HDMI cable advice

[Pete]

I was told yesterday by one of our engineers that he tried a cheap cable and it didn't work showing Blu Ray from his PS3, but worked for games!?

He was insinuating some form of protection within the cable itself. I tried to say that I didn't believe so - but not having played with any of this stuff didn't know what to think.

[mkirby]

i have quite an expensive set up and ive tried cheap cables and expensive cables and trust me its worth investing in decent quality cables, they say about 10% of your total systems value should be spent on cables!! i tried a cheapish one (that i use on my ps3) on my blu ray player and then swapped it to my normal hd cable and there is a difference, not a huge difference but there is!!

 

Mike

[Wez]

i have quite an expensive set up and ive tried cheap cables and expensive cables and trust me its worth investing in decent quality cables, they say about 10% of your total systems value should be spent on cables!! i tried a cheapish one (that i use on my ps3) on my blu ray player and then swapped it to my normal hd cable and there is a difference, not a huge difference but there is!!

 

Mike

 

For analogue signals I 100% agree.

 

For digital signals I dont see how you can gain anything, you are sending ones and zeros, they either get there or they dont.

[mkirby]

For analogue signals I 100% agree.

 

For digital signals I dont see how you can gain anything, you are sending ones and zeros, they either get there or they dont.

 

yeh but theres still a signal and a voltage carried so the better the quality the materials the better quality your going to get, dont get me wrong its not huge but when your talking about quite alot of monies worth of system its well worth it

[Wez]

yeh but theres still a signal and a voltage carried so the better the quality the materials the better quality your going to get, dont get me wrong its not huge but when your talking about quite alot of monies worth of system its well worth it

 

Again for analogue I agree just not for digital transmission.

[mkirby]

Again for analogue I agree just not for digital transmission.

 

well just going off what ive read and trying it for myself

 

Mike

[SatSport]

Wouldn`t go over £30 imo, you`ll get decent gold plated for that.

Real cheapies have inferior screening though and are prone to interference from other electrical stuff around the house.

[DaveK]

yeh but theres still a signal and a voltage carried so the better the quality the materials the better quality your going to get, dont get me wrong its not huge but when your talking about quite alot of monies worth of system its well worth it

 

That makes no sense. It's a "1" or a "0". How can it be a better quality "1" than I get with my cheap digital cable?

 

Analog makes logical sense - I changed to expensive interconnects recently and noticed a big difference. But for digital, I don't see how it can be anything other than placebo.

[Pete]

I guess there could be transmission losses as per any digital communication. How the error detection routines counter act this I've no idea, but could it be conceivable that the receiving equipment does some kind of best guess to repair data loss?

It would have to be really poor cable though. Think about SATA cables in your PC, they're cheap and passing masses of data.

[SimonB]

i have quite an expensive set up and ive tried cheap cables and expensive cables and trust me its worth investing in decent quality cables, they say about 10% of your total systems value should be spent on cables!! i tried a cheapish one (that i use on my ps3) on my blu ray player and then swapped it to my normal hd cable and there is a difference, not a huge difference but there is!!

 

Mike

 

There only difference is in your head, fact. It's like saying your digital photos on your PC will look better if you change the SATA cable connecting your hard disk up. There are a whole load of total rubbish tweaks in the hifi world that people seem to believe with absolutely no scientific basis. Things like your amp sounding better if you use special isolating rubber feet. Digital cables are a classic example of that.

 

It is true that some ultra cheapo cables struggle to pass full bandwidth 1080P 60fps because they are not HDMI1.3 compliant. However, you either get a perfect signal or it breaks up, there is nothing inbetween. I bought one like that, it would play blurays fine (at 1080P 24fps) but not PS3 full-on 1080P 60fps.

 

This place is where I buy mine from, the premium ones. A 3m cable is under a tenner.

[mkirby]

There only difference is in your head, fact. This place is where I buy mine from, the premium ones. A 3m cable is under a tenner.

 

well then you obviously are not that experienced in the world of home cinema etc, ive been into it for many many years and i have tried a couple if different hd cables on my setup and there is a difference, i'm talking from a cheapo one to a pretty decent one like but sorry bud but there is a difference, cant say ive noticed any difference on my pc though?? but i'm not that into pc's so i wouldnt know the ins and outs of the cables

[mkirby]

Wouldn`t go over £30 imo, you`ll get decent gold plated for that.

