Don’t Fear the Gear, Part 2: F.I.N.D. the Problem
Learn how to effectively troubleshoot any audio system challenge.
It’s T minus 30 seconds until class begins. Your MP3 player appears to be working, but you can’t hear the music. The microphone works, but your voice is drowned out by a terrible staticky sound. Worst of all, there is a room full of people staring at you, arms impatiently crossed. “Houston, we have a problem!”
In our last installment (“Don’t Fear the Gear, Part 1: Signal Flow,” in the March issue), we discussed the pathways that audio signals take from one piece of gear to the next. It’s within this chain that many problems arise. In this article we’ll discuss how to F.I.N.D. common audio challenges and get your class back on track.
Go With the Flow
Figure 1 may look intimidating, but this basic flow chart simply demonstrates a process of elimination. One by one we’ll deduce which problems cause our audio woes. Let’s start at the beginning.
The Problem. The MP3 player appears to be working and the song is playing, yet no music is audible. According to the “Go With the Audio Flow” chart, it’s time for the kindly dubbed “idiot check” step. These tips may seem obvious, but they point to the root causes of most issues. A quick preclass run-through of these potential trouble spots saves time and fixes many problems.
First, is the power supply plugged into a wall outlet? If so, check that system lights are glowing on each piece of equipment. If one piece has no glowing lights, chances are the problem lies with that piece or its connections (more on those in a moment).
Second, ensure that the mute switch is not in the “on” position (on the microphone) or that the mute button is not depressed on the mixer. It’s a quick fix—just change it to the “off” position.
Third, look at the volume controls. Volume can be tricky because on most systems there’s more than one place to adjust it. Each component has volume controls, and the mixer has its own set. A good rule of thumb is to keep the volume level on the source piece of equipment (say, the MP3 player) at 75% of the maximum. The art of finding the best combination of levels among components is called “gain staging” and is usually a task for a professional installer. In most instances, you should keep the individual volumes set at the default levels and adjust only the master volume. Having said that, if the volume for the MP3 player channel on the mixer is turned all the way down, it’s a safe bet to turn it up. Smart facility owners mark default levels on the equipment, giving instructors an easy diagnostic tool.
Last, check all connections and cables to make sure they’re not only plugged in but also have no visible tears, splits or loose ends. If a cable is disconnected, trace the free end back to the attached component. Assess whether this disconnected cable is causing your problem, and act accordingly. Use caution, as it is possible to damage the system by interchanging the wrong cables. Be prepared to put things back the way they were. On most group fitness audio systems, the MP3 player and the microphone transmitters and receivers are the most accessible components and therefore the most likely to become unplugged.
If after the idiot check there are still no audible sounds coming from the system and power seems intermittent or not present at all, ask the maintenance department or your manager if other areas of the facility are experiencing similar power issues. Tripped breakers, power surges or even lightning strikes are all possible culprits.
Signal Sabotage: F.I.N.D. the Culprit
If the idiot check yields no results, but sound is coming from the speakers (although it might not be pretty), it’s time to go to the chart again to F.I.N.D. the cause. It’s common to hear “unintended” sounds coming from the speakers, often at an uncomfortable volume. What most people don’t realize is that the type of sound can indicate the root cause. Feedback, Interference, Noise and Distortion are the most common types of signal “sabotage.”
Feedback is familiar to anyone who has ever walked in front of a speaker while holding (or wearing) a microphone. This telltale sound is a whine, shriek or howl consisting of a single, pure tone. More often than not, it is uncomfortably loud, and participants’ immediate response is to cover their ears or run for cover. A feedback loop occurs when the sound from the speakers makes it back into the microphone and is reamplified and repeatedly sent through the speakers again (How Stuff Works 2011). The effect can be either gradual or immediate. Avoid walking in front of or pointing the microphone directly at the speakers. Strategic speaker placement helps to eliminate this problem or at least minimize how often it occurs.
If that doesn’t seem to be the issue, it’s likely that the microphone or system volume is set too high (i.e., it’s “hot”). Turn the microphone volume all the way down; this should instantly eliminate feedback. You can then gradually turn the volume back up to a comfortable level. Sometimes, however, certain frequencies have a tendency to “jump out.” If the ringing tone recurs in a particular space, it may be time to invest in a feedback eliminator. This small device takes the signal from the microphone and “cleans up” the frequencies.
