There’s no question about it: the digital age is upon us. Most students would probably laugh—or be confused—if you asked them whether they used the library’s card catalog to complete a research project, and it’s become rare to see someone pull out a map when navigating a new city. With the days of cassette tapes and handwritten phone books behind us, the audio industry has been no exception to the digital movement…and there’s no turning back.

Although you—as a retailer—aren’t required to know the history of wireless microphone system innovation, it is important that you know how to field customer questions about the advantages and important considerations when choosing which digital wireless system is the best fit for the customer’s application.

To ensure you’re equipped with the facts that you’ll need to answer a customer who asks, “Why digital wireless?”, I’ll focus first on the three key advantages to keep in mind when considering or explaining the benefits of digital wireless. I’ll wrap things up by outlining a few questions to keep in mind when shopping for the right digital wireless system.

The Three Key Advantages

Perhaps a better title for this piece would have been “Why Not Digital Wireless?”, because there are very clear advantages to choosing digital over analog, relative to sound quality, battery life and spectral efficiency.

Sound Quality: To most customers, this will be the most important factor when it comes to their purchasing decision. If they’re unsure about whether to choose a digital or an analog system, be sure to point out that digital wireless systems offer highly transparent audio quality. This is largely due to the fact that digital systems don’t require a “compander” (contraction of the words “compressor” and “expander”), which is a circuit used in all analog wireless microphone systems to minimize noise and maximize dynamic range. The audio signal is compressed in the transmitter to accommodate the limited dynamic range of FM radio and then expanded in the receiver. This process, while relatively unnoticeable in most good analog systems, still can lead to audible artifacts (like “pumping” and “breathing”) that make a wireless microphone sound different from its wired equivalent. Since the transmission of a digital audio signal doesn’t require companding, the received signal retains the exact characteristics of the original audio input.

A digital wireless system can also achieve flat frequency response across the entire audible range (20Hz to 20,000Hz), which yields the truest possible sound transmission. The microphone element (not the “wireless” components) more closely defines the frequency response of the system. Digital wireless systems convert analog audio to a digital signal that modulates a radio carrier in discrete steps, which can be thought of as a series of ones and zeroes. The digital audio signal arrives at the receiver unaffected by the radio link. Therefore, any RF noise that might be present below a certain threshold doesn’t affect the audio quality. The receiver simply ignores anything that isn’t a zero or a one. Everything else is discarded. Only the digital signal is sent on for amplification.

Extended Battery Life: In general, digital wireless microphone systems have 30 to 40 percent longer battery life than equivalent analog systems do. For example, Shure’s digital ULX-D transmitters run up to 11 hours on two AA alkaline batteries and more than 12 hours with the Shure SB900 lithium-ion rechargeable battery.

Improved Spectral Efficiency: Although this isn’t necessarily true of all digital wireless systems, the modulation type chosen by the manufacturer can potentially lead to increased channel counts in reduced clear spectrum. The deviation of a digital wireless signal is more predictable than that of a frequency-modulated analog signal, allowing tighter channel-to-channel frequency spacing. This feature is particularly important in light of the continued crowding of the UHF television band, where many wireless microphones operate. Depending on the manufacturer and the model, digital systems can often deliver nearly twice the channels in the same slice of spectrum as their analog cousins can.

Things To Consider

Whether you’re looking to carry a new line of digital wireless systems or you’re speaking with a customer who is in the market for one, it’s all about having—or setting—realistic expectations. Before making the move to digital wireless, it’s important to consider budget and latency.

Budget: For most of us, budget is always going to be an important factor when it comes to any purchasing decision. You can expect to pay about 10 to 20 percent more for a digital wireless system than you would for an analog system. However, it’s critical to retain a “cost of quality” perspective when you’re evaluating your options, because digital systems will likely offer features that aren’t possible with analog systems. These include smart battery technology, extended runtimes and more on-air frequencies. Depending on your needs and the system you choose, encryption and interference avoidance might also be features in which to consider investing.

Latency: Latency is the amount of time it takes for a signal to arrive at the output after entering the input of a digital device. In analog equipment, latency is not a factor; however, in digital equipment, the incoming analog audio signal must be converted to a digital signal. The signal is then processed and converted back to analog. Although large latency values could potentially be problematic, most high-quality digital systems produce less than five milliseconds (that is five thousandths of a second) of latency. That’s acceptable to most listeners.

Advice For Choosing The Right Digital Wireless System

There are many considerations to keep in mind when buying a digital wireless system, just as there are when choosing an analog system. Always consider the reputation of the manufacturer. Most of the major pro audio manufacturers offer digital wireless systems, but it’s important to choose one that’s known for quality, performance, reliability and customer service.

To follow are some questions that go beyond initial budget considerations to help you narrow the field, whether you’re looking for your store or whether you’re helping a customer find the right fit for his or her needs:

How many compatible systems do you need? In most cases, a school using a system in a multipurpose room, a small church needing a handful of systems or a solo artist can be served by the most affordable options.

Where will you be using it? If the digital system will be used in an auditorium, in a mid-sized venue like a house of worship with a praise band or in a rental rig for touring artists, you’ll be looking for a higher number of compatible channels and a fuller feature set.

Inside or outside the U.S.? A 2.4GHz system will work anywhere. All other wireless microphone spectrum is allocated differently around the world. [Editor’s Note: Keep an eye on the latest FCC machinations relative to spectrum auctions and available space.] So, precise selection of frequency bands is important. Frequency coordination is a requirement no matter where you operate your wireless gear. That includes adhering to local laws.
Analog audio has been a longstanding part of the audio landscape for more than a century, but digital, in just 40 or so years, has become an increasingly dominant force in the industry. “Which is better?” questions are bound to drive conversations for years to come, as users will likely deploy both technologies in an attempt to meet the varying needs of their productions. These decisions are shaped by three critical parameters of wireless microphone system performance: signal reliability, spectral efficiency and audio quality. For system-specific questions that might come up, always contact the manufacturer.

Gino Sigismondi is Senior Manager, Systems Support, at Shure Inc.

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