Real cheapies have inferior screening though and are prone to interference from other electrical stuff around the house.

 

i agree, you dont have to go mad, i paid i think about £40 for mine and there superb quality cables but nowadays as you say for £30 you can get just as good, i would just stay away from the sub £10 bracket

[JustGav]

I guess there could be transmission losses as per any digital communication. How the error detection routines counter act this I've no idea, but could it be conceivable that the receiving equipment does some kind of best guess to repair data loss?

It would have to be really poor cable though. Think about SATA cables in your PC, they're cheap and passing masses of data.

 

This is exactly it, while a cheap cable would work, digital errors and jitter would be introduced in an incorrectly shielded cable in a noisy environment. In most situations the cable/equipment would be able to correct/hide these errors.

 

There is a little bit of snakeoil in the hifi world, there is also a bit of scientific fact as well. A bad cable will not transmit a PURE signal over its entire length, perhaps in most cases the length is within digital correction tolerances.

 

I for one have noticed a cheapy cable cause artefacts however I did have a bundle of gigabit network cable near by.

 

If digital is just digital, would someone like to explain why gigabit networking can't just run over CAT3 over 1km? (standard telephone copper)

 

There is also the additional issue of digital reflection on a bad cable, as well as signal contamination.....

[SimonB]

well then you obviously are not that experienced in the world of home cinema etc, ive been into it for many many years and i have tried a couple if different hd cables on my setup and there is a difference, i'm talking from a cheapo one to a pretty decent one like but sorry bud but there is a difference, cant say ive noticed any difference on my pc though?? but i'm not that into pc's so i wouldnt know the ins and outs of the cables

 

Actually I have an extremely high end home cinema / hifi system. I was one of the very early adopters of DVD before you could actually buy discs in this country. I'm also a software engineer, so believe me I do know what I'm talking about!

 

HDMI does use error correction over the physical layer and the protocol layer. In order to be called a HDMI cable, it must meet the specifications, which ensure the error rate is such that it can be corrected by that error correction. It's the same with networking - you can use any CAT5 cable that meets the specs. You don't get "better" data if you use an expensive one!

 

Let's put it this way, I have yet to see ANY blind test that has resulted in anyone being able to see a difference between HDMI approved cables. Give it a go, get someone else to swap cables randomly so you can't tell which one is being used, repeat the test enough times to remove luck and I guarantee you won't be able to tell the difference.

[JustGav]

Actually I have an extremely high end home cinema / hifi system. I was one of the very early adopters of DVD before you could actually buy discs in this country. I'm also a software engineer, so believe me I do know what I'm talking about!

 

Fight, fight, fight

 

Just kidding, audiophiles are almost as bad as religious zealots, each one having a very strong view. I'm one of these odd ones that will have equal speaker cable lengths to ensure capacitance is the same not to affect tonal quality... (Does it make a difference, hell knows, probably not )

 

Also HDMI doesn't not feature digital correction at the cable level, there is no retransmission of a bad packet, it is essentially fire and forget, which means it is down to the equipment it fix/ignore the errors, too many then you would start seeing artefacts.

[mkirby]

Actually I have an extremely high end home cinema / hifi system. I was one of the very early adopters of DVD before you could actually buy discs in this country. I'm also a software engineer, so believe me I do know what I'm talking about!

 

Let's put it this way, I have yet to see ANY blind test that has resulted in anyone being able to see a difference between HDMI approved cables. Give it a go, get someone else to swap cables randomly so you can't tell which one is being used, repeat the test enough times to remove luck and I guarantee you won't be able to tell the difference.

 

So do i well i used to have a much bigger 7.1 system but in my new house the wife made me scale it down so i only have approx 10k system now, nothing i know to some ive seen but for a home its more than ok

 

I too started dvd when it was new, in fact i remember picking up one of the very first players i imported in, was a sony and cost me well over a grand and the shop didnt have a clue what it was LOL there used to be a great shop in the arndale in manchester who ised to import dvd's and had about the best selection around until trading standards shut them down for not having the correct age restriction logos on the discs!!

 

Oh and i never said you didnt know what your talking about and i have dont plenty of tests mainly to prove to friends and family that investing money in decent cabling is well worth it including hdmi cables and i did notice a difference and it wasnt just me maybe i just had a sh1te hdmi cable to start with??

