The Basics of Patchbays

If you're tired of climbing behind your racks, and finding the right cable every time you want to use a piece of outboard gear or a console insert point, it may be time to find yourself a patchbay. A patchbay is a central audio connection area for all the gear in a studio that allows any connection to or from equipment to be made in one location with a standardized cable and connector. Patchbays not only save time and headaches, they allow you to easily perform a number of mix tricks that would take serious head-scratching otherwise.

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.

How It Looks

A typical large scenario, involving seven rows of 24 jack pairs, with signal flow going down the bay:

Top Row: Mic Jacks 1-24 in recording rooms fully normalled to -----------> Bottom Row: Mic Preamps 1-24 in console

Top Row: Console bus 1-24 outputs half-normalled to -----------> Bottom Row: Tape Inputs 1-24

Top Row: Tape Outputs 1-24 half-normalled to -----------> Bottom Row: Console Line Inputs 1-24

Top Row: Channel Insert Sends 1-24 half-normalled to -----------> Bottom Row: Channel Insert returns 1-24

Top Row: Mix Outputs, 2 track Outs, Aux Sends, FX outputs half-normalled to -----------> Bottom Row: 2 Track Inputs, 2 track Returns, FX inputs, Aux Returns

Top Row: Extra FX outputs 1-24 unnormalled ----------- Bottom Row: FX inputs 1-24

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.

Some studio folks are less intimate with their soldering iron than others, so here are a few words of wisdom regarding "wire glue." Solder connections should always be shiny. Dirty irons, and bad habits cause poor connections! Be neat and tidy, heatshrink drain (ground/shield) wires if they'll be exposed, and try not to burn the insulation off adjacent wires when working. Heat the parts to be connected, then apply solder until it flows and connects the parts. Remove the iron promptly! For patchbays, if you're right handed, start soldering your connections at the bottom left of the back of the patchbay and move across the bottom row, then do the row above, left to right. If you're a lefty, start on the lower right. This will keep your iron moving away from the wires you've already connected. By the way, before you go wiring anything to a patchbay, make sure your console, and its phantom power supply, is off. A good stiff +48vdc phantom supply can surprise you when you least expect it.

Becoming a power user

Think: Be aware of what's connected where. I toasted a ribbon mic once when I too speedily cleared my patchbay after a session. The mic had been patched to an external mic pre, but when I unpatched it, it was then normalled to a console mic pre that had phantom power active. Oops! Also, beware of having multiple devices on the mix bus outputs. If your console mults the mix bus to multiple 2-track recorders, at least make sure they're all powered up when mixing or, better yet, disconnect the recorders you won't be using. Your console's output amps will thank you.

Extra Buses: Aux sends can also be normalled to aux returns. This gives you a few more buses at mix time if you have some unused sends and returns. Set up a tom/overhead submix on a couple of aux sends and use a stereo return to bring in the blend for fills and accents. You can solo the return to hear the submix on its own. If you use pre-fader aux sends, your aux return mix can be totally different than what's going through the faders to the mix. You can also patch your aux sends to unused input channels and EQ your submix, just don't route those channels to the aux sends that are generating the submix or you'll enter feedback city.

Mults: Mults provide "mult"iple outputs from one input. They're equivalent to a Y-cable (which, by the way, should NEVER be used to sum two or more devices together as you'll be essentially driving two outputs into each other). To make a mult on a patchbay, simply connect the signal contacts of three or four jacks together. Use a long piece of tinned wire and connect the solder tabs on the back of the first jack to the same tabs on the next jack and so on. You can ignore the normals for this purpose. Once you have the number of jacks you want connected together, cut off the excess wire. A TRS mult will require three of these short bus wires. Try multing the same sound to different faders for different sections of a song. It's perfect for the song where the drummer alternates between the snare rim and the head because you can EQ and effect each sound separately, and ride or automate mutes to change back and forth. Multing is also good for creative sound work. Mult an electric guitar and bring it up on two channels, EQ one normally, and one radically and blend to taste, then pan for an even bigger sound.

