Patchbays are one of the things that tend to separate a project or home studio from a commercial one. If you feel like you need one and the flexibility it allows, you probably already invested a non-negligible amount of money into your gear and you're moving forward. So.. congrats! Patchbays are awesome and fun to work with.
The convention is that the top row is where the outputs of your gear come out and the bottom row is where you input the signal into them. For example, the outputs of your mic preamps should be plugged into the top back row and the inputs of your digital converter into the bottom back row. Signal flow depends on how your patchbay is normalled. There are three modes:
- full-normal means that the top and bottom rows are connected but that connection can be broken if a cable is plugged into one of the front jacks
- half-normal means that the top and bottom rows are connected but plugging a cable into the bottom row breaks that connection and plugging one into the top row splits the signal (without breaking the connection)
- non-normal means that the top and bottom rows are not connected and require front connections to be used.
The idea is that you can have default routing paths set automatically by using full or half normal modes but also be able to change them with patch cables and use different combinations of gear. Think of the previous example: preamp outputs would automatically go into converter inputs... except when something is plugged into the front !
Another important aspect is with regards to plugging microphones that need phantom power into a patchbay. Some manufacturers/models do allow for that and some don't. Be sure to check if yours does. There are some classic horror stories of those 48V hitting some innocent input when a patch cable is unplugged too eagerly. A good tip is to always be safe and turn phantom power off before unplugging the respective patch cable.