Pro Audio Cables | Cable Properties

Cable Application

Use and description of the cable property and application



Analogue cables are used to transmit low-frequency audio signals and to connect microphones, speakers and many other audio components. 


These cables are primarily designed for transmitting digital signals in the AES/EBU, S/P-DIF and DMX formats. They are designed and labelled with the required surge impedance of 50, 75 or 110 Ω. The S/P-DIF button can identify cables that transmit the S/P-DIF standard exclusively. Please note the surge impedance requirements of your digital equipment, as stated in the datasheets. Almost all of our digital cables can be used as high-quality analogue cables, as well as for connecting scanners, mixing boards, hi-fi components and several other devices in a recording studio.


Every 75 Ω cable is SDI compatible, as long as specific lengths are not exceeded. The decisive factor for maximum cable length is the attenuation at the relevant frequencies; the maximum recommended damping should not exceed 30 dB over a span of 100 meters (9. 1 dB over 100 ft.). The bit rates for HD-SDI are one .485 Gbit/s and 2.970 Gbit/s with Dual-Link HD-SDI (SMPTE372M) and 3G-SDI (SMPTE424M). For 6G UHD-SDI, it’s 6 Gbit/s. 

For long transmission distances, fibre-optic systems are also employed. It’s challenging to make a general statement as to viable transmission distances, as these always depend on the quality of the interfaces in the connected devices. In theory, they can be calculated as follows: 3000 divided by the specified attenuation at 3 GHz for 100 m = cable length in meters. Thus 43 dB would result in a maximum cable length of 69 m. In particular, 3G/6G and 12G-SDI signals are used in the production sector to serve the (future) UHD standard. 


Currently, the buzzword in the television industry is “HDTV“. SCART, RCA or S-video connectors are no longer used for transmission. The new standards are called HDTV (or DVI) and YUV. HDMI and DVI signals can be encoded with HDCP. The playback units and monitors must then support HDCP. Alternately, YUV can be used for a more straightforward transmission, but HDCP signals are not transmitted that way. YUV can be sent with three coax cables, usually fitted with RCA or BNC  connectors. Caution: A YUV signal is not compatible with an RGB signal, even though the three plugs on the units are often red/green/blue. 


In the case of fire, cables marked “halogen-free“ will not develop any gases that are poisonous to humans, such as chloride. This is often a requirement for public buildings. But be careful! A halogen-free cable is still flammable,  and therefore such cables typically require a flame-retardant agent and are then designated FRNC (flame-retardant non-corrosive). 

Smoke suppressant 

If cables or wiring with insulation or jackets containing chlorine burn (e .g ., PVC), dense black fumes will result. Halogen-free cables or wiring only develop about a tenth of the fume density compared to PVC cables or wiring. Thus they are considered to be smoke suppressant.

F R N C 

These cables comply with commonly applicable fire code guidelines. They are halogen-free and flame-retardant. This guideline is classified as FRNC (flame-retardant- none-corrosive). 

EXPLANATION of testing procedures according to VDE 0472, Part 804:  

FRNC Test Type A (⩠ IEC 60332-2-2)  
A cable sample measuring 60 cm (2 ft.) in length is vertically suspended in the centre of a metal box 1200 mm tall by 300 mm wide by 400 mm deep  (circa 47 x 12 x 16“). A gas burner with a defined flame is installed in such a way that its axis is tilted by 45° in reference to the vertical. The fire hits the cable sample about 100 mm/4“ above the lower end. The flame burns until the conductor or the topmost metal shielding shows through, but no longer than 20 seconds. To pass the test, either the test sample must not catch fire, or if it does start to burn, it must then extinguish itself, and whatever the flame‘s heat causes damage must fail to reach the top end of the tested cable sample.

FRNC Test Type B (⩠ IEC 60322-1-2) 
A cable sample measuring 60 cm (about 2 ft. in length) is vertically suspended in the centre of a metal box (1200 mm tall by 300 mm wide by 400 mm deep  (circa 47 x 12 x 16“). A gas burner with a defined flame is installed in a way that its axis is tilted by 45° about the vertical. The fire hits the cable sample about 100 mm/4“ above the lower end for about  1 – 2 minutes, depending on the weight of the sample.  
The test is successful if the test sample did not burn or if the flame that resulted extinguished itself and the damage caused by the heat of the blaze did not reach the top end of the tested cable sample. 

FRNC test type C (⩠ IEC 60322-1-3)  
Cable samples, each measuring 360 cm/14“ in length, are fastened side by side to a ladder-like test rack. This test rack is inserted vertically into a kiln, at a distance of 150 mm/6“ to the back of the furnace. The flame is directed right against the flame samples at the height of approximately 60 cm/2 ft ., at a temperature of roughly 800°C/1472°F, by a burner, about 250 mm/10“ wide. The exposure time is 20 minutes. The test is successful if the ensuing flame extinguishes itself and the damage caused by the heat of the blaze did not reach the top end of the tested cable sample. 
With high-resolution image and video data transmission, in particular, cable performance plays an important role. Products marked with this button allow the high data transmission rate of 10 gigabits per second. 

