The Show Must Go On

Pat Kirtley shows you how to develop the logical troubleshooting skills necessary to help you quickly diagnose the sources of onstage equipment failures
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Trouble, as the lyrics of almost any blues tune will tell you, is a part of life. If you're a performing musician, trouble can take the form of equipment failure that can ruin a show. In an ideal world, all musicians would have an expert tech staff to repair and maintain their gear, but the reality is quite different. Most bands and solo performers, especially during the up-and-coming phase of their career, have to deal with on-the-gig gear troubles themselves. You either get tossed around by fate, or you learn how to face ol' man trouble head-on.

But if the idea of solving onstage equipment trouble conjures up images of complex test equipment and big red Craftsman tool chests, rest easy. Your best problem-solving tool is your brain, and in this article I'll show you how to develop the logical troubleshooting skills necessary to help you quickly diagnose the sources of onstage equipment failures. I'll also describe preventive maintenance measures you can take and offer suggestions for developing contingency plans for working around major gear failure during a performance.

RULE #1 KEEP YOUR COOL WHEN PROBLEMS ARISE

Panic is a common reaction among performers who are faced with equipment failure just before or during a show. Under the grip of panic, time compresses, feet and hands move more slowly, and brain function stumbles to a halt. Performers who panic haven't developed the most essential skill for dealing with equipment emergencies: keeping a cool head. Staying calm, even to the point of seeing the humor in a situation, is a great ability to develop. Getting upset and assigning blame during these crucial moments is just a waste of time. The best approach is to think, “What can I do, right now, to get us back on track?” Your actions will make a difference, if you're the coolheaded one.

It's easier to keep your cool if you've learned to expect random failures and prepare for the worst each time you head out for a gig. Murphy's Law — “anything that can go wrong will go wrong” — is revisited every day, whenever technology is involved. Any expert in live audio can tell you that gear failures are a part of life. Stage techs routinely spend a portion of each working day tracking down and correcting problems. Big venues with full-time engineers are great, but most bands and performers play in a variety of places, many of which don't have a house system. At those times, it's your gig and your equipment, with no audio experts waiting in the wings to help.

RULE #2 DON'T IGNORE THE OBVIOUS

When you get no sound from your mic or instrument, the first thing you should do, before going into any serious troubleshooting routines, is to check the obvious possibilities. Is your volume turned up? Is your cable fully plugged in? Is the switch on the mic turned on? Has the mixer been accidentally left in solo mode or with a channel muted? It's amazing how many problems are the result of “little things” like that and can be easily rectified. Once you've ruled out the obvious, however, it's time to move on to more serious troubleshooting.

RULE #3 CHECK YOUR SIGNAL PATH SYSTEMATICALLY

In order to quickly diagnose gear troubles, you need to use the technique of logical troubleshooting. It allows you to systematically figure out the source of a problem and helps you avoid the wild-goose chases that can occur when you randomly start swapping out cables and components in the hope of making a quick fix.

The idea is to troubleshoot electronic systems using the concept of directional flow. Like the water in rivers and streams, audio signals pass through each electronics unit or cable in a specific direction. Having a mental picture of the signal flow allows you to know what to expect at each point along the way. (For reference, you might even want to draw a diagram of your setup, clearly showing its components and signal flow, and carry it with you.) Working backward from the output to the input of a sound system, you learn to divide the signal path into easily understood sections and to check each section as you go.

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FIG. 1: This step-by-step diagram illustrates one approach to logical troubleshooting. The problem in a malfunctioning P.A. is isolated by working backwards from the output.

Here's a hypothetical example. Let's say you have a P.A. that includes a mixer with a mono output feeding a ⅓-octave equalizer. The output of the equalizer is patched into your power amp (which is configured for mono operation) and that feeds the main speaker pair. Here's the problem: you turn on your system at sound check, and when you test your mics, no sound comes out of the main speakers. After glancing at your power indicators to make sure that everything's turned on, ensuring that your components are set correctly, and checking that your cables are properly connected, take the following steps (see Fig. 1). First, connect a signal source (a portable CD player works well for this application) directly to the power amp, thus bypassing everything before it in the chain (the mixer, the equalizer, and the connecting cables). If you hear clear audio from the speakers, you can logically rule out everything from the amp to the speakers as the source of the problem.

