Everything you need to know about HDMI cables, from quality and construction to versions and features.


HDMI, or High Definition Multimedia Interface, is the current standard for high definition video. Capable of carrying high definition video, surround sound audio, EDID handshaking signals, Ethernet and IR signals via a single cable, HDMI has solidified its standing as the industry standard for easy and efficient high definition video runs.

Available from Sewell Direct - The very latest in HDMI technology

HDMI 1.4 high speed with ethernet

Both our Standard and Premium lines of HDMI Cables feature the latest upgrades to HDMI technology. HDMI High Speed with Ethernet cables are the top of the line HDMI cables on the market today, offering compatability for your newest device's full set of features, including: 3D support, ethernet channel, audio return, and a 4K resolution to ensure your cable doesn't go obsolete for a long time.

Why is HDMI better?

Older signal formats like RCA, VGA, or DVI all suffer from technical or convenience issues that leave HDMI the clearly superior format. The maximum resolution for RCA is 480i, while HDMI can carry a full 1080p signal. DVI can carry 1080p as well, but it doesn’t include an audio channel. You are forced to run either an extra 3.5mm audio cable for simple stereo sound or a fragile SPDIF cable for surround sound.

HDMI combines and surpasses the specs from multiple previous video formats, capable of carrying full 3D 1080p signal and 7.1 Dolby digital surround sound in a single sturdy cable. It also has an EDID handshaking channel which means that source devices are able to interface with display devices in a way that analog signal formats can’t. This allows your source device to custom tailor its signal content for the receiving device, cutting down on incompatibilities and facilitating ease of use.

How do I use HDMI?

Like most video formats HDMI is as simple as plugging it in and letting it run! All you’ll need is an HDMI source device and a display with an available HDMI port. Just plug one into the other with a single HDMI cable and watch high definition video with crisp surround sound to your hearts content!

If you don’t have an HDMI port on your source device we have a number of converters available to change signal types from the older style signals to HDMI.

HDMI Basics

HDMI stands for high definition multimedia interface and it’s what is needed to get the best quality or picture and sound when using high definition components such as a television, DVD player or game console. HDMI cables run video and audio elements from your device to your television, so you don't have to worry about stringing multiple cords.

HDMI port

HDMI Wall Plates

These days, people are increasingly choosing to use wall plates in conjunction with HDMI connections. Much like a common electrical or phone jack in your house, a wall plate gives you sleek, convenient connection safe from children and pets. With a wall plate near your audio/video source, and a wall plate behind your TV, you can easily conceal the HDMI connection between the 2 behind a wall for a tidier, safer setup. For more information on HDMI wall plates, and wall plates in general click here

Quality is a Factor

There are many different types of HDMI cables, at different prices and different qualities. You don't have to overspend for a quality HDMI cable, but you should take a couple things into consideration. Where is this cable going to be used? If your cable is going to be run behind walls, stretched, pulled, or possibly kinked- look for a durable cable with a strong outer coating. The Sewell Premium line of HDMI cables feature 5 layers of protection for all varieties of cables stress.

HDMI Guide

Length is a Factor

The further an HDMI signal has to travel across a cable the more that signal will deteriorate, giving you a loss in quality. The HDMI standard for maximum length is 50 feet. This doesn't mean you can't go longer, it just means you start running the risk of losing some picture quality when you attempt using longer lengths of cable. To ensure you have a strong HDMI signal, especially over more than 40 feet of cable, we recommend using an HDMI repeater. An HDMI repeater features an HDMI input and an HDMI output, regenerating the incoming HDMI signal before outputting it through the next cable. This will guarantee a strong HDMI signal across long connections.


Anatomy of Our Premium HDMI Cable
Detailed Info and a Cross-Section View of our 4K 60Hz HDMI cable.
By Cameron Postelwait
Anatomy of Our Premium HDMI Cable

HDMI Cable Specs and Performance

ATC-Certified Test Results


First thing's first: how well do our Premium HDMI Cables perform?

Although we can demonstrate our cable's abilities with our HDMI tester (as you can see on the right), it's worth noting that the specs I mention here are not merely from our own test equipment. The HDMI consortium requires cable manufacturers to be graded by neutral 3rd party test laboratories that they call ATCs (Authorized Testing Centers) with a simple pass/fail grading system. Since the HDMI consortium licenses the use of the HDMI trademark and logo, they must ensure that anyone using the word 'HDMI' to market a cable is up to spec, or else people will begin to doubt the standard itself.

It should also be noted that HDMI cable is simply a data cable that passes a large bandwidth, in this case 18 Gbps. For that reason, the 18 Gbps spec is often the main spec you should look for. If it can successfully pass that bandwidth, it means that the cable has been constructed in such a way that overcomes the attenuation and interference problems inherent in data transmission over copper wire enough to pass the stated bandwidth.

