Today, we learned about the 4 patch bay configurations:
Open shows that signals flow straight through the bay with no interaction between the top and bottom rows at all. You might use this configuration for connecting the ins and outs from the back of an EQ or compressor unit to the patchbay so that they are easy to get to from the front of the bay. Most important to notice here though is the strict patchbay convention of outputs on the top row and inputs on the bottom row.
Parallel shows that the top and bottom rows not only pass their signals between the front and back but also from the top to bottom. It doesn’t matter what you plug into the front panel this internal connection will remain. This is used to split one source signal to many destinations.
A Normalled section automatically routes whatever is plugged into the top output of the patchbay to the input directly beneath. So, imagine that you have wired a compressor to a normalled socket. The usual way of laying it out on a patchbay would be to have the outputs above the inputs. If these were normalled this would create a feedback loop as the output feeds the input, which feeds the output, which feeds the input ....etc. For this reason normalling is used for connecting equipment where a signal flow is required (e.g. a mixer’s direct outs to an audio interface’s inputs) as you don’t need to insert a patch cable every time you want to use it. You can still break the connection by inserting a patch cord into either the top or bottom sockets enabling you to re-route the signal.
There are obvious similarities between this and the normalled setup. The only combination that differs is number 2. Notice that when a plug is inserted into the front panel top row that the connection between the top and bottom row is not broken, the plug hears (commonly referred to as “sniffs”) the signal without interrupting it. This feature is what makes this configuration so incredibly versatile in the studio.