Next, reconnect the equalizer's output to the power amp's input and patch your test signal into the equalizer's input. If you still hear clear audio, then you know that everything is okay between the equalizer and the power amp. You can therefore deduce that the problem is with either the mixer (again, make sure its controls are set correctly) or, more likely, with the cable between the mixer and the equalizer. For the sake of this example, we'll assume the cable is the culprit and that swapping that cable with a new one solves the problem.

Admittedly, the above is a simple example, but the step-by-step logic is always consistent. The same technique — working from the output end of the system back toward the input — works for tracking down no signal, weak signal, or distortion, and can be used on instrument rigs as well. (Some technicians troubleshoot from input to output, and some even start in the middle. However, I recommend the output-to-input method because it's simple and easier to understand.)

RULE #4 ROUTINELY INSPECT YOUR GEAR FOR TROUBLE SIGNS

Sometimes big trouble starts small. A loose screw in a microphone housing finally falls out and gets lost. The output jack on a hollow-body guitar loosens, and before you know it, the nut falls off and gets lost, and the jack drops down inside the guitar. A cable looks frayed at the point where it meets the connector. One day it will come apart. Will it happen during a show? By keeping an eye out for the small clues, you can take action early on instead of reacting in horror when it happens just before — or during — your big gig.

Develop a routine of checking over cables, musical instruments, pedals, mics, and rack gear on a regular basis. In bands, everyone can check his or her own gear. The things you look for are usually obvious — loose screws, damaged cables, connectors that don't fit the way they should, and anything that only works intermittently. It's amazing how much more reliably everything seems to function when each little problem gets attention before it becomes a big one.

Preventive maintenance, as it's called in the industrial world, is always easier and less expensive than repairing or replacing equipment. Although some musicians may disdain the idea of becoming mechanics or electro-geeks, one can feel a sense of pride in the simple act of tightening loose fittings, properly coiling and storing cables at the end of the show, or inspecting the back of an equipment rack in search of wiring problems.

Pat Kirtleyis a guitarist, composer, and recording artist with an extensive background in pro audio. His newest CD release is titled Brazilian Guitar. Thanks to Emile Menasché and Allen lam for their assistance.

RULE #5 DON'T LET INADEQUATE AC LEAVE YOU POWERLESS

Stage equipment is totally dependent on a source of constant, reliable AC power. Unless you play exclusively in one venue, every new show offers the possibility of AC power problems, including overloads, grounding problems, and audio interference.

You can help prevent overloaded circuits by knowing in advance how much power your equipment draws. Here's an easy way to do it. Make a list of all the electronic gear that your band uses (see the sidebar “Calculate Your Power Needs”), including lights if you have them. Then look at the back panel of each unit, and write down its AC wattage rating. (Don't get these power consumption ratings confused with power output — for a given piece of equipment, the two are rarely the same.) Next, convert the wattage ratings to amperage ratings, since that's the way AC circuits in buildings are rated. (On some gear, especially the pro-audio variety, the power consumption rating is already expressed in amperes.) The conversion takes a little math, but it's easy. Divide watts by 120 (in the United States, the standard line voltage is 120 V) to get the rating in amperes. Now, add up all the amperage ratings to get the total AC load requirement for your band. This is a conservative figure. The total (peak) current isn't reached unless you are at maximum volume level with the lighting system at full brilliance; the average load is considerably less.

With your power numbers in hand, you can now take a more intelligent approach to setting up in any venue. Many wall-outlet circuits are fed by a 20-amp circuit breaker. If you exceed 20 amps of current at the outlet, even for a short time, the breaker will trip. A good strategy to use to avoid overloads is to find outlets served by separate circuits and divide the equipment load between them. The most obvious split is to connect audio and lighting gear to separate circuits.

Try to find “clean” circuits that have no load on them (for example, refrigeration units or miscellaneous lighting) other than yours. Having a dedicated AC access also helps avoid audio interference problems caused by things such as compressor motors starting and stopping.

Another important AC supply factor is the cabling you use to get from the wall socket to your equipment. Since there are so many individual power cords for all of the units on the stage, it is necessary to combine them into just a few lines going to the power outlets. The best way to do that is to use heavy-duty power outlet boxes, which can be either purchased from an electrical distributor or made up by an electrician. Avoid department store extension cords, even if they are the rugged-looking “outdoor service” variety. Most of them have cable conductors too small to deliver sufficient current to band equipment, especially at lengths approaching 50 feet, the maximum length typically required at venues. When it comes to AC power distribution, get the good stuff and you'll never look back.