That being said, there's more to it than just the cable itself. Since HDMI transmission is simply the transmission of an electric current over a copper conductor, a lot of the success of that signal has to do with the source equipment that is generating that electrical signal. Like with power cables, if you don't have enough juice coming in, you won't get enough juice coming out.

With those things in mind, Sewell's Premium HDMI Cable passes the maximum spec of HDMI 2.0-- with a minimum 18 Gbps bandwidth, our cable supports all of HDMI 2.0's many features in all its lengths (even in long cable lengths that exceed HDMI's distance spec).


Our Premium HDMI cable can achieve:


  • 18 Gbps transmission
  • 4K resolutions: typically 3840 x 2160 or 4096 x 2160 resolution to be exact
  • Can show 60 frames of 4K resolution per second (aka 4K at 60Hz): Quite a bit more bandwidth is required to do 4K at 60Hz compared to HDMI 1.4's 4K at 30Hz. That's twice the number of unique frames per second!
  • Can do 4K at 60Hz with no chroma subsampling: supporting full 4:4:4 chroma: that means it can refresh every pixel's color (in the 4096 x 2160 resolution) every 60 frames every second! 4:2:0 and other subsampled chroma modes are also supported.
  • Can support all the other goodies that are new with HDMI 2.0: 32 audio channels, 1536 kHz total audio, Dual View (2 distinct simultaneous video streams), 4 distinct audio streams, and the new 21:9 aspect ratio.



HDMI 2.0 Cable Test

Multiple Ways to Get to the HDMI 2.0 Spec

Trade-offs between using thicker gauges vs. precision manufacturing


When it comes to HDMI cable construction, there's not just one way to get full HDMI 2.0 specs.

One way is to beef up the thickness of the copper conductors inside the cable. This is often the more cost-efficient way to get higher bandwidth out of a cable because improving the manufacturing process is a much-higher upfront cost. The cost of the extra copper is often small compared to the machinery required to make high-precision cables.

The drawback however is that a cable with thick conductors will not be easy to bend and snake through conduits or behind walls. A thick cable is also heavy and puts unnecessary torque on the HDMI ports of your expensive equipment.

Another method that is even less expensive than using thicker conductors is to put fibrous filter material down the middle of the cable to try to lessen interference and crosstalk. This method has the same undesireable concequences of rigidity and heaviness.

The alternative method of higher-precision workmanship with purer materials allows for thinner gauges and an improved user experience, but how exactly does this work?




Natural Forces Conspire Against Copper Conductivity


To understand the construction techniques that enable superior electrical conductivity, let's first explore what exactly prevents good conductivity.

Electro-Magnetic Interference (EMI)

Do you live near power lines or work under flourescent lights? If so you probably experience a good amount of EMI everyday, but you can even encounter EMI when out in nature. Both man-made and natural objects can disturb the electro-magnetic profile of a space, and these waves can corrupt your HDMI signal (or any other electric signal) while it travels along the copper conductors of your cable.


Crosstalk is essentially the self-inflicted interference that a cable can create because it is sending a variety of different signal frequencies down many conductors in a tightly-wound cable.


Besides the interference that comes from outside a copper conductor, the conductor itself will always resist conductivity to some extent which is unavoidable. It's a similar concept to how we encounter friction with every surface we touch. Friction exists in the world of conductivity as well, and the less pure the copper is, the more friction there is for a signal to travel down that conductor. This resistance is measured in ohms.



Precision Manufacturing and Pure Materials Overcome These Forces


Like I said earlier, you could potentially increase the size of the conductors in the cable in order to battle against all of these natural roadblocks. Fatter conductors support higher MHz rates for the travelling signal making the signal more robust against many kinds of interference and attenuation. The result however is a heavy and rigid cable that is hard to manage.

Comprehensive shielding is a great way to keep the cable thin while deflecting EMI. EMI can be categorized into two main camps: low-frequency and high-frequency. This simply refers to the number of waves the interference produces within a certain space, and different styles of shielding are better for deflecting different frequencies of EMI. The foil shielding is good to deflect the tight high-frequency EMI waves and the braided shielding is better at deflecting low-frequency EMI. Put together, they form a formidable wall against outside forces.

Shielding can also mitigate crosstalk which is why we shield every twisted group of conductors with their own foil shielding.

An even better tool to fight crosstalk is precision-twisting the internal conductors in such a way to cancel out conflicting interference radiation coming from the conductors. It ads no girth to the cable while effectively minimalizing any possible signal leakage.