Tearing down a $3.29 HDMI cable – what’s inside

HDMI-1Sometime ago, I made the point that I thought that HDMI cables are overpriced and that, in essence, you shouldn’t need to spend more than $10 per metre for a decent cable provided all 19 pins on the HDMI plugs were wired up and that it had at least AWG28 gauge wire inside. Later, a reader suggested spending $50 to $100 for a cable should be the norm.

If you take a look online at eBay, you’ll find dozens of ads for super-cheap HDMI cables. How cheap? Try $1 for a two-metre cable. Now frankly, while I’m averse to spending $50 for a basic 1.5-metre HDMI cable, even I’m a bit sceptical of just how good a $1 HDMI cable can be. Nevertheless, could they be as bad as some people say? So I decided to find out and purchased a two-metre HDMI v1.3b cable from eBay, spending a grand total of $3.29, and that included shipping. (As you can see, I spared no expense!)

What’s that smell?

Ten days later, the cable arrived in a small padded bag but upon opening it, the chemical odour was hard to ignore. Not to put to fine a point on it, it reeked.

The cable itself had what appeared to be decently-made HDMI connectors on both ends with end caps while the cable itself was encased in a plastic mesh sheath. The other thing was that the cable itself was quite stiff and not all that pliable. It didn’t look the most robust of cables but we didn’t plan on flinging it around like a whip, it just needed to work.

Comparison

We tested the cable between a Panasonic LCD TV and Sony BDP-S350 Blu-ray player with both devices set to use 1080p transfer, replacing the original two-metre cable, which we purchased for around $50 about three years ago. That original cable was a true 19-pin cable that allowed the Panasonic remote to turn off the TV and the Blu-ray player at the same time, through the HDMI cable using what’s called Consumer Electronics Control (CEC), a single-wire communications protocol built into the HDMI specification.

HDMI-2Now to the test – with a 1080p Blu-ray disc, we found nothing wrong with the image quality. The TV and the Blu-ray player happily negotiated the 1080p handshaking and we had full 1080p (1920×1080-pixel) high-definition video and multi-channel sound coming through to the TV. No noticeable image problems, no breakups, no dropouts, no failures.

Since the cable was sold only as a v1.3 cable, we didn’t test it with Blu-ray 3D, where a v1.4 cable is needed.

However, our first hint that not everything was kosher was when the TV remote no longer turned off the Blu-ray player. That means CEC is not implemented and given CEC wiring is considered mandatory in HDMI cabling, it’s one area where this cable doesn’t meet requirements.

Inside the cable

HDMI-3

Having established that the cable worked as far as video/audio transfer was concerned, we decided to pull it apart and see how it was constructed.

Inside, we found only 13 wires rather than the 19 expected, surrounded by multiple layers aluminium foil shielding.
In practice, two metres isn’t a long cable run and short enough to get away without having those four shielding pins. While we’d be less confident of this cable type over runs of more than three metres, as a budget short-length cable, it worked. Now the reason the cable still works is the HDMI standard has six pins that are not strictly necessary – four of those wires are shielding for TMDS Data 0, TMDS Data 1, TMDS Data 2 and TMDS Data Clock. The fifth pin/wire is designated as simply a “Reserved” pin in HDMI cable standard up to v1.3c and is used as an optional Ethernet connection in v1.4 cables. The TMDS (Transition Minimising Differential Signalling) pins already use a noise-reduction technique to reduce interference. The shielding pins provide further protection from RF (radio frequency) interference over longer runs but are not actual data pins.

The sixth wire missing was the CEC, something we didn’t expect, especially given it’s a mandatory requirement of the HDMI spec. That said, it isn’t strictly necessary for video/audio transmission so this particular manufacturer decided if it wasn’t needed, it was another wire that could be removed, reducing cost.

Are all cheap cables good enough?

We’re not saying that every cheap HDMI cable will be perfect. That would be clearly silly. We may have got lucky with our $3.29 cable, we might not have. However, one thing is for certain – after this experience, I’m even less inclined to spend $100 per metre on HDMI cables. But I might just spend a little more than $3.29.

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