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Connecting it all up

Why are there so many sorts of connecting cables? Find out with this quick guide.

Why are there so many sorts of connecting cables?  Find out wit
published on UK Free TV

Why are there so many sorts of connecting cables? Find out with this quick guide.

The connectors on each cable are called plugs (and are also called male) and they will usually fit only into one sort of socket (or female connector).

Most cables you will come across are male to male. Occasionally you will find leads with a socket on one end and a plug on the other, and these are called "extension cables".


The SCART cable is used to connect a set-top box to a television set, or to a video recorder. This can only be a short cable. The SCART cable carries all of these types of signal:

  • analogue stereo sound
  • a single RGB television picture
  • a single composite video picture
  • a single S-Video video picture
  • widescreen picture signal

As stereo sound, RGB picture and widescreen signal is the best possible combination for digital television viewing, it is vital to use a SCART lead between any set-top box and the main television.

The composite video picture with stereo sound is the best combination for a VHS video recorder. If your set-top box has two SCART sockets, it is likely that the one marked TV will carry RGB picture information and the other will not.

If your television has more than one SCART input, you may need to choose a special one (marked RGB) if you want to use RGB from the SCART cable.

On most set-top boxes it is possible to turn the RGB output on and off. This can be used to test the RGB input function on the television ? the picture quality appears blurred when it is disabled.

If have a DVD player, rather than a VHS recorder, you can attach this to the set-top boxes second SCART connector. The signal from the set-top box will normally be overridden by the DVD player when it is on, usually in high-quality RGB.

Some very cheap SCART cables do not have all the pins connected. They may not provide RGB and widescreen picture signals. SCART cables are normally no more than three metres in length.

UHF lead

The UHF lead is a lead that you would traditionally associate with television signals. They can carry:

  • up to 45 (but normally only five) analogue television channels
  • a single picture from a set-top box
  • around 50 analogue cable TV channels
  • mono sound
  • NICAM stereo sound
  • Teletext services (for example, Ceefax)

You can't avoid these cables if you are going to use Freeview, as these cables are the only ones that you can use to distribute Freeview signals around the house.

Where you have an integrated digital television (an idTV) you just need to get the signal from the aerial to the television with one of these cables.

If you are using a Freeview set-top box, you will need to get the signal from the aerial to the set-top box using this aerial lead, but for best results connect the TV to the box with a SCART cable.

You can also use a UHF lead to connect a set-top box to a television somewhere in the house. Your set-top box will require a RF (radio frequency) modulator. Note that "RF passthough" is another way of saying there is no modulator. You will be able to "tune" the second television into the picture showing on the set-top box.

Some boxes (all Sky boxes) have the ability to connect a remote control receiver to the second TV end of the interconnecting cable, so you can change channels.

The set-top boxes, whilst providing a reasonable quality picture to the second TV, will always provide only mono sound via a UHF lead.

The step-change in picture quality obtained by switching to RGB on a SCART is far greater than any obtained though spending any more on a gold-plated SCART cable.

Satellite or cable TV cable

These cables are usually very stiff, and have a very basic screw connector on the end. Usually they will provide an unbroken link to the satellite dish. At the dish end they plug into the device on the end of the arm, the LNB.

Don't try to disconnect these cables when the set-top box is on. Usually there is a small voltage that will cause dangerous sparks.

If the cable connects to a satellite dish, there is not much you can do with the cable. Each receiver in the set-top box needs it's own wire to the LNB. With a personal video recorder (such as Sky+), or a multi-room installations there are two cables to the four-output LNB on the dish. If you want more rooms, each will require it's own cable.

If the cable is providing cable TV, then it is possible to use inexpensive "Y connectors" to link the incoming signal to various set-top boxes, cable modems, or - via an adaptor - directly to the back of a TV.

Composite video cable

This is the most simple and basic video connection you can get. It carries:

  • a single picture from a set-top box

The picture will be in colour, and of comparable quality to a analogue broadcast station. However, there is no sound. For that reason this cable is often found joined to a stereo audio cable.

These signals are quite robust and can be carried for many metres. Often modern television sets have a single yellow photo input on their front input panel.

You also use an identical cable to carry digital stereo (SPDIF) sound.

Stereo audio cable

These cables carry the left and right channels of sound on two joined cables. They are usually required when a SCART cable is not being used, as the SCART cable already carries stereo sound.

If you are connecting your set-top box to an external stereo system, a separate stereo audio is used.

There is no real practicable limit to the length of these cables, but excessive length will degrade the quality of the signal.

S-video cable

The S-video standard is not well supported by most UK digital TV boxes, and very few have a S-video socket. If you need one for a particular analogue camcorder, use it, but avoid S-video with digital television. If you are using what appears to be a monochrome picture from a SCART lead, it will certainly by an incomplete S-Video signal and you should change to the RGB input.

VGA cable

This is the cable you will use to connect a computer to a old style monitor, and some modern LCD screen too. Most modern LCD TVs will have a VGA input too.

If you want to connect a set-top box to a LCD monitor, you can buy a conversion box from around 60. However this will not result in a better picture than using an existing SCART socket if there is one.

The only way to get higher than normal television resolution is to use a VGA in conjunction with a personal computer or modern games console.

DVI cable

If you want to get the very best out of a television or monitor use a digital video interconnect (DVI) cable.

This will be the only way for most televisions and monitors to receive high-definition pictures from a computer, and some set-top boxes.

If you can use either a VGA cable or a DVI cable, choose the DVI option.

HDMI cable

If you want to get the very best out of a television use a HDMI cable.

