Navigating the Squeeze

Not too long ago, Pro AV and broadcast equipment occupied two separate worlds, defined by very different production goals and budgets. Today, those separate worlds are merging into one.

This convergence is dramatically reshaping the expectations surrounding wireless microphone deployments. Whether outfitting a corporate boardroom, university lecture hall, or major league sports stadium, end users now demand broadcast-tier reliability from all of their wireless mics.

Mark Donovan, director of commercial applications at Audio-Technica U.S., noted that wireless microphones have transitioned from being event-driven tools to becoming core infrastructure in installed AV systems. "Corporate, education, and government environments now expect wireless audio to perform with the same consistency as networked systems," he said.

Unfortunately, delivering pristine, uninterrupted audio via wireless is becoming exponentially more difficult. As the demand for wireless connectivity in Pro AV spaces skyrockets, the spectrum it uses is becoming more crowded. Navigating this increasingly congested RF environment requires a deep understanding of new transmission technologies, rigorous security protocols, spectrum policy, and strict deployment best practices.

More with Less

The most pressing trend affecting the state of wireless microphones today is the severe congestion within licensed frequency bands. The available real estate for wireless audio is disappearing, putting immense pressure on systems integrators to deliver reliable results.

Jens Pilz, Sennheiser’s spectrum policy and standards manager, points to a frustrating disparity between Pro AV and other technology sectors. "Other wireless industries ask for new spectrum with each generation of their technology," he said. "The Pro AV industry is forced to stick to the same spectrum resources—or lose spectrum while other industries gain it, like Digital Dividend 1 and 2 in Europe [when broadcast TV moved from analog to digital, freeing up spectrum] or 600 MHz in the U.S. [the same]."

Consequently, as governments globally reallocate valuable RF spectrum, often to support mobile data, wireless microphone operators are being squeezed into smaller frequency bands. This reallocation makes finding clear frequencies incredibly difficult, said René Moerch, group director of wireless for DPA Microphones and Wisycom. "The ability to find usable spectrum, what I often describe as 'parking spots,' is becoming one of the most critical challenges in Pro AV today," he explained.

Integrators are facing the same spectrum squeeze. “We [have to] find more channels in less space, both physically and in bandwidth loading," said Jason Jacquemain, design engineer for American Sound’s Venue and Entertainment Division. "Refining the quality and agility of systems to cope with more crowded RF environments is a frequent challenge that we must overcome."

According to Donovan, this reduction in available spectrum has forced a shift from convenience to intentional design. "Wireless systems can no longer be deployed casually in professional environments; they require planning, awareness, and a clear understanding of RF tradeoffs," he said. Donovan noted the industry has been driven to greater adoption of alternative frequency bands, recognizing there is no longer a single "best" solution.

Pushing Limits and Technological Shifts

Is there a hard limit to the number of wireless microphones that can be operated in the same space? No one knows for sure.

"There’s no universal number," admitted Ben Escobedo, Shure’s account executive for professional audio. "The limit is determined by available spectrum, system efficiency, regulatory rules, and RF conditions in the specific location. Ten channels might be easy in one room and impossible in another due to outside RF interference."

Lacking access to such a number, the best choice for Pro AV operators is to employ a mix of prudent signal coordination, system choices, and disciplined deployments that don’t use more wireless microphones than necessary. “That’s why planning and testing matter more than channel count on a spec sheet,” Escobedo told SCN. “Performing an RF site survey is essential to ensuring one can deliver the channel count and performance that the user expects."

To maximize channel counts within these tight constraints, manufacturers are focusing heavily on RF efficiency and RF agility. RF efficiency refers to how many channels can be packed into a single channel (typically 6 MHz in the U.S.). RF agility refers to wideband tuning, which allows wireless systems to scan a massive range of frequencies to avoid interference and congested areas.

Thanks to digital’s better spectral efficiency and advanced security features, the wireless microphone industry’s move from analog to digital has made room for more channels. Plus, manufacturers are introducing novel transmission standards to bypass UHF congestion entirely.

