Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems 621, 121 and 421

If the pixel has a different value at one end of the cable then it has at the other end, it is in fact an alteration of the data. Why? Because the delivered data is not intact at the other end.

Digital and analog errors are different in nature; therefore expecting the same manifestations of errors is misguided.


Define "normal" when it comes to HDMI cable lengths. Is that 1m, 2m, 5m, 10m or maybe even 20m? In what I've seen, it is not unusual to have mostly shorter cable runs from sources to a receiver / processor / scaler (1-2m) with one or more longer runs to the display (5m and up). Going beyond 5m (which is not unusual) and HDMI can become quite problematic in my experience.

Me, I'm of the "an error is an error" thinking -- personally I find sparkles and dropouts to be very noticable.





See above, an error is an error and should be avoided regardless of the transmission scheme.


Sparkles are data channel(s) error(s).


Dropouts are typically a DDC channel error.


Timing errors (i.e. jitter).

You could make the argument that there's no visible difference at a given picture size with vs without jitter reduction but you haven't.

John

No one is expecting the same manifestations of errors in digital transmission, and I think we have a firm understanding that the gauge of the wire has a direct relationship to the very obvious errors encountered over a given length of cable. What is in question is how "proprietary active termination, automatic cable equalisation, buffering and de-jittering technology visibly improve image quality, reduce noise and stabilise the video - even on short cable runs," when a device like the 121 is used even when there are no sparkles or dropouts. Rephrased, if I presently don't see any sparkles or dropouts, why would I need a 121? Based on Meridian's comment, even I have something to gain. Are you able to advise what kind of improvements I would experience by adding the 121?

I am running a full bandwidth HDMI 1.3b spec (1080p24 with 7.1 hi-rez sound) home distribution system based around 8x8 Pure Link Pro matrix switcher and Extron 221 (HDMI over a pair of Cat5e/6 extenders).

The longest run in my house is around 125ft in straights cable line and there is no problem whatsoever with getting the full 1080p signal from any of the centrally placed sources, video processors, or blu-ray.

My installer tested all outputs from the Extron extender receivers and there is a perfect HDMI "eye" at the output. All extender receivers are very close to displays (sometimes even directly on the backs of them) which allows for very short runs of HDMI cables: 1ft to 2ft. Even very good HDMI cables are quite cheap at this length.

For everyone who is contemplating runs longer than 20 ft the extender solution is in my opinion the cheapest and most reliable way - the Extron 221 set is around 350$ and decent cat5e/6 cable is by now at commodity prices not even worth mentioning.

One word of warning: initially we tried to use HDMI extenders from Gefen - they where very patchy and unreliable with very, very long time re-establishing "hdcp handshakes" after each switch of a source. We tested Extron and the handshake is nearly instantaneous.

Chenko,

From what I have read, the eye can collapse to a certain point before we experience any difficulties at all. And when that point is reached, the problems are extremely evident. I'd like to know if this is the case or not. I don't think my picture is losing anything, but Meridian says that the 121 is beneficial for short runs. I'd like to know what the device is cleaning up/fixing, and how will de-jittering improve my picture. Does anyone have an answer?

I would ask Meridian about this if I was thinking really hard about something...

As the HD621 has not been released yet, it's hard for anyone to see if it's working as a good HDMI booster as well..

Bad HDMI/DVI cables does definitely impact the image as a whole apart from sparklies. I had one cable which caused sparklies and changing that one it actually felt like the image was more full and relaxed.. I don't know how else to explain it.

Quality boosting can't hurt right?

Well if it's unnecessary it can hurt the wallet! :-)

I own two Oppo HM31s, and I just read that it has a signal equalizer, and they similarly claim, "The signal equalizer is a key component to support long HDMI cables. It removes distortion from the input HDMI signal after it travels over long cables and restores the signal quality/strength." http://www.oppodigital.com/hm31/hm31_support.asp

As with Meridian's claim about the 121, I don't think that this is accurate. How these devices know how to restore data that has been lost or distorted before it reaches it? That doesn't make sense to me.

If I understand HDMI correctly, the problems we see are a result of the signal being too weak, or there being an actual fault in the cable. The malfunctions we see are a result of the TV trying to make due with the poor signal it is receiving - not that there is interference, or actual distortion in the signal. All these signal boosters/equalizers are really doing is restoring the signal to a level that the receiving device can properly decode. I would imagine that a faulty cable cannot be fixed with a booster.

The Oppo runs for $99 compared to $795 for Meridian's 421. The Meridian has some auto switching for a Meridian DVD player, but it also has the buffering and de-jittering. Does no one know how, "proprietary active termination, automatic cable equalisation, buffering and de-jittering technology visibly improve image quality, reduce noise and stabilise the video - even on short cable runs,"?

From the replies posted I am surprised that few people seem to use the 121 and 421; and few seemed aware of the claimed video de-jittering properties.

There does not seem to have been much in the way of evaluating the benefit of video de-jittering. As it is also one of the properties of the HD621 perhaps this can be discussed again soon. We were told that the HD621 was intended to ship by the end of last month. This means we should get some answers soon.

Now that we have a number of 621s in use, is anyone able to comment on the benefits of video de-jittering?

TBH, what the HD621 does is probably more like HDMI signal re-conditioning, so that the HD621 can't be held "responsible" for downstream HDMI signal problems.

Personally, I don't think there's any such thing as jittered video, at least not in the sense that we understand it in audio.

Mark

I am merely taking up Meridian's terminology and claim.