Shure recently announced the availability of a new frequency band for its professional digital wireless microphone system, the ULX-D. While the current systems operate in the UHF band between approximately 470 – 696 MHz (in the U.S.), this new addition covers the unlicensed ISM band between 902 – 928 MHz. Given the pending changes in frequency availability, having the higher band available is an important step – bringing production-quality performance to an unlicensed band.
Why so important? The FCC's upcoming Incentive Auction, which is slated to begin next year, will repurpose most of the 600-MHz UHF television band for other purposes. When the change is fully implemented, wireless microphones will be restricted from operating in this band except under limited, special circumstances. Broadcast television stations currently operating in this spectrum will be moved to lower bands, with the likelihood of less open space there. Recall 2010's clearing of the 700-MHz band from wireless microphone use, when users were required to trade in or purchase new equipment in other bands.
Soon after its introduction in 2012, I had the opportunity to work with the UHF-band version of the ULX-D, and was very impressed with its audio quality and features. According to Shure, the 900-MHz version functions quite similarly. Below, I'll summarize what we're being told about the system's performance.
ULX-D Features
The ULX-D boasts a host of worthy features. The roadworthy 1-RU chassis, with internal power supply, holds two or four wireless receivers with practical front-panel controls. A half-rack, single-channel receiver is also available. Extensive application menus in both the transmitter and receiver offer a plethora of professional capabilities such as audio summing, body pack frequency diversity for redundancy, scanning modes, and custom frequency groups.
The rugged handheld and body pack transmitters provide user-selectable RF output of 1-mW (for very dense channel allocation at moderate distances), 10-mW, or 20-mW. Other aspects of the ULX-D system include transmitter encryption, both Ethernet and Dante digital audio networking capabilities, and a very clean, transparent implementation of digital transmission.
Audio Quality
Audio quality is the most important factor for the initial input into your sound reproduction system. With flat 20 Hz – 20 kHz frequency response and no companding from the 24-bit digital audio stream, the result is virtually identical to using the wired version of the mic – retaining the transient response and the character of the particular microphone capsule. Comparisons using three different heads on the UHF version transmitter and the wired versions of the same microphone bore this out. We would expect the same from the new 900 MHz edition.
In an A/B comparison between the earlier Shure professional analog wireless, the UHF-R, and the digital ULX-D, the audio response of the latter was full bandwidth and uncolored, and was an improvement in quality to the analog system. As with Shure's other professional handheld transmitters, a variety of easily replaceable microphone heads are available, from the ubiquitous SM58 to the elite KSM9, as well as heads from other manufacturers conforming to Shure's threaded concentric-ring mating connection.
The ULX-D has an extremely wide dynamic range of greater than 120 dB through its analog outputs. This dynamic range is made possible by Shure's Gain Ranging technology within the transmitter, which optimizes the dynamic range for any input source from quiet to very loud. This technology eliminates the need for gain adjustments in the handheld transmitter (the bodypack does have a selectable 12-dB pad). Gain Ranging is transparent; a shout will not clip the signal, and a soft voice is reproduced with no additional noise.
RF Output, Channel Density, and Range
Transmitters can be set to three RF output levels – 20 mW, 10 mW, and 1 mW. The lowest setting is especially useful when the transmitters are operating within a modest distance from the receiver antennas (or remote antennas), and are being used closer together; the lower power lessens the potential for intermodulation. The specified operating range for the ULX-D is 100 meters (330 feet) for the 10 mW transmitter setting.
To meet the requirements for the 900 MHz band, Shure needed to modify the RF channel-spacing scheme on this system from that used in the UHF version. With this scheme, up to 12 compatible channels can operate across the 902 – 928 MHz band. In High Density mode, using a 1-mW transmitter output, up to 73 channels can be supported if the ambient RF noise level is sufficiently low at the venue. Shure specifies a working range of up to 30 meters using this mode.
Digital Audio, Encryption, Networking
The ULX-D is enabled for Dante digital networked audio using the receiver's rear-panel primary and secondary Ethernet ports. Thus the audio signal can remain in the digital domain without conversion to analog from the transmitter through the receiver, and to a digital mixing console or other devices.
The ULX-D system allows Advanced Encryption Standard (AES-256) 256-bit encryption to be enabled when a secure wireless transmission is desired. The encryption is robust, fast loading, and is transparent to the audio.
Multiple ULX-D receivers can be networked to provide real-time monitoring and control of the individual wireless channels using Shure's Wireless Workbench software. Networking also allows scanning and group/channel selection across all receivers, with the best available frequencies automatically allocated for the particular location. Wireless Workbench includes a 900-MHz site survey tool, to assess the environment for other devices using that band that are typically frequency-hopping and operate with intermittent bursts – providing information on the best channel settings.
A Welcome Addition
The current wireless system is excellent: audio reproduction is natural and unaffected; controls and menus are well positioned and can be accessed quickly; and a host of capabilities from audio summing to encryption are offered. Assuming that Shure's 900-MHz ULX-D will match its current system, it offers users more license-free wireless channels for professional applications. Shure does recommend the new version mainly for indoor use, where the building provides more shielding from other users in the less predictable 900-MHz band. As for the future, with this latest ULX-D it appears that Shure is well-prepared for the upcoming wireless spectrum changes.
