HDMI Scam

[jvc]

Some people are very susceptible to suggestion. They are told they will hear a big difference with expensive cables, so they do. They will swear they do, and almost be ready to fight you, if you tell them they aren't really hearing a difference. Especially if they bought expensive cables already. They will say or do anything, to justify the money they spent.

I knew a guy back in the 60s that you could give him a sugar pill, tell him a drop of LSD was put on it, and he would trip his brains out for a couple of hours. He was very susceptible to suggestion.............

 

[TheForce]

Tony-

Isn't a double blind test one in which nobody knows what the test is that is being performed? Been quite awhile since I worked on this stuff and things may have changed but when we did double blind, the respondents were asked to select from a set of samples and they had no idea what the test was for. Consequently, if you say I will have you select whether you can hear the difference in this cable or that cable it already would violate the double blind, right? If you didn't know which cable was the $5 or the $100 that would only be a single blind test.

However, if I set up a test and asked 5 volunteers to to pick whether A sounds like B(better than), C(worse than) or D ( no difference) and we do this for 20 trials, ( 100 data points) we could then determine the validity under double blind parameters whether or not the $ 5 cable is worse than, better than or same as the $100 cable. It is double blind because neither the respondents NOR the testors know what is a $5 cable or a $100 cable. Only I would know and I am not administering the test. I only will tabulate the data from the test results.

 

[jayn_j]

Tony-

Isn't a double blind test one in which nobody knows what the test is that is being performed? Been quite awhile since I worked on this stuff and things may have changed but when we did double blind, the respondents were asked to select from a set of samples and they had no idea what the test was for. Consequently, if you say I will have you select whether you can hear the difference in this cable or that cable it already would violate the double blind, right? If you didn't know which cable was the $5 or the $100 that would only be a single blind test.

However, if I set up a test and asked 5 volunteers to to pick whether A sounds like B(better than), C(worse than) or D ( no difference) and we do this for 20 trials, ( 100 data points) we could then determine the validity under double blind parameters whether or not the $ 5 cable is worse than, better than or same as the $100 cable. It is double blind because neither the respondents NOR the testors know what is a $5 cable or a $100 cable. Only I would know and I am not administering the test. I only will tabulate the data from the test results.

Strictly true. The problem in this case is that there is a physical visual difference among the cables. In order for it to work, you need one more level of indirection. You could add switching, but that will also add a variable into the signal path. People could argue that the switch itself takes away upper badwidth, or some inherent characteristic of the signal.

A cleaner way is to have someone out of the room connecting cables. The test administrator selects a number and the person behind the curtain connects the cable associated with the number chosen. That would be a true double blind.

I would also suggest separating the audio from the video test as one can influence the other. Always best to test just one thing at a time.

 

[Ben Bassinger]

If HDMI was all or nothing, when running long runs, you would only have to worry about getting or not getting the signal. You would never see the green/blue sparkels in the picture nor have audio/video drop outs. Therefore over short runs, it is possible to not get all the bits of information in which it would cause signal loss. That's all I'm saying. In the test I did, I did not know which cable was which. They were swapped out and I was asked if I could hear a difference. If you've got the good equipment, why not make sure you get the good signal. I can see artifacts in the picture at close distances with test patterns between cables. I don't think ANYONE could see those at normal viewing distances and programming(I can't) unless obvious pixel loss with long runs. However, I can HEAR differences, so I will continue to support my equipment with the best cables I can for Audio. Some people can't hear the diffenence in DTS/DD and Lossless HD audio, if you can't, don't waist your money. I also know people who can hear the difference between Dolby Digital 5.1 and DTS 5.1, so make a decision based on what YOU hear or see, don't listen to anyone else. It's like someone asking what speakers sound better. Each speaker sounds different to each person's ears. Don't do something because I said so or anyone else for that matter. Try it out. Go to Best Buy, buy some nice Audioquest or "gasp!" Monster and try it, if you hear a difference, return them and find them cheaper if you want, or if you don't hear any difference, return them and be happy knowing you got what sounds good to you. I'm just sick of the "It's digital, it's all or nothing" argument.

 

[Ilya]

However, I can HEAR differences, so I will continue to support my equipment with the best cables I can for Audio.

Ben, just curious, which cables/brands (and what length) did you compare in that blind test and can you describe what the difference was? As I understand, HDMI errors can manifest as clicks and pops and also as sound quality degradation. So, what exactly did you observe?

 

[Ben Bassinger]

Ben, just curious, which cables/brands (and what length) did you compare in that blind test and can you describe what the difference was? As I understand, HDMI errors can manifest as clicks and pops and also as sound quality degradation. So, what exactly did you observe?

