Half-normal patchbay configuration - Half normalling

A half-normal patchbay configuration is commonly used with analog line level signals. The signal from the source device, at the top jack, flows through to the jack directly below, to a destination device, via the “half-normal” signal route. This type of normaling differs from a full-normal in that the signal switches off, breaking the normal when patching into the bottom jack only.

This configuration also allows the engineer to create a second signal route, while maintaining the half-normal signal route - In effect, a Y cable. An identical signal is created when patching into the top jack, thus not breaking the normal. The top jack can also be used as a monitor jack, allowing quick checks of signal without breaking the normal.  

Breaking the normal by inserting a patchcord into the bottom jack creates no connection between the vertical pairs of jacks. This “broken normal” state is maintained as long as there is a patchcord in the bottom jack. The signal can then be re-routed, as required, in the signal chain.