Interference is a little more challenging to pinpoint and usually requires a bit of trial and error. Examples include static, clicks, digital beeps, radio or even someone else’s voice. Wireless technology has made interference more of a problem than ever before. With only so many frequency bands to go around, there’s bound to be signal confusion or “cross-talk.” If an intermittent sound like a dial tone is coming from the speakers, check that a cell phone isn’t sitting on top of the stereo system or in the near vicinity. If you use an iPhone or similar device for your classes, switch it to “airplane” mode before plugging it in.
If the offending sound is like static, the most common culprit is the receiver of a wireless microphone. With certain models you can squelch this awful sound with (you guessed it) the “squelch” setting. When you turn the squelch knob to the right, unwanted frequencies get ignored and the strongest signal (your voice) is amplified. However, if you turn the knob too far, it will eventually squelch out your microphone signal, so adjust with care!
If neither option provides a solution, change the channel assignment on the microphone. It’s possible to pick up signals from instructors teaching elsewhere in the facility or even from local radio stations. Fortunately, microphone manufacturers are now providing autoscan receivers that help with this problem.
Noise actually has many definitions, depending on the situation. For our purposes we’ll define it as “a disturbance interfering with the usual operation of a mechanical device or system.” Sticking with this logic, noise in the group exercise room often comes across as intermittent crackling, clunking or “thunks.” First look for any correlations between the suspect noise and your movements or those of participants or pieces of equipment. If you jump up and down and the noise happens to be in sync with your movements, it’s likely that the microphone is the source of the problem. Check for cracks in the microphone antenna. If the facility uses a microphone with a dangling antenna on the belt pack, double-check that the antenna is not folded, crimped or caught up in your clothes. If your microphone comes with a windscreen (foam ball), use it! This cuts down on breathing sounds and helps protect the microphone from sweat and condensation. Additionally, if your headset has a little bubble at the back for the battery, make sure you use the sweat guard that came with it. Sweat and electronics don’t mix!
Think of a guitar from a 1980s rock band when troubleshooting distortion. If a “crunchy” sound is coming from the speakers or the music is audible but just doesn’t sound quite right, signal distortion may be the issue. If you notice that the crunchiness happens more frequently at the high points of a song or when you’re talking loudly, immediately turn down the master volume and see if that does the trick. Then look at your sources (microphone, MP3 player, CD) and see if the individual volumes are set at an appropriate level. If the crunchiness sounds like “flapping” or like air passing through a torn paper bag, inspect your speakers as soon as possible. It’s quite likely that a speaker cone is “blown.” This can happen for several reasons, but the most common cause is that the volume is too high for the system’s capabilities.
If speaking into the microphone sounds more like speaking into a wet blanket, the distortion is coming from a sweat-saturated microphone. This is especially a problem at facilities that offer many back-to-back classes. For this reason it is important to swap out windscreens after each use. Gently pat the speaking end of the microphone dry with a tissue and keep spare windscreens on hand.
Trust in the Process
Let’s get back to the secondary issue—static emitting from the microphone. The idiot check is clear, but there is still a racket. You assume the microphone is the culprit since the sound happened the moment you popped a battery into the transmitter, but you need to be sure. You first turn the master volume all the way down so as not to deafen participants a second time. When you look at the microphone receiver, you see that the horizontal light meter is aglow and is peaking (red lights on the meter). The fact that the sound was very staticky in nature leads you to believe that something else is interfering with the microphone signal. Since you left your cell phone in the locker room, that can’t be it, so you give the squelch knob a small turn to the right. The light meter—although still glowing—is no longer “in the red,” so you cautiously turn up the master volume. You still hear a small amount of static, so you tweak the squelch to the right once again. This time it’s all clear! Trust in the troubleshooting process and you’ll never fear the gear.
How Stuff Works (2011). What causes that howling sound in PA systems? http://electronics.howstuffworks.com/gadgets/audio-music/question263.htm; retrieved Dec. 26, 2010.