The EM Poll

Starting Over

Jul 1, 2007 12:00 PM, By Nick Peck

           

Cables and Patch Bays

Though it may be considered a trifle mundane in some circles, the humble patch bay is the nerve center of your studio. Careful thought should be given to layout and your approach to wiring. When done right, patch bays are intuitive, reliable, and capable of withstanding changes in layout. When not planned out, they can become sprawling, inflexible monsters.

Patch bays come in various formats. My favorite type is a 1U bay that uses Tiny Telephone (TT) jacks, offering 96 points of balanced connectivity. Each pair of patch points can be individually removed from the patch bay for soldering at a workbench if required.

The rear of the bay comes in a number of configurations. Some terminate in solder lugs, which you would attach directly to your gear with cabling. Others terminate in EDAC, ELCO, or DB25 connections, which allow you to connect large, multipin snakes directly to certain mixing consoles and recorders. Still others terminate in solderless punch-down blocks, allowing you to connect individual audio cables without having to solder the ends to the patch points. Lastly, some bays separate the patch rows from the equipment connection terminals by using snakes to connect between them.

New patch bays are great, but there are bargains to be found in used ones. I bought my patch bays in an electronics surplus store for $20 each. You can also hunt for quality used bays on eBay or through Internet vendors such as Mr. Patchbay (http://home.flash.net/~motodata/patchbays/).

The key to a successful patch bay is planning everything out on paper before you touch a single wire. Make a list of every piece of equipment you have, noting the number and type of analog inputs and outputs. Group your items by function, utilizing normaling wherever appropriate to minimize the number of patch cables needed for your default work flow.

Once you've listed all your gear, make a diagram on graph paper or in a spreadsheet of your proposed patch bay layout. That will help you determine how many patch bays you need to do it right. Be sure to leave about 25 percent of the patch bays open for future expansion — you'll be glad you did when that next piece of kit comes along.

The next step is determining where your patch bays will be located. It is a critical decision because all your cable runs will be determined by this choice. I placed mine in a rack on top of all my outboard gear. This meant short runs to individual signal processors, but longer runs to my mixer and recorders. Snakes are perfect for multitrack and mixer connections, as they allow for a larger number of connections within a smaller package than individual cables.

You will need to decide whether you will be opting for custom-length cables or not. I can't stand wading through pools of extra cabling, so I cut each cable to size. I had Redco Audio (www.redco.com) custom build DB25-to-XLR snakes for me, and I soldered the rest of the cables myself.

If you choose to solder cables yourself, be sure to use a quality soldering iron and cable jacks. Heat-shrink tubing, a good continuity tester, and a bit of patience are a must. The results will be reliable connections that will last a long time.

If you plan to make custom-length cables yourself, the next step is to take a full cable inventory. Lay them out in piles on the floor so you can easily see the ends and cable types. This is also a great opportunity to throw out those mounds of cheap, junky, or broken cables.

Measure the distance from a piece of gear to your patch bay, adding about 18 inches or so for slack. Try to find a cable that has the appropriate ends and is as close as possible to the length you need. Resist the temptation to stretch cables that are too short. For patch bay work, steer clear of cables that are thick, because they will take up too much room when clustered with dozens of others.

Once you find your cable, cut it to length and be sure to save any good-quality jacks that are on the cable end you are not planning to use. If you are soldering the cable to the patch point, remove that point from the rack and attach the cable at your workbench. Be sure to use heat-shrink tubing on the cable ends to minimize the possibility of short circuits between cables within such a tight space.

My equipment inventory and layout requirements resulted in a need for three 96-point patch bays. One is used for recorder inputs and effects sends and returns, while another is used for recorder outputs and mixer inputs, as well as group sends and miscellany. The third is dedicated to signal processing.

FIG. 3: Try to avoid running cables through areas of foot traffic whenever possible. When it’s unavoidable, minimize the exposed cabling area and arrange the cables in flat, tightly bundled groups.

The patch bays live in a 10U rack of their own, in order to leave plenty of room for cabling, and each patch bay is separated by 1U of empty space. All the cabling routed to a single patch bay runs through loops of cable ties attached to the wall of the rack. This provides strain relief for the cable connections and keeps the cabling organized.

Cable positioning always seems to be a hassle. Rule number 1 is to avoid running cables through foot traffic areas. In the past, I've built simple cable troughs out of ABS drainpipe cut in half and attached to the walls. My previous studio had cable troughs built into the foundation under the floor.

Putting a cable run behind equipment and furniture is not a problem, but occasionally you will need to run cables through an area of foot traffic. Depending on your tolerance for ugliness, you can run cables up over doorways, or through loops made from cable ties hung from the ceiling. If that is not an option, you may have to run cables across the floor. The best you can do is to minimize the number of cables by using snakes. Make sure the cables are tight and flat on the floor, using cable ties to bundle them together in a manner that won't cause a tripping hazard (see Fig. 3). You can also build a small ramp out of plywood that covers the cables, protecting them from damage.

Read more of this article on redesigning your personal recording studio