HDMI Cable Scams

As part of the ongoing setup of my new work laptop, I had to get an HDMI cable to connect my laptop to my monitor. We ended up with a reasonably low-cost one from an online vendor. When it arrived, I was surprised to see the cable’s packaging claim that the cable “drastically reduces signal distortion” by using silver-plated, oxygen-free solid-copper conductors.

Right, see, that’s a load of crap. Let’s start with the fact that HDMI signals are digital. The signal is a series of voltage changes indicating ones and zeros. What does it mean to “reduce signal distortion”? That cheap cables send 0.8s instead of 1s? And oxygen-free copper? Yes, oxygen turns copper green and flaky, but cables don’t oxidize, especially now that they’re wrapped in a snuggly blanket of foam polyethylene dielectrics. Using oxygen-free copper over regular copper buys you nothing. Or as a friend of mine sarcastically said, “Yeah, the 1’s in binary are scientifically proven to prefer copper with extra oxygen.”

Expensive audio cables are notoriously burdened with mystical woo-woo explanations of how they prevent analog signal distortion, when the truth is that you’d do just as well with lamp cord. Now that hand-wavy approach has apparently spread to video cables, and done so in the digital realm, where the vague tissue of plausibility regarding distortion doesn’t apply.

It gets worse when you realize how much mark up stores add to cable prices. We saw this back when Misty worked for Apple while based in a CompUSA. CompUSA gave her access to employee discounts. We could buy most things from them for some 5% over cost. Looking at the store’s cost for cables versus what they were charging the public was eye-opening.

You need HDMI or DVI cables? Go to some place like Monoprice. They’ll sell you six feet of HDMI cable for under $13. Heck, even Apple (!) will sell you a six foot HDMI cable for $20. For comparison, Best Buy will happily sell you a six foot HDMI cable for $60. If you’re really looking to be fleeced, they’ll sell you a 4 foot Monster cable for $80.

I know which one I’d go for.

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7 Comments

  1. on January 14, 2008 at 10:43 pm | Permalink

    You know, I completely agree that boutique cables are one of the biggest scams out there. If you ever want to see the core of the crowd that buys into this, pick up a back issue from the 90’s of a magazine called Stereophile… preferably one of the ones that has the “recommended components” section. The thing is, there’s good info in there, but then there’s also the scary buy-in and the ads. *shudder*

    That being said…

    Let’s start with the fact that HDMI signals are digital. The signal is a series of voltage changes indicating ones and zeros. What does it mean to “reduce signal distortion”? That cheap cables send 0.8s instead of 1s?

    I know you know better than this. 🙂

    Everything is analog. Especially high speed digital signals. Ask Rick what can happen to a memory signal as it travels 1-inch down a PCB trace. Prepare for the rant.

    Basically, not all of that “1” gets there at the same time. Then, if there’s an impedance mismatch, some of it bounces back down the cable, then back up the cable. Suddenly, a “1” might look like a “0” or vice versa. You should see what nasty stuff multiple reflections can do to a pretty digital pulse.

    It gets other names in the digital world, but it’s caused by the same electrical characteristics of the cable that create what we call “distortion” in an analog signal.

    So… I’d probably be scared of a $2 HDMI cable. $13 in comparison to the ripoff price Monster wants sounds about right, though.

  2. on January 14, 2008 at 11:21 pm | Permalink

    It gets other names in the digital world, but it’s caused by the same electrical characteristics of the cable that create what we call “distortion” in an analog signal.

    But impedance mismatch and the like are expressly not what the cable packaging is claiming to fix. And signal issues in a digital setup like HDMI is going to show up as the picture going batshit crazy, not as it being not quite as sharp as it otherwise might be. Everything might be analog at its heart, but digital failure modes aren’t like analog ones.

    HDMI cables have to pass the test specification to get the HDMI logo. Given how much money the HDMI licensing corporation rakes in, you can bet they’ve got their jackboots ready to stomp on anyone who uses that logo on or claims certification for bum cables.

  3. on January 15, 2008 at 12:46 am | Permalink

    Sure. I completely agree with your basic premise that boutique cable vendors make meaningless or utterly false claims in order to sell us snake oil. I just had to pick on you a bit for the “0.8s” comment. 🙂

    You make a very good point that the artifacts created by digital signal problems are in general very different from those created by analog signal problems. Anyone who has digital satellite TV can attest to the fact that when the signal gets bad, the resulting picture problems look very different than when an analog cable or over-the-air TV signal gets bad.

    The funny thing? I’ve seen the snake oil vendors play the other side of this coin as well. I have to shake my head and sigh every time I see a company claim that their product or service has “digital quality”. 🙂

  4. on January 15, 2008 at 3:56 pm | Permalink

    Stephen came back with pretty much exactly what I was going to say. If they’re going to sell it as HDMI, it had better meet the specifications and that should include quite a bit of margin to avoid any sort of signal integrity problems.

    Assuming the margins are solid enough, I could get behind a cable that sent 0.8’s instead of 1’s (assuming that’s a scale of the DC voltge). That just means it uses less power and is more ‘green’. That ought to make it worth at least a few dollars more. 😉

    The real error in the digital world comes from quantization (initial conversion from analog to digital). This happens on the recording side rather than the playback side, so I guess they can’t soak the consumer on that.

  5. on January 15, 2008 at 5:04 pm | Permalink

    Can I just say that it’s fun to watch my friends out-nerd each other? 😉

  6. on January 15, 2008 at 9:18 pm | Permalink

    Rick, I dunno, I think Jeff’s claiming digital systems can transmit the equivalent of 0.8s.

  7. Mack
    on January 24, 2008 at 10:00 pm | Permalink

    Yes, the fluff and lies from cable vendors is junk, but it is not correct to say its just 1’s and 0’s down the line. DVI/HDMI is a digital transport system, but when its over copper, its an analog world.

    What no one ever points out is that the chipsets in the TVs should be using proper signal recovery techniques to basically undo all the impairments that occur after those 1’s and 0’s are sent down the line. There is inter-symbol interference, reflections, jitter, skew, and differences in loss between individual conductors. Using simple chip design techniques (i.e. most chip vendors in this market do) causes a vast majority of the problems users complain about.

    Find a TV or Projector with advanced silicon (lookup Vividreach) and you experience everything you ever thought HDMI should be. Saw it at CES and it was unbelievable. PS3 sending 1080p/60Hz/Deep Color over 20+ meters of thin 28AWG HDMI Type I cable with instant signal lock. Even better was the same signal working flawlessly over 100ft of Cat5 without any boosters, electronics, repeaters, etc.