Audio engineers and wireless mic manufacturers have been dealing with a lot of bad news from the FCC (Federal Communications Commission) since the first announcement in 2010 that narrowed the available operational spectrum for wireless audio transmitters and receivers. After having to vacate the 700 MHz band after this announcement, more bad news came in 2017 when the 600 MHz band had to be vacated as well. This caused increasing headaches and complications in managing wireless frequencies in audio installations and touring rigs, with lots of gear being made illegal and needing to be retrofitted or disposed of for new equipment. Without these two bands, wireless frequency management for professional audio became even more complicated, especially in larger setups and urban areas.
…approval of Wireless Multichannel Audio Systems (or WMAS) is redefining moment for the professional wireless audio industry.
Manufacturers began responding in 2011 by developing the first digital professional audio transmitters and receivers. This technology helped by using the 900 MHz and 2.4 GHz bands. However, competition from other unlicensed devices operating at that same bandwidth didn’t solve the need for consistently reliable wireless audio. Latency was also an issue in less expensive digital systems. Latency is the delay inherent in changing an analog signal into a digital one and vice versa. This was apparent when the audience saw someone speaking on stage, but the audio from the speakers did not precisely match their lips.
Part of the problem with declining available bandwidth and higher competition for available frequencies is that wireless audio systems were solely based on a narrow-band operational technology. This technology uses a singular carrier wave featuring a fixed bandwidth of 200 KHz. One of the problems of wireless technology is the creation of distortion in other parts of the frequency band, called intermodulation distortion. With such a narrow band of operation, intermodulation frequency interference happens across the wireless spectrum, taking away usable frequencies for clear audio transmission. The more narrowband devices are introduced into a space, the more issues with intermodulation distortion.
Having a new wireless audio technology to help churches deal with RF issues and interference and provide clear, reliable wireless audio answers many church techs' prayers.
You get what I’m saying. Audio manufacturers faced a complex and competitive wireless environment trying to provide crystal clear audio with many frequencies deemed unusable because of intermodulation. This is why the FCC’s declaration in February 2024 regarding the approval of Wireless Multichannel Audio Systems (or WMAS) is such a redefining moment for the professional wireless audio industry.
WMAS is a technological leap forward because it no longer limits wireless audio transmission to a singular carrier wave fixed with an RF bandwidth of 200 KHz. WMAS uses a multi-carrier approach for wireless audio transmission where a diverse spectrum of RF (radio frequency) bandwidths can be as broad as 20 MHz. Why is this carrier wave bandwidth change in WMAS a big deal?
Sennheiser's technical application engineer Chris Phillips says, “Spectera is our first WMAS product. It is a bidirectional design. So, in the same 6 MHz wide carrier, you can do multiple channels of IEM, stereo or mono, mono IFBs, and microphones bidirectionally in the same carrier. We can also send control data back and forth between all devices."
Chris Phillips of Sennheiser USA puts it this way, “the goal of WMAS is to use the wireless spectrum more efficiently so you can get multiple audio links within the same wireless carrier, thus being much more spectrally efficient with a wide carrier band.” Nick Wood of Shure explains further by stating, “WMAS focuses on spectrum efficiency, which is like the miles per gallon analogy for wireless microphones in that you’re trying to go further with what you have available to use. WMAS allows new degrees of freedom to innovate. It should unlock innovation, which is good for everyone, and kind of changes what we can do with the spectrum we have as a manufacturer.”
“We are able to develop a body pack that you can plug your guitar into and have it be your IEM at the same time.” - Chris Phillips, Technical Applications Engineer, Sennheiser USA
The freedom to innovate that the FCC’s new WMAS declaration has opened allows manufacturers to coordinate frequencies like never before. Wood explains, “WMAS, in addition to narrow band, gives manufacturers the freedom to provide a broader range of solutions to fit the RF environment that an audio engineer finds themselves in. I wouldn't want to say that a wideband signal is the correct answer for every situation. You must have the right spectrum available to park that wider WMAS signal. In some cases, it might simplify the task. In others, it may become more about how you want to use that wideband signal with other narrow band solutions.”
