Types of Patchbays
There are three standard types of audio patchbays: RCA, TT, and 1/4" TRS. Patchbays made with RCA connectors can not handle balanced audio, and therefore aren't really a good option if you have even one piece of balanced gear (like a microphone preamp). Most RCA bays are also limited by a closed design which keeps the user from being able to obtain some configurations, which I'll explain in a bit. TT, or tiny-telephone (also called "bantam"), bays have roughly four times as many connectors per inch as 1/4" bays, and therefore can achieve lots of interfacing in minimum space. Most TT bays have jacks on the front and solder points on the rear, allowing the user to set them up any way he or she desires using only a soldering iron. 1/4" bays are considered more rugged by many users, and though physics says there will be only one point of contact between a round plug and the flat contacts inside a bay, some folks feel that the larger 1/4" connectors sound better due to increased contact area. Try them both and see what you think. 1/4" bays are available with jacks front and back (easiest setup, limited options) and jacks front and solder points back (more involved setup, most options). Some 1/4" bays look like they'll work well with standard guitar cables, but are actually designed for MIL-type 1/4" connectors that have rounded heads rather than the pointed tips of most guitar cables. Guitar cables will work in a pinch, though. Good patch cables for either type of bay are expensive, starting around $10 per cable for a 1.5' patchcord. If you are in an abusive environment, buy cables that are repairable; cables with molded ends don't give you many repair options should something go wrong inside the connector. On the other hand, I have some ADC TT patchcords that have screw terminals inside the connectors, and I occasionally have to open them up and tighten the screws to keep them going. Monster, Mogami, ADC, Neutrik and Switchcraft all make good patchcords in a variety of styles. Contact info for any company mentioned by name is at the end of the article. Some folks prefer the sound of brass contacts to nickel, but brass tarnishes and needs to be polished (try Brasso), nickel stays clean. Monster's patchcords are gold plated. Again, make your own call by listening to your options. Everything contributes to the sound of the final product!
Inputs and outputs
I highly recommend getting a patchbay that allows you to solder your own rear panel connections. Not only will you become really familiar with the bay layout, but you'll improve your soldering skills, get used to the idea of fixing things, and become one with the signal flowing through your studio. Bays with solder point backs allow much more flexible configurations, and save mightily on connectors compared to bays that have jacks front and rear.
It's up to you to find out whether the gear you'll connect to your patchbay can play well with others. You'll need to know that transformer balanced outputs feeding unbalanced inputs are guaranteed to lose level, and depending on how you wire your bay, may not work at all! Unbalanced outputs from consumer devices like CD players don't have the juice to drive most professional balanced inputs as they're at a disadvantage both in terms of impedance and level, you'll get signal, but plenty of distortion, too. User manuals can shed some light on interfacing specific gear, and other good connection advice is available from Rane (Rane Note 110, available online), Jensen Transformers, and from books like Yamaha's Sound Reinforcement Handbook (ISBN# 0881889008).
When starting from scratch try to use the best cable you can afford: Monster, Mogami, Canare, Belden, Redco and many other companies make great wire. You'll need two conductors plus a drain wire to do balanced connections to a bay, just like mic cable. If you're in an area that's subject to RF interference, try using the slightly stiffer cables with a foil shield, as the conductors will be fully protected, rather than cables with a "served" (wrapped) or braided shield which are extremely flexible, but don't offer 100% coverage. Use the best connectors you can afford also. My preferences are Mogami wire terminated with gold plated contact Neutrik XLRs, Neutrik 1/4" Tip-Sleeve and Tip- Ring-Sleeve connectors, and Canare RCA connectors. Neutrik has really good strain relief in all their connectors and their XLRs are easier to solder than most others. Their 1/4" connectors have small contact areas for soldering the tip and ring connections which can be a little difficult to solder at first, but are really rugged when all closed up. Neutriks require NO tools to assemble/disassemble, though a desktop vice or extra hand is a big help. If you don't specifically need to use TS connectors, you might as well cough up the little bit of extra dough and get TRS ones; when you replace an unbalanced box with a balanced one you won't need to reterminate your snake.