For example, Sennheiser is championing both WMAS and DECT NR+. Short for wireless multichannel audio systems, WMAS is a wideband, bidirectional approach that allows wireless microphones and in-ear monitors (IEMs) to operate within the same section of RF spectrum. DECT NR+ uses the 1.9 GHz range—a band largely exclusive to DECT technologies—to support bidirectional communication adapted for higher audio fidelity.

Pilz views WMAS and DECT NR+ as being complementary to each other, rather than competitive technologies. "In the core Pro AV world, these are more like tools in a toolbox, and for the right application, you need to select the right tool," he explained. "You shouldn't buy a product based on technology—you should buy the product based on your use case."

"Manufacturers are addressing RF complexity by both adding capability and reducing user burden," added Donovan. "On one hand, systems are becoming more sophisticated, with improved tuning control and coordination tools. On the other, they are becoming more automated, with features that simplify setup and ongoing operation."

Securing the Signal

Because Pro AV and broadcast applications are converging into unified, IP-centric environments, AV systems now routinely reside on corporate IT networks. This shift has raised security demands for wireless audio applications.

"Unencrypted wireless audio is no longer acceptable in many cases for both security and privacy reasons," said Escobedo. "Whether it's a major financial institution hosting a town hall in NYC or a pop star about to perform at a halftime show, digital wireless systems often provide AES-256 encryption to ensure secure transmission."

In this heightened security realm, users must understand the distinction between fully digital systems and digital hybrid systems. While fully digital platforms support AES-256 encryption, digital hybrid platforms prioritize absolute RF robustness and long-range resilience over encryption.

As a result, “digital hybrid technology does not support encryption," Moerch explained. "For that reason, Wisycom solutions are typically deployed in applications where RF performance and audio quality are the top priorities, while environments requiring encrypted transmission, such as corporate or government use, are better suited to fully digital systems with built-in encryption, like the DPA N-Series."

"Manufacturers are addressing RF complexity by both adding capability and reducing user burden," Donovan observed. "On one hand, systems are becoming more sophisticated, with improved tuning control and coordination tools. On the other, they are becoming more automated, with features that simplify setup and ongoing operation."

Interference and Disruption

Even the most advanced, heavily encrypted wireless technology will fail if deployed without paying attention to today’s congested RF spectrum. "It seems most designers are having to truly relearn the best practices as a result of said overcrowding, limits, and security concerns," said Jacquemain.

To ensure consistent and reliable service, end users and integrators need to adhere to strict deployment strategies.

Assess your real needs first. "A great starting point is a quick reality check on true channel count needs," Jacquemain advised.

Check the spectrum. Never rely on guesswork when deploying wireless microphones. "Knowing what spectrum is available where you’re working is critical, including avoiding DTV stations," Escobedo said. Using software tools like Shure’s Wireless Workbench or built-in system scanners can help find the most useful frequencies.

Place antennas properly. Maintaining strict line-of-sight between the transmitter and the receiver antennas is crucial, because human bodies and structural obstacles absorb RF energy. "Proper antenna spacing is also important for true diversity performance, which is typically around half a wavelength [approximately 20 inches in UHF ranges]," Moerch added.

Be smart about transmission power. Higher transmit power does not automatically equal better performance—it often just raises the noise floor. "In many cases we are finding it is preferred to use lower output power but have a more robust antenna receiving system,” Escobedo said. “Keeping the output power low may allow one to multiplex [reuse] the same frequency elsewhere in the deployment."

Know when not to use wireless. In those situations where microphone mobility is not necessary, it makes sense to use wires rather than going wireless. "A mentor of mine often pointed out that setting up a wireless microphone involves deploying four cables: power, two antenna cables, and an audio cable," said Escobedo. "Sometimes a simple XLR cable to a wired mic can suffice for the intended application."

Despite all this, it's still possible to use wireless microphones successfully through the use of planning, spectrum checking before going live, and leveraging innovative technologies like WMAS and DECT NR+. Just plugging in a wireless microphone system and hoping it works—especially if it's part of a system that's old and outdated—is a risky choice in today’s congested RF spectrum.

Ultimately, as Donovan said, "The most reliable systems are those designed with realism in mind, anticipating challenges rather than reacting to failures."