How important is quality for HDMI cables?

Digital signals consist of 0 (no signal) and 1 (signal). Billions of these 0 and 1 create pictures and sounds. A good quality cable will transmit these signals so that at the end the connected device will recognise these signals accurately.

When using bad quality cables, influences such as cable attenuation, crosstalk and jitters affect these signals so strongly, that the receiver can not create a picture.Bad quality cables influence cable attenuation, crosstalk and jitters, these signals are affected so strongly that the receiver can not create a picture. The display will only remain black. Exceptionally fast data streams required for the display of 1080p pictures can not be transmitted. The receiver then automatically switches to a poorer resolution.

Why does transmedia guarantee the quality of its cables?

Actually, it is not difficult to produce a quality cable, provided that the necessary know how exists. transmedia explicitly uses the best raw material, such as OFC copper. All cables correspond to the HDMI Organisation norm, even for the 2.0 version. This is inspected by our suppliers in Far East in detail as well as from us. As far as we know, we are the only importer of HDMI cables Europe-wide, who possesses the testing systems for HDMI cables. This enables us to determine all criteria for the rating of cables (so called S-parameter) and present an eye diagram.

How to recognise the difference between Good and Bad?

Due to the prices, producers often try to save on the material, therefore, bad quality cables are often thinner. Additionally, raw materials such as copper are substituted by cheap materials such as aluminium or even iron. Not only this, but also cable cross-sections are too small. Instead of using 0,24 mm2, which is obligatory for long cables, only 0,08 mm2 is used – which makes just 1/3 of the material. Many bad quality cables are produced this way.
Depending on the cable’s length, the signals are transmitted so poorly that the resolution is so bad and with long cables these, signals are not even able to create a picture.

The eye diagram is a very important measurement in proving that the monitor accurately recognises the digital nulls (no signals) and ones (signals). The stronger the existing and thoroughly defined free fields are affected or crossed out, the less possibility is for the expected picture to be displayed (see the red streams in the pictures). With a quality cable the free fields are circled generously. No faults can be found. This is exactly the technique our department for incoming inspection control uses for all HDMI cables. Those which do not meet our HDMI standards, fail our tests and are blocked from our system.

The coax cable thing

On the internet a whole lot of coaxial cables with a screening immunity of 135 dB or even 140 dB is being offered.

On closer inspection you will soon discover the term „max“, e. g. 135 dB max or 140 dB max.

We procured ourselves a variety of those cables and checked their screening immunity.

The results show that

- not a single of those cables really approaches the maximum value quoted and
- the lowest screening immunity doesn‘t even surpass a value of 90 dB.
Subject to the corresponding standards (e. g. EN 50289) the lowest screening immunity of the frequency range defined has to be quoted.

Therefore, the description for these cables must not be 135 dB max and 140 dB max. Correctly described these cables would be 90 dB cables, but that’s all.

It is not necessary to use 5 shields for a 90 dB cable. 2 shields of good quality are absolutely enough.

By quoting a high screening immunity and the use of several shields, suppliers of such cables intend to give the impression that the cables are top quality cables – certainly in order to sell it to unsuspecting customers who, however, obtain a medium quality cable, but that’s all.

For example F-plugs

Oftenly we are responded, that some of our F-plugs should be too expensive.

Sometimes the customers have only half price.
We have checked these cheap offers and compared how comes such difference.
Here is the result:

Quality F-plugs are made of brass. The finished F-plug has a weight of about 5 grams. The minimum torque is 3.4 N.

Now to the cheap offer:
Just the first view showing the poor quality. It is not cut material, but simply zinc diecast. The weight is only 2 grams. Our testing of the torque showing only 1 N. This belongs to the material.
With these results we have calculated the price of the used raw material. (Updated 20. Januar 2015)

Price for Cu 5084 €/to 5g = 0,026 €
Price for Zn 1518 €/to 2g = 0,003 Euro €

The price difference mostly belonging to the used materials compared with quality the cheap products doing very badly, as the most important values like the torque are not in line with the norm.

Our tip: take care for quality!

Risky Price Competition: Coaxial Cables

In times of increasing commodity prices, every purchasing assistant aims to buy goods at the most competitive prices possible. And when it comes to the number of items, every single cent counts. In this case, the supplier offering at the most competitive price makes the running.

But have you ever spent a thought on what
you get buying at the lowest price?

The products offered are no longer comparable regarding their quality. Sometimes you might reveal this at first sight, but in most cases, the difference is concealed underneath a nice (cable-) coating.

We have satellite connection cables at our disposal, which are meant to be sold on the German market, but only have a screening immunity of 30 dB. The statutory minimum requirement is 75 dB, yet a screening immunity of more than 85 dB is recommended for the digital technology.

We cut these cables open and what we found was alarming:

A hardly noticeable braid is meant to coat an aluminium foil which itself does not fully coat the dielectric. However, this is hardly possible because the single hanks are not woven tight enough. Neither can you get any shielding with an aluminium foil not coating the dielectric.

The F-plugs are crimped directly to the PVC-coating so that they do not have any contact to the shield. As several emitters interfere with the video signal, these cables are unserviceable. In accordance with the EMC regulations, this cable must not be launched anyway. The state will punish any violation with considerable fines.
How cheap does a cable have to be so that you will still buy it? Actually, given for free it would still be too expensive as the disposal costs have to be paid as well.

For a few cents more you can purchase cables from us which you can sell without any concern and which at the same time will please the customers as they will be spared from any interference.

Our technical know-how helps us to achieve this result. We know the functioning of cables and we also know the way cables have to be produced. Our modern test lab and our engineers see to an optimal quality assurance for all products.

Our advice is: Mind the quality!

SC OCC - Copper

Perfect Picture Quality! Perfect Sound!

Usual copper used for conducting consists of copper crystals of approx. 1 mm size. Every time a signal flows through the copper from crystal to crystal, it increases the total resistance. Additionally, standard copper is impurified with oxygen compounds which also impair the signal. SC OCC copper is made of OCC copper (Ohno Continuous Casting with a degree of purity of 99.9996 %), a long crystalline wire developed by professor Ohno. The wire isn’t drawn to its diameter anymore, but cast, forming an almost monocrystalline structure.
For our Big Series we additionally silver-plated this highly valuable material. Silver is an even better conductor than copper, but is only used for the best conductors and cables because of its high price. Due to the skin effect, especially high-frequency signals in the analogue as well as digital technology only flow through the surface of the conductor and the use of silver ensures a lossless transmission. This material we call SC OCC (Silver Cladded by Ohno Continuous Casting).