Company Where Phone What ADC: www.Belden.com 800.235.3361 Raw cable Brasso: hardware store Brass cleaner CAIG: www.Mogami.com Raw cable, Patch cables Monster Cable: www.SwitchCraft.com Patchbays, Raw cable, Patch cables Whirlwind: www.WhirlwindUSA.com 888.733.4396 Raw Cable, Custom cables, Interfaces

Inserts: I just don't use my inserts. If I need to process a particular channel, I almost always do it between the tape deck and the line inputs. The only time I use the inserts is when I need to process post channel EQ. You can decide for yourself whether you need to run your inserts out to your patchbay, just remember that you're running your signal through an unnecessary extra connector, wiring, solder connections, normal contacts on two jacks, more solder and then more wire and another connector before it gets back to where it started. I've gone so far as to connect the insert sends and returns of some channels directly to each other right on the channel cards to remove the extraneous trip to and from the patchbay. If you have master insert sends you might want to think about finding a way to bypass them if you never use them. When I had a MCI console someone had modified the board with a pre-fader master insert send which went through a driver amp, an unknown output transformer, to the patchbay, though normals, back through another mystery input transformer and then to the fader for a net loss of 6 dB. I pulled the whole rig and was much happier with the sound of the console and never missed the insert point. Normally one might use the pre-fader inserts so that master fader moves (like fades) don't affect threshold settings on dynamics processors on the mix bus. I leave head and tail fades for mastering anyway (an analog console can only fade to or from its noise floor and not digital black, so when you fade out on an analog console you reduce your signal to noise ratio), so having a pre-fader insert on the mix bus is not imperative for my needs. I simply patch whatever stereo processing I need between the mix outputs and the two-track inputs.

Cabling: Numbered cables and a standardized numbering scheme are good. Given a 24 pair snake, I always know which pairs are inputs and which are outputs. At the equipment end, I number as follows: #1, Processor A, Input Ch 1; #2, Processor A, Input Ch 2; #3, Processor A, Output Ch 1; #4, Processor A, Output Ch 2; #5, Processor B, Input Ch 1, etc. This is based on the most common rear panel layout of my outboard gear and results in the cables reading 1-4 left to right when I lean over the top of my rack and look at the backs of the processors. From behind the rack it reads 4-1 left to right, but I normally am working from the front, even when swapping out gear, and only go behind for major rack surgery.

Multi Pin connectors: Using Elco/Edac or other multipin connectors (available from Markertek, DigiKey, etc.) on the back side of the patchbays can make quick configuration changes possible. If you go back and forth between different multitrack decks but only have enough line inputs for one deck, a multipin connector can make the switch with one connection. A 90 pin Elco connector is ideal for connecting 24 balanced lines, with some points to spare.

The odd piece: You're bound to run into the extra piece of gear that shows up with a client or friend for a day or two and then goes away. My solution is to wire a number of Neutrik combo connectors to some spare points in the patchbay. The combos accept male XLR or male 1/4" TRS connectors, so adding a mic in the control room or another synth or processor is easy, and having the signals show up in the patchbay means you can freely send them to any of your gear without any fuss. Markertek sells eight of the combo connectors mounted on a single space panel for about $70. Solder 'em up and you're good to go. What's even cooler is the solder connectors for the two plug styles come out independently on the back of the jack, so you can have the XLR on one jack feed a mic pre, and the TRS on the same jack feed a line input, if you so desire.

Polarity reverse ("phase"): My console has a polarity switch on the mic pre, but not the line input, and occasionally I need to flip polarity on a track coming off tape. The solution? On an unnormalled jack pair connect the tip connector of one jack to the ring of the other, and the ring of the first jack to the tip of the second. Connect the grounds and you've got a "phase" reverse jack pair.

Cleaning: If you don't have to mount your bay horizontally, don't. A vertical bay will stay much cleaner as dust wont tend to settle into the empty sockets. The occasional noisy connection can usually be cleaned up just by rotating a patch cable in the jack. Tough problems may call for a quick coat of CAIG DeOxit on a plug and then a couple twist and clean cycles. Worst case scenarios call for a burnisher, a plug sized file that grinds the metal contacts when inserted into a jack and turned. Use burnishers carefully, they REMOVE metal that you can't get back.

Though it takes some mental and physical work to get a patchbay pulled together, once you do you'll wonder how you ever did without. Speed, flexibility and organization all increase with a well though out patchbay installation, and people always seem to love to see an engineer plugging madly away.