated, the better IMO. Based on some of the other links above, Sony is trying to re-design it's circuitry to make improvements along these lines. Even though the CRT may be analog RGB, it would be nice IMO if they could preserve the signal from a DVI input in digital form until it reaches that point, to eliminate as much loss from analog processes, and D/A conversion as possible.


Compared to the 2003s, it looks like some 2002 DVI TVs could be a bit more of a hodge-podge of older analog, and newer digital technologies. If Sony was in a hurry to get their new DVI interface into the mainstream, then it might be possible that they took some shortcuts in their design, and perhaps may not have gotten around to updating all their circuitry to use the digital signal to best advantage before the 2002s hit the streets.


I'm pretty confident that the 2002 Direct Views do not have a Direct Digital Circuit. Just how much analog processing is going on in them, and how much of it can be scrapped/updated for the digital signal though is unclear to me. Based on the replies uzun and I have received from Sony, it sounds as though even some of their "product specialists" may be rather confused on this.


One question which might shed some light on this is-- Do the 2002 DVI XBR Direct-Views have digital or analog chroma decoders?
 

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Somewhere in this forum I remember there being a link to the service manual for the 2002 year DA4 chassis (HiScan).


On page 226 is the block diagram showing that the DVI input(video 7) is one of four sources that feeds into an analog switcher(CXA2151).


The other 3 sources are video5,video6, and the signal converted from one of the non-components inputs(video 1,2,3, or 4).


Page 246 shows the actual DVI connector feeding into a DA converter.


Tt appears that the 2002 DA4 converts the DVI signal at least 2 times more often than would be necessary if the DVI signal was routed directly into the MID processor.


If the XBR910 has this more direct route, along with the 1400 pixel horizontal resolution, then it is a major improvement over XBR800 technology.


Like me, if you bought the XBR800 or HS500, then we can look forward to trading up in about 5 years for the next best thing which will surely be better.
 

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Discussion Starter · #14 ·
Just because the CRT itself is analog, does not mean this doesn't matter for a CRT set. It does. If you keep the signal digital until the last possible moment, and do a single D/A conversion, process the signal as needed then display it, it is optimal. That is what the 2003 diagram indicates. The 2002 diagram shows SEVERAL D/A and A/D conversions internal to the set. This would degrade the quality of the image displayed. It means for these 2002 sets there's no difference internally between the component and DVI inputs. The only difference is you skip D/A conversions in the source device (the device sending the signal to the TV)
 

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Question? depending on the source lets say digital TW cable, the signal is

not all digital it should go thru some D/A-or A/D conversions

before it even hits your digital box, correct? Is there such a thing as a 100

percent digital signal, Satalite, fiber optic or is the signal always converted? does it even matter if you finally get digital, 1 ands 0s then

thats it.
 

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It's also a bit unclear as to whether the diagram of the 2002 vs 2003 DVI circuit refers just to Sony's FPDs, or to all their DVI displays, including Direct-Views.


So another thing I'd be curious to know is: Do 2003 XBR Wega Direct-Views like the KV-34XBR910 use a direct digital circuit from the DVI input which bypasses the Chroma Decoder and other analog processing the way 2003 XBR Wega LCD/Plasmas appear to?
 

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Quote:
Question? depending on the source lets say digital TW cable, the signal is

not all digital it should go thru some D/A-or A/D conversions

before it even hits your digital box, correct? Is there such a thing as a 100

percent digital signal, Satalite, fiber optic or is the signal always converted? does it even matter if you finally get digital, 1 ands 0s then

thats it.
To the best of my knowledge, OTA HD is basically MPEG which is Digital YUV. If you're feeding this to the TV using a DVI HD settop receiver, I can't see any reason why it would need to be converted to analog prior to reaching the TV. If I understand the EIA-861 Specs on the Sony's correctly, it probably has to be converted from Digital YUV to Digital RGB by the HD STB for the HDCP-DVI port to accept it. However if that's done correctly, it should be completely lossless, and hence a purely digital source.


DVI DVD players like the Samsung 931 and Bravo D1 should also be capable of delivering a pure digital signal to the TV. DVDs are also based on MPEG (Digital YUV), and although that may also be converted to Digital RGB by the DVI player as with OTA HD above, once again, if that's done correctly, it ought to be completely lossless.


It seems to me, this is really sort of the whole point for having a digital input in the first place. It wouldn't make much sense to feed analog sources to the TV via the DVI input.
 

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DVI always bypasses the CHROMA DECODER. DVI is already RGB and stays that way even when converted to analog. But in 2002 chassis, this analog RGB passes through the same analog path as the components inputs, with all the same downstream conversions.


Some audio pre-amps allow you to channel the CD input directly to the output bypassing the tone control filters which subtract from the quality.


In the future, when our STB (fed by cable or satellite and/or OTA tuner) does all the selecting and line doubling if required, then the only wire going into our DA4 chassis will be the DVI wire. Our CRT's will operate much like a computer monitor with most of the DA4's fancy circuits wasted.


There is no reason why some electronics whiz kid can't market an adapter allowing the analog output of the TV's internal DVI decoder to feed directly into the analog RGB CRT drive circuits. This is not rocket science, but it would require cutting some circuit etches(after the guaranty expires) and making sure the voltages and sync requirements are respected. I'm sure the results would rival the XBR910 when viewed from a certain minimum distance.


Please don't ask me to develop such a hardware patch.
 

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I won't... for the moment anyway. :D It's certainly an intriguing idea though.

Quote:
DVI always bypasses the CHROMA DECODER.
If the chroma decoder is the same thing that people here refer to as the color decoders, then it doesn't seem as though this is the case on my 34XBR800. The RYR, RYB, GYR, GYB color decoders in the 34XBR800 service menu appear to have the same effect on the picture from the DVI input as they do on video from the TV's other inputs. See the link in my signature for more on this.


Is the chroma decoder something different?
 

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Discussion Starter · #20 ·
From my email's with Sony, as well as some of the other links above it's pretty clear that the 910's DO use the new 2003 style circuitry. All the XBR sets designed for the 2003 model year use that. It appears the XBR800's all use the old 2002 style circuitry, including the LCD RPTV's.
 
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