P U R 

A PUR jacket is extremely tough, exceptionally resistant to the cold (–40°C/–40°F), yet remains easy to wind even at below-freezing temperatures. At SOMMER CABLE, we usually give our cables a halogen-free PUR jacket, which, aside from the advantages mentioned above, is very heat and sunlight tolerant. This jacket is a little more expensive than the standard PUR formulation, but it is now required or preferred by almost all German broadcasting companies and professional installers. 


E30 designates a fire protection class based on DIN  VDE 0815/DIN VDE 4102 (Part 12), which represents improved performance in case of fire compared with standard FRNC cables, for example. In compliance with this norm, E30 guarantees proper cable performance for  30 minutes.  
Please note that it is not possible to manufacture all cables according to E30 or even E90 because the insulation on some wires does not comply with the norm stated above. 


This fire protection class is based on DIN VDE 0815/ DIN VDE 4102 (Part 12) and stands for improved performance in case of fire, compared to standard FRNC cables, for example. In compliance with this norm, E90  guarantees proper performance for 90 minutes.  E90 certification is first and foremost required for power and fire alarm cables. This norm rarely is applied to audio multipair cable connections because the insulation walls on cables designed to have such small diameters are too thin. 


This cable has a unique jacket mixture made of PE that is suitable for underground installation. Please note that a PE jacket does not automatically make a cable ideal for an underground facility because this type of cable must be specifically designed to withstand the pressures underground.
However, all SOMMER CABLEs with this symbol are suitable for underground installation. 


All cables marked with the AQUA button are longitudinally watertight up to 20 bars of water pressure or transversely watertight (AQUA MARINEX series). The special PUR jacket keeps water and other fluids from penetrating the surface and prevents longitudinal dispersion in case of cable damage. The watertight jacket is also robust enough to accept the installation of high-pressure end connectors which are inevitably needed to avoid moisture from entering the cable. 

Due to its combination of a special saltwater-resistant PUR jacket and protective tape, the AQUA MARINEX cable series can be permanently installed underwater. Penetrating water would not only speed up the oxidation process, but due to the effect of capillary, the action would also alter the damping and other relevant electrical values. Here, video cables and other coaxial cable types are significantly affected (e .g. when used for cameras and video monitors).
With orders of at least 2000 m/6500 ft. almost all of our cables can be made with a longitudinally or transversely waterproof jacket. 


The foamed insulation employed in some cables and lines is considered fragile and, under severe strain, will be adversely affected by clamping and chuck strain relief systems. In particular, with XG/HD-SDI video or AES/EBU cables, the resulting attenuation losses may have fatal consequences. Many of these standard lines are unsuitable for permanent flexible use since too many bending cycles will cause the foamed insulation to deteriorate. In these higher-end lines, SOMMER CABLE, therefore, relies on a unique manufacturing process for the insulation called HD-SGS (High-Density Skin/Gas/ Skin). 
Here the PE or PP insulation is physically or chemically gas-injected and then cross-linked, sealed or smoothed both on the outer skin and in the inner core (which is in contact with the copper wire). This procedure yields the best possible electrical values, and these values are retained even under severe strain. 
This cross-linkage was even implemented into the carbon screen in our SPIRIT LLX high-end guitar cable and the  ASTRAL LLX high-end SAT cable.

O F C 

SOMMER CABLE primarily uses oxygen-free (OFC) or low-oxygen copper. For your information: Copper has a specific resistance of 0 .0178  per meter at a  cross-section of 1 mm²/AWG17. The purer the metal,  the smoother it is (high bending cycles!), and the more consistent this value will remain over the years. 


The Pur Master Blend is a cable jacket formula based on a polyurethane component specially developed for SOMMER CABLE. The jacket on the PMB  can handle abuse and the cold (–40°C/–40°F) and is free of adhesion with a surface that is easy to clean. 
PMB offers the toughness and temperature resistance of PUR and the flexibility of PVC. PMB is not halogen-free or flame-retardant.


This jacket is a granular blend based on a PVC formula developed exclusively for SOMMER CABLE. S-PVC is a super soft PVC with the feel and flexibility of a soft rubber cable, but significantly more resistant to notching and cold temperatures than most standard PVC jackets.  While most cable jacket mixtures already start tearing during mobile application in temperatures of –10°C/ –14°F, the S-PVC withstands temperatures of –30°C/ –22°F. 


This is a specialised procedure used by SOMMER CABLE to compensate for the typical tendency to bend created automatically during the stranding of multipair cables. Simplified this means: To produce a torsion-free cable, expensive and complex stranding machines are needed to counter-strand outer pairs against the core. Doing so creates a multi-conductor cable that can be wound a thousand times or twisted into a figure-8 without knotting or buckling. All multipair cables identified with the X-TORSION logo are suitable for extremely high bending cycles (e .g ., floor cables). They are recommended for professional broadcasting and event technology.