This will be the only way for most televisions to receive high-definition pictures from set-top boxes.

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Saturday, 29 November 2014
David Hobbs
5:51 PM

MikeB: the loop is what best describe a cable runs around the room next to the skirting board under the carpet and plug into AVX PDA 100 box. The scart is connected from this the TV : a Sony Bravia 2013.

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David Hobbs's 13 posts GB flag
Neil Bell

6:45 PM

David Hobbs Like MikeB I'm not familiar with induction loop equipment either but looking on line it would appear that your AVX PDA 100 has a line input and because modern TVs don't have line outputs via phono sockets then your AVX PDA 100 has to use an output via SCART which picks up just the audio output. It would be helpful to know the actual model of your Bravia TV so we can check this out. As MikeB says you should use HDMI leads to take the video and audio signals from your BT Vision and Blu Ray boxes in to your TV and then whatever is coming out of your TV speakers should be coming out of the induction loop connected to your AVX PDA 100. Do you have anyone around who could check if audio is coming from the speakers?

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Neil Bell's 106 posts GB flag

7:52 PM

David hobbs I have a loop system as i am deaf too... there are 3 types of connections Phono ( RCA)red and white plugs or scart connector or a small headphone line in socket. My loop is wired via my stereo amp so my HD tv, youview,Blu Ray is connected to my TV.. my Panasonic using HDMI leads set allows me to output anolog sound to my amp using a lon g phono cable to my all works well only need to select tv source on the set itself.

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rob's 171 posts GB flag

7:54 PM

I hope this makes sense please do ask if not sure :-)

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rob's 171 posts GB flag

7:59 PM

David Hobbs: When I saw your question, I was at work, and saw a useful thread on AVforums (which I cannot find now!), which asked a similar question.

Neil has spelled out the problem - modern TV's dont use phono outputs. However, there are two solutions.

Fortunately, you have a Sony, which means you can 'split' the audio signal between the speakers and another output, in this case the 3.5mm headphone jack. A cable you can buy for a pound takes the audio from the 3.5mm jack, and converts it into red/white phono at the other end. Since its a Sony, you dont end up with nothing if you plug in the 3.5mm jack (like Samsung & LG), but you do have to tell it to split in the audio setup. Of course, leaving it to take all the audio to the 3.5mm jack is fine in your case.

The second workaround (which we found out when someone used headphones, but only afterwards told us after he'd bought a Samsung) is to use the digital optical output, and connect a digital optical cable to an Digital/Analogue Convertor (DAC), and then use phonos. Needless to say, the first route is much much easier!

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MikeB's 2,579 posts GB flag
Sunday, 30 November 2014
David Hobbs
10:40 AM

David Hobbs: the TV is a Sony Bravia LCD Smart 50inch 2013. The scart is connected to TV, I have HDMI lead from Vision box to TV but no sounds on loop if watching on BT Vision! I also have a Samsung sound bar/ woofer connected to TV, this worked.on both TV & BT box. I am due to received a Sony 3D Blue-Ray / DVD player hence need to understand how to connect my Induction Loop to both boxes to TV ? Thanks

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David Hobbs's 13 posts GB flag
Neil Bell

1:18 PM

David Hobbs

I now don't understand what is happening with your set up. If the SCART socket on your TV does indeed output audio then why would it behave differently when the TV is getting its signals from the BT Vision Box rather than the internal TV tuner? If your AVX PDA 100 is indeed getting an audio output from your TV then it should work regardless of which input is being used by the TV so there is plainly something we are missing here.

What is the actual model number of the Sony TV? How is the Samsung sound bar connected to the TV? Or is it wireless? What is its model number?

The reason we ask for actual model numbers is so that we can look online at the instructions/specifications to see if we can work out what should be happening.

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Neil Bell's 106 posts GB flag

1:24 PM

David Hobbs: Your loop amplifier system is totally dependant on the continuity of the audio output facility on the TV's scart socket your loop amplifier is connected into, anything that upsets it killing the audio, therefore with regards to you having stated that no audio can be heard via the loop from the BT Vision box connected into the TV via an HDMI lead, the question is, can it from the TV's speakers if you lean close to them? because if you can, then this is inclined to indicate that the scart output facility is being affected by input socket selection.

The main point of all this being, that if the continuity of the audio connection is maintained, then it should be irrespective of what you connect into the TV such as the Blue-Ray referred to, as all the TV does is to pass the audio of whatever you happen to be using at the time onto the loop amplifier.

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jb38's 7,179 posts GB flag
David Hobbs
1:43 PM

David Hobbs: Hi Neil, Sony TV model no : KDL-50W68xA, Samsung model no : HW-F450. A cable from sound bar is connected to the back of Sony TV in Digital Audio Out and the Loop scart is connect to the TV (only one) scart socket.. ... I remember when I had the old system of analogue TV , free view & cassette player where I had to connect cables in & out from each boxes to TV, should I do it this way ? Thanks

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David Hobbs's 13 posts GB flag
Neil Bell

2:03 PM

David Hobbs

I think I may have remembered something. My 2010 model Sony Bravia smart TV does have one SCART socket which can be set to output but I think it only worked with the internal tuner and not with another input to the TV so that may be the problem you have with your BT Vision box and that you will have with your DVD/BluRay recorder. Try MikeB's idea first of using the earphone socket if you can find the menu to split the audio output and if that fails then get a digital to analogue converter which takes e.g. an optical output from the TV and provides left & right audio phono sockets which you can connect to your AVX PDA 100.

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Neil Bell's 106 posts GB flag
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