Wiring it up
Patch bay jacks come in many different flavors, with the most common being a vertical pair that screws into the patchbay faceplate from the rear. Some bays have individual jacks rather than pairs, and these are also generally configured as if they were paired. Vertical pairs have three standard configurations, all of which have the output over the input. This makes the signal flow "down" a patchbay, from output to input. I'll explain why that's helpful in a minute. A normalled jack pair is one in which the signal coming into the back of the top jack feeds the connectors on the back of the bottom jack until a plug is inserted into either jack of the pair. Despite the name this is not necessarily how things should be connected "normally". If you have one output of a multitrack recorder connected to the rear of the top jack, and the rear of the bottom jack connected to a line input of your console, the signal will flow from tape machine to mixer with no additional cable. Plugging into the top row will give you the output of the multitrack to send somewhere else while cutting its connection to the console. Plugging into the bottom row will allow you to feed some other source into that console channel, again cutting off the connection between tape machine and mixer. In a half-normalled jack pair the signal coming into the back of the top jack feeds the bottom jack unless a plug is inserted into the bottom jack. This allows a cable to be plugged into the top jack while the signal still flows to the bottom one, splitting the source. In our previous example the tape deck output would be both available to be patched somewhere else AND flow to the console when a cable is plugged into the top jack. A plug in the bottom jack would still disconnect the tape deck from the mixer.
If you want to patch mic jacks (from recording rooms) to mic preamps don't half normal them! You'll change the impedance that the mic is driving into (changing its sound) if you "split" the signal and plug the mic into a different mic pre. You could also drive two phantom power supplies into each other if you did this. Not good. In an un-normalled jack pair there is no connection between top and bottom jack. Many times outboard gear has its own area of the patchbay, as we don't want to normal compression or reverb into specific channels. So frequently there's a large section of a bay which consists of the inputs and outputs of the external processing gear. These are still set up output over input for consistency, but feeding the output of a processor back to it's input gives an instant feedback loop. Of course you could half-normal the jacks and then tap the feedback the processors are generating, if that's your thing. I'd suggest making sure that all processing gear is on un-normalled jacks.
So how do you know if the bay you're looking at is fully-, half- or un-normalled? Look at the jacks. Five solder points at the back of the jack indicate that you have connections for tip, ring, sleeve, tip normal, and ring normal. Three solder points are tip, ring, and sleeve. Two are tip and ring, with the chassis serving as ground, unless you've got an odd bay that can't handle three conductors (which all balanced connections need). You should be able to see from the side of the jack how the normals rest against the tip and ring connectors until a plug is inserted, at which point the tip and ring connectors are pushed away from the normals, breaking the connection. So, to wire a fully-normalled jack pair, connect top tip normal to bottom tip normal, ring normal to ring normal, and ground to ground. To make a half-normalled jack, connect top tip (signal source, not the normal connector) to bottom tip normal, top ring to bottom ring normal, and ground to ground. Doing this keeps the signal flowing top to bottom even when a jack is inserted in the top position. For an un-normalled jack, just connect grounds.
Now that I've mentioned it, the patch bay can and should serve as ground central for your audio system. Grounding is a whole other article, but try to maintain one good path to one good ground for as much of your audio system as possible. You will likely want to connect the grounds of all the jacks in the back of a bay together (using solid copper to do this makes it pretty quick work, or try extra sections of drain wire) and then connect that patchbay ground to audio ground of the console. Usually the best spot to do this is where the ground from the power supply is distributed through the console. If your gear already has a good path to ground, all you may need to do is make sure that the bay passes the ground when you make connections. Some gear uses its electrical ground as its audio ground, in which case grounding to the patchbay will likely cause ground problems unless the electrical ground and the patchbay ground have the same potential. Some quick trouble shooting will generally show the culprit and lifting the audio grounds (NOT the AC grounds) to the patchbay should clear up the problem.
