[Rob]

The cable used by ntl:telewest for the feed from the street is usually a higher quality than the average co-axial used for standard terrestrial feeds. It's that standard cable you've probably used to redistribute the STB output around the house.

Sometimes that cable will suffice, but it's vulnerable to interference and other loss of signal quality that means the STB doesn't get what it needs in terms of input.

The feed to the STB also needs to connect directly to the junction box, street cable termination point. Any additional joints i.e. where your current STB is located, can also affect signal quality.

In short, if you want a second STB, you need a second cable run around your house.