I'm not out to recommend or disparage any companies or pitch you guys products so I'll leave the brands out. I will tell you I have used cables from just about everyone/everywhere. What I observed over standard 4ft cables was an "openess" to the sound. From what I could here the higher frequencies were clearer and more precise. I was listening to a famous piano player/singer(Really can't remember who). His voice was more natural and localized not boomy. The piano keys and strings resonated clearly with the good cables versus a "ringing" with cheaper ones. It almost seemed like the sound was attenuated and "cut off" with the cheap cables. I never observed any pops or clicks, but the soundstage was clearer to point out. The only time I get pops or clicks is with cheap/damaged cables at longer lengths ~12-30+ft. The reason I say damaged, is I've used cables that had issues, then swapped them with the exact same cable brand and type and the issues go away. I enjoy the sound with the better cables, so I replaced mine. Some devices(cd,hddvd,bluray,phono"j/k") I can here a major difference. With regular dvd, it was not as prononced which is funny because I thought dvds had better bitrate than cds, but I guess not. If you try it, don't hear anything, take em back. No harm, no foul but you might just be suprised.

 

[TNGTony]

Double blind, neither the person asking the question nor the person answering the question know what A or B are. There is a third person physically changing the cable (or not to throw off the test subject) the cables and telling the tester to ask the question.

So some one would hook up the cable and tell the tester, to administer the test. The respondent takes the test. The third person disconnects the cable and reconnects A cable (could be the same one, could be a different one) and then tells the tester to administer the test.

This works great. Doing this I have earned some cash from people who insist they can tell the difference between 18 gage lamp cord and some overpriced audio cable back in the day. I have also done this once with two people (in the same test so they actually could collaborate) who insisted they could see the difference between HDMI and Component 6 foot run on a 42" 1080i Plasma TV.

I haven't done it with cheap vs expensive HDMI but I would love to do so.

 

[Ilya]

What I observed over standard 4ft cables was an "openess" to the sound. From what I could here the higher frequencies were clearer and more precise. I was listening to a famous piano player/singer(Really can't remember who). His voice was more natural and localized not boomy. The piano keys and strings resonated clearly with the good cables versus a "ringing" with cheaper ones. It almost seemed like the sound was attenuated and "cut off" with the cheap cables.

Interesting... I do understand how jitter, bit errors and interpolation can cause some of the described effects. But for such a noticeable difference in sound quality the bit error rate had to be extremely high! And at just 4ft??! That's strange! The cheap HDMI cables must have been really bad!
Not questioning your observations, just trying to understand them.

 

[diogen]

It is hard to prove a negative.
Doesn't mean it is easy to prove the positive.

Here is an interesting discussion about jitter and whether it is audible.

Audible Jitter/amirm vs Ethan Winer
Here for example (from page 3 of that discussion) is a schematic of cable induced jutter

and here are some numbers what HDMI does to the sound on above average AVRs

"In the Feb 2009 edition of the Hi-fi News magazine Paul Miller measured the following jitter results for a few A/V amplifiers:

Denon AVR-3803A
---------------
SPDIF: 560psec
HDMI: 3700psec

Onkyo TX-NR906
---------------
SPDIF: 470psec
HDMI: 3860psec

Pioneer SC-LX81
---------------
SPDIF: 37psec
HDMI: 50psec

Yamaha RX-V3900
---------------
SPDIF: 183psec
HDMI: 7660psec"

The bottom line the way I understand it: It is there and easily measurable.
And if you spend $100K on your equipment, bass traps and room treatment, listen to music on $1500+ headphones,
take some lessons what you actually should listen to, etc. you have a chance to hear jitter.

Diogen.

 

[Ben Bassinger]

The bottom line the way I understand it: It is there and easily measurable.
And if you spend $100K on your equipment, bass traps and room treatment, listen to music on $1500+ headphones,
take some lessons what you actually should listen to, etc. you have a chance to hear jitter.

Diogen.

The science/engineering of it all goes way over my head, but I can see how it could make a difference. I don't have 100k of equipment(would like to) or $1500 headphones. I do have pretty decent ears(might be a little big) and I like what they hear.

Bottom Line: If you like what you have and enjoy it, stick with it, sit back and listen. This is an awesome hobby that brings great joy to people. Throw on some music or movies and don't worry about the billions of electrons that make it all work!

 

[raoul5788]

Bottom Line: If you like what you have and enjoy it, stick with it, sit back and listen. This is an awesome hobby that brings great joy to people. Throw on some music or movies and don't worry about the billions of electrons that make it all work!

This IS the bottom line. If you have something you enjoy, enjoy it, don't over analyze it. I wish my last girlfriend understood this concept!

 

[DodgerKing]

It is hard to prove a negative.
Doesn't mean it is easy to prove the positive.

Here is an interesting discussion about jitter and whether it is audible.

Audible Jitter/amirm vs Ethan Winer
Here for example (from page 3 of that discussion) is a schematic of cable induced jutter

and here are some numbers what HDMI does to the sound on above average AVRs


The bottom line the way I understand it: It is there and easily measurable.
And if you spend $100K on your equipment, bass traps and room treatment, listen to music on $1500+ headphones,
take some lessons what you actually should listen to, etc. you have a chance to hear jitter.

Diogen.

