AUDIO VISUAL CABLES – USES AND LIMITATIONS

When planning your AV installation there are so many different things to think about it’s super easy to overlook a major flaw in your design so we’re publishing a series of blog posts giving you some helpful tips and tricks to remember when planning your installation.

We expect that one day everything will connect wirelessly with no issues or connection problems but sadly, that day isn’t today. For stability and reliability, we suggest using wired connections for video and audio connectivity. I have included some examples of different cable types and their maximum distances in the following blog post.

I will now take you through different connectors and cables and their limitations.

HDMI

HDMI or high-definition multimedia interface is commonly used for high definition digital video and audio connections. Unlike other signals, HDMI has embedded digital audio which means audio and video are sent down the same cable, rather than having 2 or 3 different cables to achieve the same result. This is helpful when connecting a Blu-Ray player or laptop to a screen or projector.

HDMI is found on all new and most recent televisions as the main video input.

When using HDMI the recommended length of cable is anything below 10 meters ( 32.8 Feet) to prevent signal loss. You can purchase longer stand-alone HDMI cables but depending on the quality of cable and the resolution that you are transmitting you may find that they don’t work for you. There are other guaranteed methods to extend an HDMI signal over longer distances without signal loss.

Cat5E/ Cat6 extenders is a common way of running HDMI over long distances. At AV Unit, we use “HDBaseT” to extend both HDMI and ethernet control over up to 100 meters using a single Cat6A cable. More information on HDBaseT and what it can do can be found here. We also offer a range of Kramer HDBaseT products in our hire catalogue which can be found here

HD-SDI

HD SDI or high-definition serial digital interface cables can be an alternative option to HDMI. HD-SDI can carry high definition video signals over longer distances depending on the type of cable used. SDI cables use the BNC type connector so they twist and lock into place which is superior to HDMI because it allows connections to be secured which will reduce connection problems. The big difference between HD SDI and HDMI is HD SDI is not considered to be a mainstream consumer / domestic solution so it isn’t as readily available and is therefore considered to be a professional/commercial option.

Although the cable is cheaper than HDMI and can run longer distances, you may need additional converters and adapters to make it work with most conventional video equipment like display screens or projectors.

HD SDI is commonly used with video cameras, CCTV cameras, commercial display screens and projectors. If your device doesn’t have an SDI input/output there are plenty of options to convert HDMI to SDI. A great example and the industry standard would be a product from BlackMagic.

The distance for HD-SDI is totally dependent on the type of cable used. Our Belden 1694A is rated at 84m for an HD signal. There are cables that will go up to 100m, but this is much more expensive than standard SDI cable. VanDamme offers a range of flexible cables, which are much nicer to work with but this cable can’t be run as far. SDI is also often used to extend HDMI connectivity. We have a range of HD-SDI cables available in our hire catalogue which can be found here.

DVI

DVI or digital visual interface are capable of transferring high definition digital (and analogue) video signals and are commonly found on most Computer outputs and monitor inputs. DVI uses two threaded pins to lock the connector in place, which keeps it secured and stops the cable from disconnecting unintentionally. There are a few different types of DVI on the market so it is important to ensure you choose the right cable to fit your needs.

DVI-D (‘D’ IS FOR DIGITAL)

DVI-D is the most common version of the DVI connector that you are likely to find on your devices.

A DVI-D connector can interface HD video signals between two devices (for example, a DVI-D cable can connect an HD laptop to an HD projector).

You can also convert other video connectors to DVI. The best example of this is using an HDMI or Displayport video output. Both can be converted to DVI however, the DVI cable itself does not support the same additional features as the other connectors. For instance, a DVI cable is not able to carry audio signals as an HDMI cable would. So when should I convert to DVI if it doesn’t have the same features? A standard DVI cable can run at full HD for a recommended length of up to 10m but run longer distances with higher quality cables. DVI-D cables can also support either single and dual-link DVI which is commonly used in equipment that outputs higher resolutions.

SINGLE LINK DVI AND DUAL-LINK DVI

What’s the difference? Single link DVI connectors and cables are only capable of producing a resolution of up to 1920 x 1200 pixels at 3.96 Gbits/s whereas dual-link DVI can produce a resolution of up to 2560 x 1600 pixels at a higher bitrate of 7.92 Gbits/s which means you will get a much sharper/ crisper image at a higher resolution than full HD.

DVI-A (‘A’ IS FOR ANALOGUE)

DVI-A is the analogue version of the DVI connector. You are unlikely to find these connectors on any recent devices as they carry the same analogue signal as a VGA cable with a maximum resolution of 1280 x 720. The caveat to this an analogue DVI connection can run longer distances than its HD counterpart because it’s carrying much less information from A to B.

