The SoundTools RAT CAT series of products (CAT Box, CAT Tails, CAT Rack and WallCAT) do rely on a shielded cable. The 9th wire of the shield helps to eliminate hum and buzz while carrying the ground part of phantom power.

We get a lot of calls from people who think their cable is shielded when really it's not, this can cause some signals like phantom power or intercom will not work without shielding. Sometimes a cable will have the metal housing connectors and the cable itself won't have the shield inside of it. Additionally, some cables will be labeled shielded on the cable but they won't use the metal housing on the connectors. Some cables will even have shielded cable, metal housing but the shield is not terminated to the housing.

A few quick ways to tell if your cable is shielded

1. Read the writing on the cable. If it is shielded it will most likely start with an S, F, or U. (ex. S/UTP) Unshielded will start with a U (ex. UTP)
2. Even if the cable is shielded, if the connectors do not have the metal housing the shield will not be utilized.