So IOW, if you have the same equipment that most on here have, and have the hearing of that of most people, you will not be able to hear any difference at all? IOW, don't waste money on expensive cables unless you are foolish enough to spend triple digits on audio equipment. Even then, most wont be able to hear a difference between a $2 cable from monoprice and a $120 Monster cable

 

[DodgerKing]

Well, if so, then you are missing out on all the advancements in sound quality that were introduced with Blu-ray. The home theater sound quality has improved dramatically from DVD to Blu-ray. The new lossless audio formats like Dolby TrueHD and DTS-HD Master Audio leave Dolby Digital in the dust.

And there are two ways you can take advantage of these new Blu-ray audio formats: either upgrade your receiver to a the one that can handle HDMI, or get a Blu-ray player with 5.1 analog audio outputs (if they still make those). That will make a huge improvement even with your existing AV receiver, provided it has 5.1 or 6.1 analog inputs.

I believe my analog inputs cannot do DTS or DD 5.1. I think they do stereo only. Only my digital inputs are capable of that.

I have a silver Yamaha HRT-5650. It does have a 6ch analog input, but my PS3 does not have a 6ch analogy output. The only way I can get DD 5.1 and DTS 5.1 from my BR player to my audio receiver is via optical. Is this correct?

 

[diogen]

So IOW, if you have the same equipment that most on here have, and have the hearing of that of most people, you will not be able to hear any difference at all? IOW, don't waste money on expensive cables unless you are foolish enough to spend triple digits on audio equipment. Even then, most wont be able to hear a difference between a $2 cable from monoprice and a $120 Monster cable

That is my understanding, yes...
But there is no - and can't be - objective proof that jitter is inaudible.
Even if only because it can be heard under circumstances described above.

And I believe the main bottleneck is not the equipment cost but limitations of human hearing...

Diogen.

 

[diogen]

The only way I can get DD 5.1 and DTS 5.1 from my BR player to my audio receiver is via optical. Is this correct?

The BD player being the PS3? Correct.

The cheapest way to get access to the better soundtracks is to replace your AVR with one having HDMI and capable of decoding lossless BD soundtracks.
Those AVRs start around $250 today.

Unless you want to hear jitter, that is...

Diogen.

 

[jayn_j]

The BD player being the PS3? Correct.

The cheapest way to get access to the better soundtracks is to replace your AVR with one having HDMI and capable of decoding lossless BD soundtracks.
Those AVRs start around $250 today.

Unless you want to hear jitter, that is...

Diogen.

The problem I have here, is that the jitter you are describing is real, but this is a digital signal. It is only going to be an issue if the amount of jitter delay is long enough to exceed the sample rate. That would cause aliasing problems, and that would be fairly obvious. Macroblocking in the video and pops in the audio.

What you are describing applies to an FM modulated ANALOG signal. This is what laserdiscs used, and there you could see video jitter and mayby hear some audio flutter.

That isn't going to happen with digital signals because the signal is either above the threshold at the sampling point or it isn't.

 

[diogen]

I said this before: I don't hear jitter for many reasons and don't regret it a bit...

But I find the discussion I linked to above very convincing. As well as the papers it is linking to.

I don't think it is an analog signal.

There are many ways to screw up the audio stream.
Jitter comes into play when everything else is perfect...

Diogen.

 

[mike123abc]

Jitter may exist but it is not going to be caused by the HDMI cable. The HDMI signal as mentioned above has error correction and encryption. The only way to perform this error correction and decription is to buffer blocks/packets of data into an internal memory buffer of the receiver. Once a block of data has been received the error correction is done then decryption is done. If the errors in the transmission exceed the error correction then you lose the block.

Once the decryption is done it is clocked out of the memory buffer using a clock on the receiver for the D to A conversion in the case of sound. It is possible for the clock on the receiver to induce jitter. But, it was not caused by the HDMI cable or anything before the error correction/decryption buffer.

All these cable myths come from the old analog stereo world. Why do we expect 10GBit-TX ethernet over Cat 6A cable to reliably deliver every bit of information over 100meters and cannot expect a short run of cable to deliver a 2Gbit/sec (assuming standard 1080p) signal?

 

[jayn_j]

I said this before: I don't hear jitter for many reasons and don't regret it a bit...

But I find the discussion I linked to above very convincing. As well as the papers it is linking to.

I don't think it is an analog signal.

There are many ways to screw up the audio stream.
Jitter comes into play when everything else is perfect...

Diogen.

I will read the referenced papers in more detail, but I am VERY skeptical. This is a field where I have 30 years of engineering experience. There is a lot of pseudo-scientific jabber out there in audio land where someone starts with a conclusion and then tries to find a theory that fits. Not saying this is the case here, as I haven't read the papers in sufficient detail, but the mere existance of the papers is not sufficient proof for me. Stay tuned.

 

[diogen]

I'm not qualified to discuss this from the scientific side.
But from what I read, the science is sound (no pun intended ), and I do know what BS science is...

My understanding:
Jitter means clock issues. The clock data is NOT transfered.
(There was an article referenced some years ago on AVS about how Meridian tackles this...)
The signal (zip) arrives bit perfect and is unzipped bit perfect (no decryption issues).
DA conversion with the player's clock introduces jitter.

As a side note: the zip analogy isn't quite right here.
Audio/video playback is a time sensitive stream while zip/unzip applies to a file outside the time domain.

Diogen.