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Discussion Starter · #1 ·
Not sure where to ask this. I have a Blue Ray player and a DirectTv DVR, both have 6 foot Cat 2 Certified, 1.3 HDMI cables that go into the back of my receiver. The HDMI that comes from the receiver to the TV is 3 foot, 1.3 HDMI. It is not certified as Cat 2 because it has to be at least 4 feet long to "get up to speed" as I was told.


Does this make sense? Does it matter? I am using a 720p TV so it is not an issue now I would imagine, but when I go to 1080p will it be an issue?


Help please.
 

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No, it's bogus. I have to consider it a cop-out caused by the company being unwilling to spend the money to get the cable design certified.


It is true that most short cables are OK, but the use of cheap/inadequate cable manufacturing techniques can be just as detrimental to short cables as to long ones.


p.s. A "standard speed" category 1 cable is supposed to be OK for 720p and 1080i, but will not work for 1080p/60.
 

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Quote:
Originally Posted by Ringfinger /forum/post/18280434


It is not certified as Cat 2 because it has to be at least 4 feet long to "get up to speed" as I was told.

"get up to speed" ?!?

And here I thought that had everything.

It is "Up to speed" before it leaves the source.

Shorter IS ALWAYS better when dealing with high bandwidth data.

Now distance, that's another issue.
 

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Discussion Starter · #4 ·
It is from Monoprice and Monoprice told me exactly what I said.


So, is there anything I need to do if I get a 1080p HDTV? How about now, anything I need to do?
 

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Quote:
Originally Posted by Ringfinger /forum/post/18280434


It is not certified as Cat 2 because it has to be at least 4 feet long to "get up to speed" as I was told.


Does this make sense?

No, it doesn't make any sense whatsoever. If the cable were certified Category 2 at a longer distance, it would automatically be considered certified Category 2 at 3 feet. And no, cables don't "get up to speed," whatever on earth that may mean.


However, unless it's a very badly made cable, it'll handle Category 2 at 3 feet just fine.


Kurt
HDMI Cable at Blue Jeans Cable
 

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Yes, it should (though your system is probably not running 10.2 anyhow--1080p/60 at normal color depth is only about 4.5 Gbps). If it doesn't, you'll know--HDMI cable failure isn't usually subtle at all. If you're not seeing "sparkle" dropouts, all is well.


Kurt
Blue Jeans Cable
 

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Quote:
Originally Posted by Selden Ball /forum/post/18280714


p.s. A "standard speed" category 1 cable is supposed to be OK for 720p and 1080i, but will not work for 1080p/60.

A category 1 cable is guaranteed for 720p and 1080i but likely will also work for 1080p. It just depends upon the cable quality and length.
 

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Discussion Starter · #9 ·
Okay, so I am fine, I see no dropouts and when I upgrade to 1080p tv, no need to change? That whole speed thing seemed fishy to me but you never know. Makes me wonder about Monoprice customer service.
 

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Unfortunately, very few people who sell HDMI cable know the first thing about it. HDMI seems to generate a lot of strange statements like this "coming up to speed" thing--Monoprice has also been known to tell customers that tin plating reduces the skin effect by forcing the current to use the whole conductor (!?), and we've seen other vendors make equally weird statements.


Kurt
Blue Jeans Cable
 

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Can I run a 90 to 100 ft. hdmi cable without using any extenders?


Performance wise will I have issues with this long run?


If I need extenders, what brands or models are out there?
 

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90 to 100 feet is tricky but can be done. It is beyond the range of spec compliance for any passive cable, and at that length all of the things that screw up HDMI signals are in full swing. There's no way to know for sure whether you'll need a booster to extend the signal range or not without first plugging it in to try--it's highly equipment-dependent. We sell our Series-1 cable in 90 and 100 foot lengths, and customers have had excellent results with them, but at those distances there are no real guarantees. What we recommend is that whatever you do, you make sure to try it out "in the open" before you go to all the trouble of making a permanent installation.


Kurt
HDMI Cable at Blue Jeans Cable
 

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Is there an easy 'at home' way to test HDMI signal loss (other than looking for obvious sparkles & drop outs)?


