Gary's Wireless Handbook

 

RF veteran Gary Stanfill details common - and not so common - problems that can severely impact wireless system performance.

Chapter 1: Antennas, intermod, frequencies and batteries
Chapter 2: Clear path, antenna cables & splitters, remote whips
Chapter 3: Digital interference, lav mic issues, overall sound quality
Chapter 4: Preventing and getting rid of noise
Chapter 5: “Max” wireless audio quality
Chapter 6: Antennas? Well, it is wireless!
Chapter 7: Legal use of wireless microphones
Chapter 8: Requirements for using wireless systems on TV channels
Chapter 9: Unsettled times ahead for wireless systems

Related articles:

Wireless Jungle: Pro audio weighs in on the FCC - Under consideration by the FCC are proposed new rules that would allow unlicensed equipment to operate on "unused" TV channels in competition with wireless mics. The valuable contributions of Shure, Audio Technica and Sennheiser in fighting this proposed action must be acknowledged.

The RF Picture in the U.S.:Listing of frequencies available and occupied in the top 30 U.S. metropolitan markets.

Syn-Aud-Con Tech Topics by Pat Brown. An ever-growing collection of in-depth technical articles explaining audio system problems and offering effective solutions.

Limiters Unlimited. Reign over your system’s volume, protect speakers and more with a better understanding of how limiters work and how you can use them to best effectiveness.

Measuring intelligibility. In our continuing series on we present a thorough look at how statistical measurements are taken with human beings, and what this means in terms of speech intelligibility.

Wireless problems looming? While to this point the digital television (DTV) “revolution” has been a bust in the U.S., entertainment wireless users still need to be aware of possible complications on the horizon.

Wireless bodypack antennas. What’s that long antenna do? And does it even have to be so long? How about options? Common questions on this pesky issue - answered!

Graphic system layouts. Confused about the different approaches to sound system design? Check out this handy graphic representation of the most common system configurations and a chart on the upsides/downsides of each approach.

Array low-frequency control. Array directivity control theory is not new, and several noted designers have been using sophisticated line array designs for installed sound systems for several years. But here's something new...

Speech intelligibility? The goal of most sound reinforcement systems is to deliver speaking voices with sufficient clarity. Sometimes, things go wrong. A discussion of the factors that cause problems, and more.

Series or parallel? Connecting multiple loudspeakers can be tricky business. Should you go with series or parallel. Impedance is the thing, as Pat Brown explains.

Suspending loudspeaker systems. Check out part 1 of an ongoing series that goes in-depth on what you need to know for correctly (and safely) flying speakers. Design factors, rope terminology, types of knots and more.

Microphone techniques. Here's the lowdown on how mics work, and as a result, how that influences the techniques you use to capture sound in live applications.

Understanding the time domain . Sure, you've heard of the impulse response, but how do you interpret it? Also, how to apply this information to your system. Lots of well-defined graphics.

Get wire gauge right. Appropriate wire gauge is vital to system performance. Too “light” and you waste amp power, too “heavy” can be awkward and costly, at the least. Commentary and helpful tables.

Zoning the stage. New directions in stage signal routing and management detailed. Over the past decade or so, there's been a gradual shift with the advent of stage zoning. Find out more!

Speaker Power Requirements. Get answers to many of your most-often-asked questions about sound system power. What's "peak"? How about "music power versus program power"?? Plus much more!

Smaller & lighter & digital. How small can power amplifiers get before they become ergonomically difficult to use? Jeff Kuells believes Powersoft might have found the limit. He put them on the bench and worked with them in the field.

Why not Wye? A strong case against using Wye (or “Y”) connectors in hooking up your system. The approach can compromise signals to a great degree and even result in damage of the equipment involved.

Audio power trip, part 2. The role of impedance, resistance and reactance in an audio system. Get your amplifiers and loudspeakers working together as well as possible!

Inside power amps. An in-depth primer on power amplifiers. What’s a class? How about distortion. Defining sound quality? Also, amplifier design trends.

Lobes and nulls.Equalization and other processing are no substitute for proper loudspeaker placement. A thorough discussion of getting it right the first time to prevent problems!

System & room interactions. If one could listen to only the direct sound of a loudspeaker, the world would be a very different place! But that's not the case. Sam Berkow provides a detail discussion and data.

Audio Power Trip. Few subjects generate more confusion in the audio world than power. Most of us are on a power trip - our attitude is that “more is better.” But like many subjects, there's more you should know about power than meets the eye.

Parametric Loudspeakers. A look at rather unconventional loudspeaker technology being developed to deliver more tightly focused audio. The concept of using ultrasonic sound waves and more...

Inside the Contour. At NSCA Expo 2003, Lake Technologies unveiled the Contour, a digital processor offering a radically new filtering approach and a handy wireless touchscreen interface and more. Here's a behind-the-scenes look.

Equalize the room? Well, not exactly. EQs are nifty devices but they can't change the architecture of the room. Bob McCarthy explains the confusion and details exactly what equalization can and should do.

Signal processing fundamentals. What do you want to know about crossovers? How about equalizers? Controllers? Whatever the case, Dennis Bohn takes you on a thorough discussion of the essentials of processing, how it really works, and most importantly, how it can benefit your system.

SMAART and reverb time. John Murray fields a multi-part question about measuring RT60 and frequency response in a small room using SMAART Live. He clarifies the application, backed by data he's generated.

