A patchbay is one of the most useful additions to any recording studio, regardless of the size, as it provides a convenient way to make connections between various pieces of audio equipment without having to rewire your gear each time you need to make one change. The top row of jacks are for outputs, and the bottom row of jacks are for inputs. How the patchbay routes the signal is called normalling. Outputs (top jacks) are connected to inputs (bottom jacks) until a patch cable is plugged into the corresponding front jack. There are three common ways a patchbay, like the Samson S Patch Plus, can configure the signal routing: full-normal, half-normal, and non-normal (called Thru on the S Patch plus).
In full-normal mode, the signal from the top rear jack is sent to the lower rear jack. When you insert a jack into the top front jack you “break the normal” and the signal is sent out of the top jack, but is now disconnected from the bottom rear jack, with the bottom front jack providing the direct connection to the bottom rear jack.
Half-normalled is commonly used for mixing console Insert Points. In Half-normalled mode, the signal from the top rear jack is sent to the lower rear jack. When you insert a jack into the top front jack you DO NOT “break the normal”, so the signal is sent out of the top jack and is still connected to the bottom rear jack. This allows you to split the signal without interrupting the direct connection to the bottom rear jack.
Non-Normalling or Thru
When a patchbay is non-normalling, the rear top jacks (outputs) do not feed signal to the corresponding rear bottom jacks (inputs). The signal from the rear top jack is connected straight through to the front top jack, and the signal from the rear bottom jack is connected straight through to the front bottom jack. Differently grounded equipment share no connections or ground.