non-normalled, half-normalled, full-normalled Patchbays

The upper row is always the SOURCE JACK and the lower row the DESTINATION JACK.

non-normalled patchbay, the signal can not be interrupted or monitored

half-normalled patchbay, the signal path can be interrupted and redirected by inserting a plug into the destination jack (lower row), the source signal (upper row) can be monitored without interruption

full-normalled patchbay, the signal path will be interrupted and redirected by plugging a patch cord into either jack

Mosses & Mitchell
Audio Accessories

Patchbay Grounding

To keep ground-loop hum under control, it is necessary to choose one uniform method of interconnecting the grounds / shields of the audio equipment, connected to the audio patchbay.

The typical four types of grounding patchbays are:

ST (Shields Terminated): the shields of each wire are terminated only at the jack terminal. Shield wires do not interconnect from jack to jack

SB (Shields Bussed): each row of jacks has a bus bar that connects all shields from that row, one single ground-wire connects these shields to ground

SS (Shields Strapped): the shield of each top row output jack is connected to the shield of the designated input jack below it, the connection is not interrupted, whether or not patch cables are inserted into the jacks

SN (Shields Normalled): switch contacts normal the shield in the same way as the signal wired are normalled, these contacts allow the shield to be half or full normalled