Patchbays are used to re-route input and/or output signals, and sometimes to split them (send them to two different places at once). A patchbay can save you hours of time (and possibly your sanity) when recording and mixing.
For starters, imagine a typical recording session, where you're hooking up your compressor to control the input dynamics of your guitars, vocals, etc. into your recorder. Now it's time to mix down, and you want your compressor between your multitrack recorder and your mixdown recorder, OK, a few things to replug. Now you have to do a retake and switch all the wires again...!! Using a patchbay will hold the time here down to 45 seconds.
In reality, of course, you have effects, sweeteners, and all kinds of other things to change around, so the time savings -- especially as you're probably the producer, engineer, and musician all at once -- is pretty great. But while you're saving up for one, remember this quote from Star Trek 4:
That is, the patch bay will cost money, but the patch cords/cables you'll need to hook everything up won't be cheap either! Count on spending around $200 minimum before you're through, because everything on a patch bay gets hooked up twice: once in back (and if you do it right the first time, only once!) and again in front, where you can quickly make all your changes.
Here's a great
page that shows pictures, schematics, and even how to build your own
(although personally I think you will put in dozens of hours of work and
save maybe $10, but some folks have less money than time).
The Following Original Article is by Jay Rose
Q: I'm sure it's a simple thing, but can someone explain the path of the signal when using a patchbay both normalled and non-normalled?
A: Think of the headphone jack on a boombox or TV. The speaker is wired through it. When phones are plugged in, the speaker cuts out.
A normalled jack works the same way. An effect output (for example) is wired to a jack, and then to the return input on your board. With no plug in the jack, the effect goes right to the board.
But plug in a patch cord (for instance, you want to send the effect's output to a compressor) and the connection to the board is broken.
That's a simple single-normal wiring. In a schematic, it looks like this:
EFFECT OUT ---------\/ (the plug goes in here) ---- | | TO CONSOLE----------
The plug connects to the "v" part, pushing it away from the contact that goes to the console. With no plug, the circuit is completed within the jack.
Most patchbays are wired "dual normal": in our example, there'd also be a jack for the effect return. Its normal is connected to the effect's normal. Plugging into either hole breaks the connection.
EFFECT OUT ---------\/ ---- | ---- TO CONSOLE ---------/\
Some equipment is wired "sniff" or "half-normal". The effect's out could be tapped at the top jack, but it would still go to the console. Plugging another effect into the console's input, however, breaks the connection from the effect.
EFFECT OUT -------x-\/ | | ---- TO CONSOLE ---------/\
And that's all, jacks.