RULE #6 MAKE CONTINGENCY PLANS

Even after you've learned to be cool and logical in tracking down sound-system problems and you've taken preventive measures, you can still be slammed by something much worse than a bad cable or flaky connection. When major problems, such as the failure of a critical piece of gear, occur just before show time, solving the problem becomes a matter of survival. The secret is to work out, in advance, specific actions for specific failures. It's a creative game you can play during off hours. Start by playing “what if?” with your current roster of equipment to determine ways to go on with the show.

It's a good idea to develop quick-response contingency plans for all the possible failures that might occur. Do you know how to switch the P.A. over from a triamp to a biamp configuration if a power amp should fail? If your instrument amp dies, do you have a preamp that you can use to plug directly in to the P.A.? Do you know where all the fuses are in your equipment and how to get to them during a show? Do you remember where you keep the spare fuses? Do you know how to properly mic an acoustic guitar in case its internal pickup system goes out during the show?

These are things that allow you to keep the show rolling even though failures occur. Just think, “What can go wrong?” and develop creative ways to deal with each possible disaster scenario. Besides coming up with ideas for work-arounds, this is also a good time to write down a list of possible spare items to carry with you (see the sidebar “A Musician's Survival Kit”). Fuses, batteries, special cables, vacuum tubes, adapters, and field-replaceable speaker drivers are possible life-saving items, and you are unlikely to find them nearby at 8 p.m. on the evening of the gig.

With gear that contains programmable processors, including keyboards, MIDI controllers, lighting controllers, and some effects processors, losing a patch or program can mean the loss of a critical sound element or effect capability. Although most units don't lose user programming when disconnected, it's fairly easy for someone to overwrite your settings accidentally. Find a way to reestablish your important programs. Many units have a System Exclusive (SysEx) function that allows you to save the programs on a notebook computer. Finding out how to back up the unit is worth it for the peace of mind you gain.

RULE #7 NO MATTER WHAT — THE SHOW MUST GO ON!

I recently attended a concert of a group that I like. Everything was going great until just before the last number, when all power to the stage failed — lights, sound, everything. Instead of saying “Oh well, good night everyone,” the band moved to the edge of the stage and played the last tune acoustically. In the dimly lit auditorium, the audience of 1,200 held its breath as the group performed its most memorable song of the evening. The crowd response was deafening, and no one there will ever forget how effectively those guys handled the worst failure you could imagine. You got the impression that they'd gone through that before and had a plan.

Performing live can be a totally thrilling experience, if the technology works the way it is supposed to. There will also be moments when things break down and refuse to function. By developing the winning combination of coolheaded common sense, preparedness, prevention, and a disaster response plan, you'll have the satisfaction of knowing that no matter what comes your way, the show will go on!

Advice from the Cable Guy

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FIG. A: Proper cable-wrapping technique will help prevent future breakage.

When equipment fails onstage, faulty cables are often the culprit. Proper handling can help minimize cable breakage.

When storing cables, treat them with care. Do as the professionals do and coil the cable into a loose circle. Starting with the cable flat on the floor, hold one end in your left hand, and then use your right hand to loop the cable into a circle roughly 15 to 18 inches in diameter (see Fig. A). As you wind the loop, gently twist the cable clockwise with the fingers of your right hand, and it will smoothly curve into place. If you store the resulting circle of cable flat (with velcro cable ties to keep it together, if desired), it will be kink-free and flexible each time you use it.

Replace cables (or have them repaired) if they show breaks or looseness at connector attachment points, if there is visible damage anywhere on the surface of the cable, or if a cable exhibits intermittent operation at any time.

Label that cable! Many cables look similar but don't work the same way. For instance some speaker cables, with ¼-inch plugs on each end, look like instrument cables. Confusing the two will cause significant trouble. Avoid the problem by making small labels and taping them on with strong, clear tape. Commercial label solutions are also available.

