Production sound mixers have a slick new option when it comes to wiring athletes in the field. If you've ever tuned in to a sporting event you might have seen the "mic'd up segments" where player reactions, comments, and funny moments are broadcast during the game. The NBA, NFL, NHL, MLB and NASCAR are famous for it as a way to immerse viewers at home as if they were sitting amongst the action.

The ZMT3-Flex from Zaxcom is a wireless transmitter specifically designed for that application, among others. 


The design touts an extremely thin (0.4" / 1.02 cm) and lightweight (3 oz / 85 g) profile while still providing the pro features we've grown to expect from the company. The tech is wrapped in a flexible silicon rubber that's bendable to maximize player safety. Wireless audio is transmitted over a fully digital signal. In fact, all Zaxcom wireless are digital. A benefit of this is encrypted audio. An analog signal, like those found in Azden, Sennheiser, and Sony are not encrypted, allowing anyone with a scanner to pick up the conversation and record it. Encryption adds an impenetrable layer of security protecting player privacy. 

Zaxcom ZMT3-FlexZMT3-Flex

Besides its wireless capability, audio can be simultaneously recorded internally to a microSD card. For us, this is the coolest feature in wireless audio. Since Zaxcom first introduced the technology over a decade ago, there's been dozens of copycats through the years. Simultaneous recording can be looked at as the dual card slot of cameras. If there's interference in the wireless signal, its clean internal recording serves as a backup. Additionally, you can record straight to the microSD card without transmitting a wireless signal.

You can connect up to two different lavs (not included), a single one in mono mode or two in stereo via two microdot inputs. Mono mode provides a 128 dB dynamic range and 108 dB in stereo with no limiting or compression distortion. Timecode is also supported along with advanced tech like ZaxNet that allows you to remotely control the transmitter. Things like input gain adjustments, channel selection, and playback modes can be changed without needing to take the transmitter off of the player. Power output is selectable in 25, 50, or 75 mW. 

Other cool tech included is ZHD (Zaxcom High Density modulation). No Film School has talked about the shrinking wireless spectrum in the past where the FCC has auctioned off frequencies to cellular companies. This leaves those in production sound, live concert venues, and theaters somewhat high and dry as the number of wireless frequencies have been dramatically decreased. In most cases, it's illegal in the U.S. to use equipment in certain frequency bands. Without getting too technical, turning on one of the ZHD modes expands the number of frequency channels at a location. This is especially important when you are in a sports arena with other wireless equipment competing in the same frequency band. It helps avoid interference. 

An OLED provides quick reference to frequency channel, battery status, and menu support. ZMT3-Flex runs off a rechargeable battery for up to 6 hours with around 24 hours of standby time. The unit is sweatproof and water-resistant and can be paired with a number of Zaxcom receivers

While the ZMT3-Flex isn't a first of its kind—Quantum5X offers a line of player and referee microphones—the added benefit of encrypted audio does tilt the edge to the Zaxcom model as privacy concerns increase. Quantum5X uses an analog signal.

Comparing the cost of the two brands, the Quantum5X regular PlayerMic is $2,495. The ZMT3-Flex is the same: $2,495. Beyond using the transmitter in sports, filmmakers can take advantage of its slim design while wiring actors in tight-fitting costumes like a dress or use as a plant mic in the visor of a car.