The Amplifier To Loudspeaker Interface. Is there anything special about hooking an amplifier to a loudspeaker? Here is a brief look at some parameters that can affect the sonic performance of this important interface.

Constant-Voltage Distro. Background, explanation and how-to of constant-voltage audio distribution systems, 25-, 70.7- and 100-volt systems. The correct methods, backed up by diagrams. Dennis Bohn of Rane provides the explanation.

IEM ups and downs. Sure, in-ear monitoring is great for lowering stage volume, and when employed properly, can offer hearing protection. But there can also be downsides to IEM, as Brian Belcher explains.

Audio signals & analysis. Learn the nature of peak and average levels of music and speech along with standard methods of dealing with signal peaks and required shifts in signal operating levels!

The time domain. The acoustic measurement primer continues with a look at interpreting impulse response, and how to apply this information to your system. Lots of well-defined graphics take you through the process.

Fighting for power. Increase the actual power delivered by your amplifiers to your loudspeakers by as much as 15 percent with a simple wiring change! Dave Rat, touring dude extraordinaire, explains how and offers some perspective.

Acoustic measurement primer. In part 1 of a new series, Pat Brown provides a logical way to get "up and running" with modern sound measuring instruments. Plenty of examples and graphics are included.

Did you say rock or wock? Speech intelligibility is the first objective of every sound system providing crucial emergency paging. Jeff Rocha offers a thorough examination of this issue and looks at the role native language differences can play in further muddying the situation.

Getting gain structure right. Veteran system designer Brian Elwell of Acoustic Dimensions shares the secrets for determining how much gain is required for a system and then shows how to set gain structure the right way.

Dynamic range versus signal-to-noise. The terms dynamic range and signal-to-noise are used interchangeably, even though they mean different things. Learn the differences as well as how to put this important knowledge into practice.

Handy calculators. Simply enter your data to determine key design factors in seconds, including Constant Voltage Transform Power, dB Power & Voltage, Amp Power Required, Inverse Square Law, Line Loss and Ohm's Law/Watt's Law. Provided by Crown.

Critical distance. Get a thorough explanation of critical distance (Dc) and how it impacts mic placement. And, an easy, step-by-step primer to calculate this vital factor for improved performance.

JBL Precision Directivity. Details on JBL’s new Precision Directivity (PD) line of loudspeakers for arena, stadium and other large fixed installation applications, installed in two new arenas, including the American Airlines Center in Dallas. The line includes mid/high, mid-bass and low-frequency models.

Smaart Live for beginners. Doug Fowler's continuing series, looking at system EQ and interconnect issues, as well as taking a measurement and interpreting it.
Also: Smaart Live for beginners: Part 2
Smaart Live for beginners: Part 3

How’s it work, Gary? In this in-depth look at the new Shure P4800 digital system processor, Gary Zandstra reviews the unit’s ability to meet contractor needs in small to medium installed systems. Plus, specifications and extra input from Shure, and Gary puts the P4800 to the test in a project.

For many years, Crown has been dispensing technical and application advice with its Mic Memo newsletter series. PSW Install will be regularly presenting article selections from these valuable newsletters, kicking off with “How a cardioid mic works” and “Popless on/off switch.”

Avoiding phase cancellation. You’ve got two mics in close proximity, say on a singer/guitarist in mono. One mic for vocal, the other for guitar – and it sounds funny. Bruce Bartlett explains the likely culprit – comb filter effect – and offers solutions for avoiding it while improving sound quality.

The data game explained. Accurate product data is crucial, yet much of it can be inconsistent and subject to debate. Community has spent decades in the pursuit of acquiring meaningful data, with Dave Howden providing a detailed explanation. And, Community President Bruce Howze weighs in on the topic.

Tom Young is a veteran system designer and live sound engineer, noted for his ability to thoroughly explain sound reinforcement and acoustical techniques.
Aux fed subwoofer technique
Time is on your side

A look inside B&C Speakers. How this Italy-based company produces some of the best-sounding compression drivers in the world, used in a wide range of leading loudspeaker cabinets.

Hearing loss and pain killers. Physicians have found a possible correlation between permanent hearing loss and a commonly prescribed painkiller medication that combines hydrocodone and acetaminophen.

The Crown truck. In the summer of 2001, PSW was treated to a first-hand look at the new Crown Truck, then in development. The facility further extends the company’s pioneering mobile education efforts.

Stadium sound primer. Ron Baker of WJHW, Dallas, one of the world's leading stadium sound designers, provides a primer on design approaches and outcomes.

Live or Servo Drive. Wyle Labs utilizes subwoofers to simulate jet engine spectrum and amplitude in noise mitigation research.

Technical Papers

Shure provides a definition of critical distance, discusses its importance, and offers a handy tutorial on how to estimate critical distance. See Critical distance and microphone placement.

JBL offers a straightforward discussion of damage that can occur when using an amplifier rated at less power with a loudspeaker. Guidelines are included. See Danger: Low power. (PDF Format)

Marty McCann of Peavey explains how to eliminate low-frequency noise cancellation with proper subwoofer placement. See boundary cancellation.

All AES Standards in print are now available for download at no cost. To access these documents, go to http://www.aes.org, click on "Standards" then "Standards in Print." Thanks to Jim Brown, Ray Rayburn and Bruce Olson for their work in making these docs available to all.