Preparing to move my receiver into a closet - trying out my longer cables before doing so & I think I *might* see a slight degredation w/ ~34' of HDMI cables between devices. My comparison was done w/ HD cable, not any sort of controlled a/b testing so it might just be perception. Would rather measure than doing it by eye though..


wiring chain is:

4 ft BJ S1


or


4ft BJ S1

wall plate jumper ~6"

25ft BJ S1

wall plate jumper ~6"

2 ft Tartan 24ga
 

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"obvious sparkles and dropouts" are the only kind of thing one would see if there's degradation, so while I can't think of any other way to test for signal degradation, there really isn't a better way anyhow. HDMI doesn't fail in subtle ways (e.g., by blurring images, causing ringing or ghosting, losing brightness or color fidelity)--if it's not conspicuously failing, it's working perfectly.


Kurt
Blue Jeans Cable
 

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In addition to what Kurt says is that if the cable is just barely over the cliff and only beginning to fail with very minor sparklies, I've found that it usually occurs in darker image content, rather than brighter content. Why this is I do not understand, but I've always found that where there are sparklies present, it is always a lot more prevalent in dark stuff.


So to test, you want to use the exact components you are going to use (because HDMI/DVI cirtcuitry varies a lot between different devices, and use the highest resolution, refresh rate, and bit-depth possible, and view some content with some dark stuff. I also recommend pausing the image(or looking at a cable box menu or something for instance), because it's super easy to spot sparklies on a still image that can be harder to see with moving content (also don't confuse DLP dither and things like that with sparklies, a paused image is not always entirely still/static on many digital displays).


But as long as there are no obvious degradations like this, you're getting 100% and you should not be concerned.
 

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Quote:
Originally Posted by ChrisWiggles /forum/post/18391011


...where there are sparklies present, it is always a lot more prevalent in dark stuff.

Interesting. I wonder if it is due to the way we perceive a light spot on a dark background v. a dark spot on a light background, or something in the implementation or decoding of TMDS symbols that makes light sparklies more probable. The eight bit color is encoded in a 10 bit TMDS symbol. Most of the 256 color values have two possible 10 bit TMDS symbols, but some only have one. And more than half of the 1024 possible 10 bit TMDS symbols are reserved or forbidden. So there is more than a 50% chance that a corrupted symbol would be one of these. Maybe it has something to do with what happens when one of these is decoded.
 

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Quote:
I wonder if it is due to the way we perceive a light spot on a dark background v. a dark spot on a light background,

I've considered that too, but I don't think this is the case (though certainly it is easier to see white sparklies on a dark background, but I also think that they actually appear there more). I had one time where I had a cable just barely failing, with very subtle sparklies, and at the time I had up a splash screen from an XBOX 360, with a slowly moving background. It's not super bright, but say 30-50% mostly, with kind of a wave thing moving around that is darker. The rest of the background was still dim enough that you'd be able to see sparklies still very easily (compared to say on a brighter white background), but you could watch nearly all the sparklies were heavily contained on the darkest part of the wave, and it followed as the wave moved slowly back and forth on the screen. It was really a stark difference, the brighter portions of the background screen looked just fine, but the darkest highlights of the wave were just lit up with sparklies.


But I don't really understand why this would be the case because it isn't like analog where the signal strength is weaker near black and more susceptible to noise.


I also had one where the cable would worsen significantly over about 1 minute. THAT was a weird one. If I didn't know better, I'd think the cable was heating up or something, it was very strange. Maybe the circuit? Plug it in, fire up the system, and it had very very minor sparklies, stand there not touching anything (cable was securely plugged in, not coming loose or anything) and over about 30-seconds to a minute you could watch the sparklies just get worse and worse then lines, then soon enough just total snow. Super bizarre. Almost weird enough to start making me consider some of the wacky cabling snake-oil and magic gnome claims out there!
 

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Interesting mystery. I have sometimes seen cable failure where the sparkles seem to be concentrated at the left edges of color transitions, as though the display was reading along just fine and then got confused when the color dramatically changed. I can't quite explain that either, though it's atypical behavior and hard to pin down. I did spend some time at CES talking with one of the chipset guys to ask whether any receiving circuits currently on the market can figure out that they've dropped a pixel and then use some sort of interpolation algorithm to replace it--I had wondered whether something like that might result in more pixel loss at edges where the colors of adjacent pixels are widely separated than in evenly-colored areas--and I was told that no existing chipset can do that.


Another thought would be that this is, after all, "transition minimized" differential signalling, and a receiver circuit is more likely to make an error at a transition than when reading consecutive 0s or 1s. It could be that some colors are more dropout-prone than others because they have more transitions.


Kurt
Blue Jeans Cable
 
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