It is a commonly held belief that spending a lot on digital cables is a waste of money. Unlike analogue, where it makes a difference, though not as much a some Hi Fi manufacturers might suggest, digital cables carry ones and zeros so there is there anything to be gained from ‘high end’ digital cables?

In a recent podcast, embedded below, I was questioning the cost of laptop docks. I was surprised by how much a quality dock with the complement of connections I was looking for cost. Thunderbolt ports in particular drive the cost up significantly. There are certification requirements associated with adding Thunderbolt ports which impact the costs. But while manufacturers are of course running businesses and seek to make a profit, actually in that case I wasn’t giving enough attention to the fact that the extreme performance of a high speed connection like Thunderbolt isn’t easy to pull off and some really clever engineering is involved. And precision engineering costs money.

A Cable And Some Connectors

When it comes to cables

It’s easy to assume that two cables with the same connectors on each end are the same. A nice XLR cable with Neutrik connectors and Van Damme cable is functionally identical to a cheap, no-name XLR. The cheap one will probably break sooner and won’t handle as well but the both do the same job. The same can’t be said of cables with USB-C connectors at each end. A quick search for 2m USB-C cables on Amazon reveals an unbranded charging cable at £3.79 and at the other end of the scale a Thunderbolt 4 cable at £162! While these cables might physically fit the same sockets, that’s where the similarity ends.

So are Thunderbolt cables overpriced? Can such a huge difference in price be justified? The video below from Adam Savage’s Tested, addresses exactly this question by comparing a $130 Apple Thunderbolt cable with a $13 Amazon USB cable and a couple of really cheap no-name cables from Amazon by inspecting them with CT (computerised tomography) scanning and visualisation technology from Lumafield. This allows a 3D X ray visualisation to be captured, meaning that it’s possible to examine complex assemblies without having to disassemble them, something which wouldn’t be easy and definitely wouldn’t be reversible with products like these.

A Look Inside A Thunderbolt Cable

The results are fascinating and offer a window into the complexity, design and execution of something we usually take for granted apart from when we are raising our eyebrows at the cost!

Among many other points, here are some of the points of interest in this video:

• Thunderbolt offers direct connection to the PCI Bus, one of the engineering challenges Thunderbolt seeks to fix is managing this over long distances outside a computer. We’re probably all aware that there is some clever technology built into Thunderbolt cables, including a chip, but there is a lot more hardware built into a Thunderbolt cable than you probably realise.

• There are processors built into cables complete with power supplies. The visualisation reveals nine layers in the PCB. This hardware controls data management, sending audio in parallel, multiplexing it and demultiplexing at the other end. Even the traces on the PCB are physically time aligned. The traces have ‘wiggles’, to add length to make the traces exactly the same length to ensure parallel signals arrive simultaneously.

• The signals in the cable itself are very small, with tiny voltages. The cable uses a very complicated, and beautifully executed, assembly of 20 cores. The cores are co-axial and in twisted pairs. They use a similar system to the familiar line balancing we find in audio cables to protect these signals from interference. There is a very precise twist applied to all of these cores with strain relief and grounding. This contrasts sharply with the construction of the other cables!

Are Cheap Cables ‘Bad’ Cables?

In this examination, the cheap cables are revealed to be everywhere from imprecisely to shoddily constructed. Are the people making these cables cowboys selling products which are unfit for purpose? Actually not at all. Charging is the most popular use for USB C cables. Using a $130 cable just to charge a device is over the top. The manufacturing tradeoffs are, for the most part, perfectly justifiable. You get what you pay for. But manufacturing quality is still important as damaged charging cables put hardware devices at risk.

Does this matter? Only in as much as it isn’t clear when you buy a cable what you are buying. Many consumers buy a cable that fits, usually not considering the differences and unfortunately the functional difference between a cheap charging cable and an expensive Thunderbolt cable isn’t always easy to discern, other than by the price...

Watch the video and you’ll see just what you are paying for.