 

All the best

Mike

[Dash Rendar]

I don't mean to be funny or owt but if you ask this over at AVforums you'll get a quick, concise answer and it won't degenerate into a fight.

 

Problem is, whenever I ask a question at AVforums, nobody ever bothers to reply. So now I just ask everything here!

[mkirby]

Problem is, whenever I ask a question at AVforums, nobody ever bothers to reply. So now I just ask everything here!

 

yeh they can be funny especially with newbies

[SimonB]

Also HDMI doesn't not feature digital correction at the cable level, there is no retransmission of a bad packet, it is essentially fire and forget, which means it is down to the equipment it fix/ignore the errors, too many then you would start seeing artefacts.

 

Error correction doesn't mean necessarily involve retransmission. That's only needed where the error rate is high. Yes, if you have a non HDMI compliant cable, or one that's not compliant to the spec you're using (i.e. 1.1 when you're using 1.3) or if you run it in a ridiculously high noise environment then you will get errors, but the encoding used means this would result in obvious picture errors (big sparkles all over the picture) or no signal at all because the clock would degrade. If your cable conforms to the HDMI spec you won't have a problem.

 

From 4.2.5 (physical layer) of the HDMI spec:

 

For each channel under all operating conditions specified in this section the following conditions shall be met. At TMDS clock frequencies less than or equal to 165MHz, the Sink shall recover data at a TMDS character error rate of 10-9 or better, when presented with any signal compliant to the eye diagram of Figure 4-20. At TMDS clock frequencies above 165MHz, the Sink shall recover data on each channel at a TMDS character error rate of 10-9 or better, when presented with any signal compliant to the eye diagram of Figure 4-20 after application of the Reference Cable Equalizer.

 

From 5.2.3 ("data" coding, basically everything that isn't video or a control signal -- audio, content protection, gamut metadata, etc.):

 

 

During the Data Island, each of the three TMDS channels ansmits a series of 10-bit characters encoded from a 4-bit input word, using TMDS Error Reduction Coding (TERC4). TERC4 significantly reduces the error rate on the link by choosing only 10-bit codes with high inherent error avoidance.

...

All data within a Data Island is contained within 32 clock Packets. Packets consist of a Packet Header, a Packet Body (consisting of four Subpackets), and associated error correction bits. Each Subpacket includes 56 bits of data and is protected by an additional 8 bits of BCH ECC parity bits.

...

To improve the reliability of the data and to improve the detection of bad data, Error Correction Code (ECC) parity is added to each packet. BCH(64,56) and BCH(32,24) are generated by the polynomial G(x) shown in Figure 5-5.

[SimonB]

... there used to be a great shop in the arndale in manchester who ised to import dvd's and had about the best selection around until trading standards shut them down for not having the correct age restriction logos on the discs!!

 

Funnily enough there used to be a shop round here that exactly the same thing happened to! That was when the only things you could get on DVD in region 2 were Contact and that crap film about a virus that I can't even remember the name of!

 

i did notice a difference and it wasnt just me maybe i just had a sh1te hdmi cable to start with??

 

Can I ask what area you though was better about it? Were you getting picture breakup with the other cable?

[Thorin]

Did nobody see the episode of the Gadget Show where they tested the cheapest cable they could find, against one costing over £100?

 

...or perhaps the post I made earlier where I quoted the very in depth tests made by some AV geeks? Let me quote the relevant bit again...

 

At lengths less than 4 meters you can just about use silly string (OK, not really) and get HDMI to pass at any current resolution.

 

Unless you're using very long cables, there's no difference in using expensive cables.

[GazzaGSi]

I agree.

For my PS3 I was using a HDMI cable from... thecableman on ebay. Cost me about a fiver delivered if that.

Mate at work lent me his £30 cable from currys and there is absolutely no difference at all.

 

Something completely irrelavant, I did notice the difference with a decent scart lead compared to my £1 jobby lead with Sky+.

[jamesmark]

Finally went for a £2.99 (+ £2 P&P) cable 1.5m off ebay.

[DaveK]

I don't mean to be funny or owt but if you ask this over at AVforums you'll get a quick, concise answer and it won't degenerate into a fight.

 

Funnily enough - the exact same subject is being discussed there right now and it has degenerated into a fight!

[Pete]

Got my PS3 yesterday and today got a cheap HDMI cable from work (about a fiver) and an DVI to HDMI convertor, chucked it all together and it played The Dark Night wonderfully!