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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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Sunday, 30 November 2014
Neil Bell

2:15 PM

Hi David I couldn't find the KDL-50W68xA model on the Sony website but it maybe academic. The only issue I'm not certain of is if the optical/TOSLINK output you are using from the TV to your soundbar can be used for a Digital to Analogue converter at the same time but I'm sure jb38 or MikeB will have the answer. I am fortunate in that my older Sony TV has analogue audio phono outputs which I feed in to my HIFI amp & so don't need a D/A converter YET!

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Neil Bell's 106 posts GB flag

6:58 PM

David Hobbs: OK - I remember the Sony 50's from 2013 - KDL W656/653 or something similar (which looked very different from the Panasonic 50in TV even though they were using the same LG panel).

Two HDMI's (I said the time it was bit skimpy in this regard..), digital optical, scart, component (YUV) and composite connections (combined, but inputs) and a 3.5mm jack.

The F450 isn't a model we sell, but Samsung soundbars tend to have much the same connections - HW-F450 2.1 Channel 280W Dolby Digital HDMI Soundbar - Samsung UK

HDMI, digital optical, and what might be a 3.5mm jack.

I think JB38 is right - God knows why there is a problem with the BT box when using the scart for audio, but apparently it doesn't like it. Your setup is fine - HDMI to the BT box, and the other to be left for the Blu-Ray. Digital optical to the soundbar.

Personally, I'd go for the cheapest and easiest method - 3.5mm jack to left/right phono's - 3.5mm Jack to 2 x RCA Phono Audio Cable Gold 1m Lead: Electronics - these are an example, and you can spend a pound, or six pounds, they should work OK. The phono's go into the back of the loop box. Look at the audio settings - on a Sony, you can have one stream going to the 3.5mm jack, and hence to the loop, and another going to the digital optical. This means that if your listening on the loop, the soundbar is off (but that makes no difference) and vis versa. On other makes you have to tell it which one you want to use, which wouldn't be the end of the world, but rather than switch it over each time, it should just do it.

There is a sneaky way of checking if this works. The soundbar also has a 3.5mm jack. Get a cable with one of these at each end (Poundland will have them), and see if it outputs on both optical and 3.5mm (you can try one at a time). Then try it with each bit of the system (TV, BT box, etc) - hopefully you should get all sound through the soundbar if its connected up via 3.5mm jack. Swap out that cable for the one which connects to the loop, and hopefully it should all work.

Let us know how you get on. Its a shame you dont have a third HDMI - you could have driven the soundbar via the HDMI in theory, but I'm sure the setup will work fine. Neil Bell - your TV must be about the last year that they still had phono outputs on the back - I suspect they assumed people were largely using digital optical or HDMI. If your analogue, well, they supplied something...

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MikeB's 2,579 posts GB flag

7:01 PM

Neil Bell / David Hobbs: I personally, would prefer to use a powered TOS link splitter such as the type seen on the link, as non powered types, albeit it very low cost, are inclined to be somewhat erratic in operation because of their attenuation effect on the signal output level, hence why so many varied reviews are seen from the users of these devices on places like Amazon etc.

LINDY 2 Way TosLink Digital Optical Audio Splitter: TV

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jb38's 7,179 posts GB flag
Neil Bell

11:30 PM

I think jb38's toslink splitter looks the best bet because the headphone socket would be affected by the volume control.

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Neil Bell's 106 posts GB flag
Monday, 1 December 2014
David Hobbs
11:08 AM

Hi Neil, my mistake. It's Sony TV : KDL-50W685A. Cheers everybody. It's a mine fields of info, so will try them thanks

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David Hobbs's 13 posts GB flag
David Hobbs
2:06 PM

Thanks jb38, will look up the link for splitter. Thanks for all the help . Cheers

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David Hobbs's 13 posts GB flag
Neil Bell

2:15 PM

Hi David Ta for that
I Had a quick look at the HTML manual for your TV and as you were you won't need a D/A converter. You can find it on line:-

Audio cable connection

or on the iManual on your TV- Basic Operations, Using Other Devices, Audio Cable Connection

There is a headphone type socket at the lower centre of the back of your TV and you can use a cable with 3.5mm headphone type plug on one end and 2 phono plugs at the other end to plug in to your loop device. You then need to go in to the menu system to set it to Audio Out and to set the output to 'Fixed' for a line output or 'Variable' so the volume through your loop will be controlled by the TV remote.

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Neil Bell's 106 posts GB flag
Neil's: mapN's Freeview map terrainN's terrain plot wavesN's frequency data N's Freeview Detailed Coverage
Thursday, 4 December 2014
David Hobbs
9:52 AM

David Hobbs: hi, I have connected the 'headphone' type 3.5mm cable with jack pluged into loop box and red/ white connected to lower back of TV and setting changed to Audio out & fixed, but no luck, no sounds on BT vision box? I have kept the scart connect and can hear on TV.

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David Hobbs's 13 posts GB flag
Neil Bell

3:35 PM

Hi David Hobbs It seems as though you have it the wrong way round. The 3.5mm jack should be plugged in to the audio out socket on the lower centre back of the TV and the red & white phono plugs should be plugged in to the right & left line inputs on your loop box

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Neil Bell's 106 posts GB flag
Neil's: mapN's Freeview map terrainN's terrain plot wavesN's frequency data N's Freeview Detailed Coverage
David Hobbs
4:45 PM

David Hobbs: there is only 1 jack input and 1 mic input on the loop box, also I have only 1 Audio output at the centre back TV which I am using for theSamsung sound bar!

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David Hobbs's 13 posts GB flag
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