We have a range of DVI cables available in our hire catalogue which can be found here

DVI-I (‘I’ IS FOR INTEGRATED)

A DVI-I interface is one that can be either digital or analogue. For example, some TVs use this type of connector and within the TVs menu you can set it to be either a digital or analogue input. Most DVI cables have all the necessary pins and wires connected to allow for transmission of either type of signal.

VGA

VGA or video graphics array cable is used to send analogue video signals to devices such as computers, projectors and monitors. VGA connectors use two threaded pins to lock the connector in place, which can be useful to keep it securely connected.

VGA connectors are considered old hat and are being replaced by HDMI and displayport connectors for digital signals. A few years ago it was common for laptop computers to have a VGA port connector whereas no you would be hard pushed to find a new computer with such a port.

We recommend that a VGA can run for up to 40 meters without problems because it’s carrying less information, again you can extend a VGA cable over much greater distances by using an active extender to extend the signal over cat5e/cat6 cables. We have a range of VGA cables and extenders available in our hire catalogue which can be found here.

USB 2.0

When using USB peripherals the preferred cable length is up to 5 meters (16.4 Feet) but again there are solutions around this to be able to get long cable runs!

A good example of where we use USB 2.0 is for our interactive touch screens. The USB cable gives us the ability to control a computer using the touch screen interface. However, only having a maximum of 5 meters of cable to link a laptop and a touchscreen is a very restrictive problem.

When installing a touchscreen in a school environment, the teachers will often have their desks set away from the whiteboard which means we need to extend the USB. Similar to the HDMI extender, the USB 2.0 can be extended using a Cat5e extender over long distances or a passive cable extender for much shorter distances. Lindy offers a range of extenders (over Cat5E/ Cat6) as well as passive cable extenders, which can be extended for up to 56 meters! USB 2.0 transfer speed is up to 480 Mbps.

USB 3.0

Just to add to the confusion, there are different types of USB! So how do you recognise the difference between a USB 2.0 and a USB 3.0? A USB 3.0 has blue connectors as pictured, a USB 2.0 has black connectors. The main difference between the two connectors is the speed at which data can be transferred between two devices. A USB 2.0 can carry 480MB of data per second, whereas a USB 3.0 can transfer a whopping 4.8GB of data per second.

USB 3.0 can run for up to 5m without issues, same as the 2.0 and can also be extended using a similar extender/ passive cable extender options that are available from a number of different manufacturers. You just need to make sure that the extender can work with USB 3.0 to keep up with the higher transfer speeds of required by USB 3.0.

Just remember to use full advantage of USB 3.0 you need a USB 3.0 port on your computer or device (remember to look out for the blue connectors!).

XLR (Microphone cable)

A standard professional grade microphone uses the common 3 pin “XLR” connector. XLR connectors are available with different numbers of pins however, for audio the standard number of pins is 3 after all 3 is the magic number…

In terms of distances, the recommended distance you can run a good quality microphone cable is 250m but there is something very important to take into consideration when planning your cable route.

The closer you are to other cables like mains power the more “noise” or interference you will have on your cable. So even if the cable can run up to 250m without issue, the chances are there will be an environmental factor along the route that will add interference into your audio signal.

There are a few things to look out for to help limit this, however. The first is to make sure the cable you purchase is Balanced or shielded. This means the cable itself has a great way of removing interference from external sources and will greatly reduce the amount of background noise the cable picks up over distance.

We have a range of microphone cables available in our hire catalogue which can be found here

SPEAKON

Speakon cables are commonly used to connect passive speakers to an amplifier. Speakon connectors can vary in how many “poles” they have (or pins to you and me) which starts at 2 for a standard cable but could go all the way up to 8. The more poles you have, the more signals you can send to multiple speakers using one cable.

Speakon connectors are commonly used for temporary installations and on more professional grade equipment due to their twist and lock connectors, which prevent the cable from becoming loose but are also a huge time saver when installing speakers!

The length of cable used depends on your speakers and the amplifier powering them. There is a lot of complicated factors that come into play when planning your cable route for speakers. As a rule of thumb, you can run a fair distance with Speakon cable but you need to try and keep the cable runs short and of similar length. You don’t want to run 10 meters to your first speaker and 100m to your second because there will be a noticeable difference in volume. It’s definitely worth consulting an expert or the manufacturer when planning a speaker installation as there are a lot of factors to consider.

There are lots of other cables and connectors available on the market, but the above are the connections we consider to be the core group you will come across when planning your Audio Visual Installation. It’s important to remember that we have a team of experts at AV Unit who are ready to take your call to discuss any projects you have in mind.

Got an installation coming up you need help with? Tell us what you want to achieve from your next project and let us show you how the AV Unit team can help you create an audio visual solution perfect for your requirements.

CALL US: 01473 705205

EMAIL US: info@avunit.com

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