The broader carrier wave in WMAS has allowed manufacturers to jump on the beginning of a wave of technological advancement that will wash over all segments and price points of the pro audio market. Wood explains how Shure’s upcoming Axient Digital PSM Advanced Digital In-Ear Monitor System can use WMAS technology, “We used every available technology available to us to make the best in-ear monitor that we could. And that includes a WMAS feature with a spectrum efficiency benefit and scalability.” Wood further states, “Axient Digital PSM provides RF strength for the most challenging RF situations. Its transmitters and True Digital Diversity bodypack receiver digitally combine four discrete stereo RF signal paths for greater coverage while defending against multipath interference. It’s almost like having eight mono channels available to create this fantastic stereo field in your ears. This allows freedom of expression for the storyteller and the performer and the ability to move while having reliable monitoring.”
Phillips explains how Sennheiser is riding this new WMAS technological wave. “Spectera is our first WMAS product. It is a bidirectional design. So, in the same 6 MHz wide carrier, you can do multiple channels of IEM, stereo or mono, mono IFBs, and microphones bidirectionally in the same carrier. We can also send control data back and forth between all devices. We couldn't have developed these systems within the narrow band 200 kHz carrier. We are able to develop a body pack that you can plug your guitar into and have it be your IEM at the same time. It's working in parallel. And those audio links are entirely separate for digital IEMs, which has been a challenge for a long time because of latency. We can get stereo digital IM down below 1 millisecond of latency. So, with the new framework, we can develop systems that can push that technology forward, especially in the IEM space. Also, with how we create the system, we have a one RU module that controls everything.”
Shure’s upcoming Axient Digital PSM Advanced Digital In-Ear Monitor System can use WMAS technology, “We used every available technology available to us to make the best in-ear monitor that we could. And that includes a WMAS feature with a spectrum efficiency benefit and scalability," shares Nick Wood, Product Manager, Shure.
Another interesting development with WMAS technology is the ability to handle intermodulation interference within the wideband signal, which does not create other unusable frequencies outside that wideband in the RF spectrum. “With narrowband systems, you would use software to coordinate frequencies to avoid intermodulation. Now, that wireless audio can be on one wideband carrier wave. It doesn’t generate other intermodulation interference outside that carrier. It makes frequency coordination a lot easier.” Wood adds, “WMAS is a way for us as manufacturers to have more ways to solve problems within crowded RF spectrums. We want to understand what our users really need and solve for that. The goal is for us to provide this great technology, but to get beyond just the technology, and enable great audio experiences and great worship experiences.”
“WMAS is a way for us as manufacturers to have more ways to solve problems within crowded RF spectrums.” - Nick Wood, Product Manager, Shure
Finally, as with any new technology that comes onto the market, there is fear and trepidation that there won’t be adequate support to learn about the latest technology and how to use it effectively. “Shure is excited about our WMAS innovations coming out that will solve the problems our customers have voiced to us. We’re excited about getting in front of as many people as possible at trade shows and local dealers and integrators to inform and support our customers with this new technology. No matter where you are on the size of the install or touring rig, there's an opportunity for training. There's an opportunity for demo’ing. There's an opportunity to learn how to use our tools better in their given application,” says Phillips. Wood adds, “We will have the ability in the future to remote in and support in ways that we haven't been able to do before. We’re in the process of moving past the days when FaceTime or sending pictures of the rack to diagnose issues are gone. That's the goal: to be more efficient in supporting our customers.”
WMAS is an exciting leap forward in the audio industry after 14 years of dealing with the declining availability of the RF spectrum. Having a new wireless audio technology to help churches deal with RF issues and interference and provide clear, reliable wireless audio answers many church techs' prayers. Church technical leaders should continue to educate themselves and be ready to make smart, prayerful decisions about using WMAS as a wireless audio solution.
>> For more information on Shure’s plans for WMAS technology, click here: https://www.shure.com/en-US/wmas
>> For more information on Sennheiser’s Spectera product line, click here: https://www.sennheiser.com/en-us/product-families/spectera
