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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.

Help with Television sets?
What connections are used from set top box to TV (such as SCART) ?1
If you have several TVs at home do you need separate decoders for each set or is2
Can I use a Freeview box if there is no SCART connector on my TV?3
My TV is NICAM, does that mean I have digital TV?4
Why has my widescreen TV just made everyone look fat?5
In this section
Loft aerials1
Do I need to buy a booster?2
How to receive Freeview on your PC3
Indoor aerials4
Whole house digital TV5
Now and Next6

Monday, 27 February 2017
Neil Bell
10:47 PM

I was curious about Mike B's point about more than one audio output simultaneously so I checked on my Samsung UE40H5500 this afternoon and the act of plugging in headphones does not mute the Toslink signal. It only mutes the internal speakers so you can use both outputs at the same time. We still don't know what Samsung model TV Carole has but if she has an optical output she could use it via a Toslink cable and digital to analogue converter to feed her loop amp leaving her internal speakers for any hearing members of her household.

link to this
Neil Bell's 105 posts Silver Silver GB
Tuesday, 28 February 2017
11:01 AM

Neil Bell: I'm pleased that you can use both outputs (we had a Toslink output to a soundbar at work on the Samsung, but I didn't have time to put in headphones as well), but the real barrier is to be able to use the internal speakers and an output at the same time.

Could you check that, because it would mean that Samsung has entered the modern world, and made life easier for all of us! If not, then an extra speaker would still be needed, but at least the TOSlink could go to an OK soundbar, and the 3.5mm jack for the loop.

link to this
MikeB's 2,179 posts Platinum Platinum GB
Neil Bell
1:16 PM

Mike B Just to clarify, you can use the internal speakers and a Toslink output at the same time. I use the Toslink output via a DAC to feed my HIFI amp so that I listen to the TV through my HIFI speakers and control volume with the HIFI remote. I can also (although of course don't) turn the internal speakers up using the TV volume control OR plug in headphones instead at the same time. My instinct would be to use the Toslink & DAC for the loop amp leaving the internal speakers operating normally. I'm not familiar with sound bars but presumably you could either do as you suggest using the Toslink for the sound bar and the headphone jack for the loop or use a Toslink splitter as recommended by Mike P and have lots of lovely boxes, power supplies and cables although didn't Mike P say the ladies don't like cables? I'm joking of course. Neil

link to this
Neil Bell's 105 posts Silver Silver GB
1:29 PM

Neil Bell: I didn't think you could use the internal speakers and another output at the same time, so the TOSlink/DAC solution works fine. Thanks for the info, because I can now tell customers there is a workaround (which I suspected anyway), but it would be nice if Samsung just looked at the need in the market!

Actually, ladies really like soundbars, because there are few (if any) wires, apart from power ones. Most decent soundbars have the capacity to hook up wirelessly to the same brand TV (so in theroy no need for TOSlink or HDMI), and generally have a wireless sub as well. Thats another reason why Sonos is so popular - easy to use and no wires.

link to this
MikeB's 2,179 posts Platinum Platinum GB
8:43 PM

MikeB and Neil:

On my LG you can only use either the internal speakers or the optical link - but not both at the same time. Likewise, inserting a jack in the head/ear phone socket mutes the internal speakers.

So using the optical to feed both a sound bar/HiFi and via a splitter an optical to analogue converter allows one viewer to listen via earphones or headphones whilst everyone else can listen to the sound from the sound bar.

My late father-in-law was even more hard of hearing than I am and we solved the problem for him in a similar way (before optical links) and he even had his own volume control!

Just takes a little thought.

link to this
MikeP's 1,491 posts Gold Gold GB
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