Tips for Trouble-Free Gigging

  • Don't blow things up! Hooking up amps and speakers correctly is critical. It's the one area of audio in which significant amounts of power are transferred. If you hook up a mic incorrectly, about the worst that can happen is that it won't work well. But if you err in connecting speakers to amplifiers, the resulting smoke may signal serious, costly equipment damage. Always check the amplifier's instruction manual when hooking up unusual speaker loads.
  • Once you have your equipment setup dialed in, write it down! You can make simple connection diagrams for the P.A. system, instrument amps, and keyboard setups, including all cable routing and the basic settings of knobs, switches, and faders. If anything is accidentally changed between gigs, you have a reference point from which to proceed. That can save critical time before a show.
  • Lighting equipment that uses dimmers has a bad reputation for causing noise and buzzing in audio gear. If you can, power the lights from an AC circuit that is separate from the one you're using for the audio gear.
  • Do not cut off, bypass, or disable the ground prong on AC power cables. When present, the ground prong performs the function of isolating human beings from dangerous voltages when certain types of internal equipment malfunctions occur.
  • Create an equipment checklist to be used prior to loading out for the gig so that you can avoid leaving some critical widget behind. Also, make photocopies of important sections of instruction manuals for all equipment, and put all this information in a three-ring binder with index tabs for quick access.
  • Keep audio cables separated from AC power wires and transformers. Power cables, motors, and transformers generate magnetic fields, which can induce hum in nearby audio cables. Keep audio cables at least half a meter away from power cables. If the audio cables must cross a power cable, they should do so at a 90-degree angle to minimize hum pickup.
  • If you must use AC power extension cords, make sure they have the proper rating. The ubiquitous 6-outlet switched “power strip” should be used only for devices with small power requirements (rack effects units, keyboards, CD players, and so on) and must be used with care to avoid overloads. The maximum rating for many small power strips is only 10 amps (and that doesn't mean 10 guitar amps!).
  • Arriving early at the venue is essential; it gives you time to familiarize yourself with the layout and scope out the best stage setup for your equipment. If the setup and sound check go smoothly, small problems are less likely to become gig-threatening experiences.
  • Reduce the possibility of turn-on transients damaging speakers by applying power to mixers, processors, and effects units first; turn on power amps as the very last step. Reverse the sequence when powering down.

Calculate Your Power Needs

Make a list of all your gear and include the power consumption rating for each piece. Convert watts to amperes and then add those figures up to calculate the total amount of power your band needs.

Audio equipment Watts Amps

crown 2 × 800W amp 1,600 13.3 Crown 2 × 800W amp 1,600 13.3 Mackie 24 ch. mixer 200 1.7 Lexicon efx. unit mpx. 100 50 0.4 Alesis multiband eq. 50 0.4 Alesis multiband eq. 50 0.4 Alesis compressor 30 0.3 Rane active x-over unit 80 0.7 Furman rack lighting 100 0.8 Shure wireless receiver 30 0.3 Marshall amp 750 6.3 Fender twin amp 400 3.3 Hartke bass amp 800 6.7 Line 6 pod pro rack 50 0.4 Pedal board supply 40 0.3 Korg Triton kybd. 150 1.3 keyboard mixer 80 0.7 Roland kybd. 125 1.0 Kybd efx rack 180 1.5 Total load current for audio 53.0

Lighting equipment Watts Amps

Par cans (10 × 150W) 1,500 12.5 Long throw floods (2 × 1,000W) 2,000 16.7 Strobe 200 1.7 Dichroic efx. lights (2 × 400W) 800 6.7 Total load current for lighting 37.5

A Musician's Survival Kit

Needle-nose pliers
Standard Phillips screwdriver
Standard flat-blade screwdriver
Miniature screwdriver set
Allen wrench set
Nut driver for tightening loose ¼" jacks
Truss-rod adjusting wrenches for guitars and basses
Utility scissors
Pocket knife
Flashlight
Extra fuses of each type used in equipment collection
Replacement vacuum tubes of each type used in tube equipment
Simple voltage test light to confirm presence of AC power
Cable tester
AC line voltage monitor meter to ensure that line voltage is proper and steady
Various audio adapters (¼" to XLR, RCA to ¼", and the like)
Brand-new cables (mic, instrument, speaker, and MIDI) held back for emergency use only
DI boxes with ground-lift capability
Extra batteries of each type in use
Extra bridge pins for acoustic guitars
Extra strings, drumsticks, and drum heads
Extra all-purpose mic