Maximum length for hdmi lead

[c12038]

whats the maximum length to connect TV to GFX hdmi socket (PC one end of room approx. 20-30 ft away from TV) any ideas guys

[kalniel]

whats the maximum length to connect TV to GFX hdmi socket (PC one end of room approx. 20-30 ft away from TV) any ideas guys

There isn't one. If you've got a good enough cable and signal then could be any length.

[Saracen]

There is no maximum length, as such. The issue is the level of signal loss (attenuation).

The simple way to view is it that attenuation depends mainly on :-

- cable length
- frequency of the signal
- quality of materials and construction.

You will find two levels of cable, Category One and Two, usually labelled Standard and High Speed, respectively. This refers to the frequency at which they've been tested. The higher the resolution of the display your driving, or rather, of the signal you're sending, the bigger the attenuation will be as cable length increases. So, the effect of attenuation will be worse as cable length increases, but a given cable for 720p might be adequate, but won't at 1080p.

Assuming you want true HD, and at a length of 25', I'd suggsst that Category 2 (High Speed) is worth looking for BUT it's likely to be significantly more expensive. On the other hand, a "stansard" 25' cable might well work .... if you can find one.

Bear this in mind. These "categories" mean a cable has been tested at a given frequency. Just because a category 1 cable hadn't been tested at high frequency doesn't mean it won't work, just that it hasn't been tested.

So, a category 1 cable MIGHT do what you want, or might not. A category 2 cable should be fine at, say 15m, for HD. You pays your money, and takes your chance. Or not.

And, by the way, for short distances, I'm far from convinced it matters at all.

[MrRockliffe]

Well HDMI is digital, so in theory it doesn't matter. However, it would be better to get a high speed cable. Amazon's cables are really high quality - I've used them for a year now and really like them.

[c12038]

cheers guys for the info might look now for a Cat 2 hdmi cable

[Saracen]

Well HDMI is digital, so in theory it doesn't matter. However, it would be better to get a high speed cable. Amazon's cables are really high quality - I've used them for a year now and really like them.

Sorry, but in theory it absolutely does matter.

Impedance increases with the rate of frequency change in the signal state. What you need, for example, for a cable carrying an HF radio signal is FAR less demanding than a UHF signal, and when you get to microwave frequencies, cable quality, and connector quality, are major issues.

Even digital signals involve frequency changes. At a basic level, it's on or off. The effect of impedance if you change that 100 times a second are far less than if you change it a million times a second. There are differences in the way it impacts, not least because digital methods can build in redundancy, increasing efficiency in how you compress and encode, and checkinf/resending, in a way that analog can't, so the effect on the reconstructed signal vary, with some dramatic impact on audio or video quality being noticeable.

But that's not the point here. The point is the way cable length and the rate of change of signal state react with impedance, which varies with the quality of the material in the cable, the number and quality of connectors, and the length of the cable run.

[peterb]

I'll just add that I have come across equipment that won't work reliably if the cable is too short - I have never investigated fully, but I suspect it is because of multiple reflections along the cable, either because the HDMI receiver is poorly designed of oversensitive.

[jimborae]

Had issues with cables over 15m in length before, signal and hdcp handshake loss, sparklies etc. having said that it was a cheapo cable and non boosted signal

[TheDutyPaid]

This is quoted from http://www.hdmi.org/learningcenter/faq.aspx#top

"Q. Does HDMI accommodate long cable lengths?

Yes. HDMI technology has been designed to use standard copper cable construction at long lengths. In order to allow cable manufacturers to improve their products through the use of new technologies, HDMI specifies the required performance of a cable but does not specify a maximum cable length. We have seen cables pass "Standard Cable" HDMI compliance testing at lengths of up to a maximum of 10 meters without the use of a repeater. It is not only the cable that factors into how long a cable can successfully carry an HDMI signal, the receiver chip inside the TV or projector also plays a major factor. Receiver chips that include a feature called "cable equalization" are able to compensate for weaker signals thereby extending the potential length of any cable that is used with that device.

With any long run of an HDMI cable, quality manufactured cables can play a significant role in successfully running HDMI over such longer distances."

"Q. How do I run HDMI cables longer than 10 meters?

There are many HDMI Adopters working on HDMI solutions that extend a cable’s effective distance from the typical 10 meter range to much longer lengths. These companies manufacture a variety of solutions that include active cables (active electronics built into cables that boost and extend the cable’s signal), repeaters, amplifiers as well as CAT5/6 and fiber solutions."

[Barakka]

cheers guys for the info might look now for a Cat 2 hdmi cable

With where you are based check out CPC - just off J31A of the M6 (Preston), they have everything and since they stopped being trade only their sales counter is now open 7 days...

They have 35 different 10M HDMI leads in stock and the prices are usually very good (High Speed ones from £9) as they supply a lot of the high street shops.

[g8ina]

I have a 20m HDMI going spare if you want it for post ?

[c12038]

I have a 20m HDMI going spare if you want it for post ?

Thanks just need to some homework no on this will keep it in mind