Microphones and other wireless AV systems have come a long way in the past few decades and are able to perform in ways that were seldom, if ever, considered when the technology was still young. Diversity reception, digital signal transmission, automatic channel selection, and miniaturization have all been milestones in wireless AV development. Likely the most significant challenge has been waves of bandwidth reallocation. The reduction in RF space has forced designers and manufacturers to be increasingly innovative and use some ISM space. There is plenty happening in wireless AV technology and the models here are among those at the epicenter of the action.
One advantage of the 2.4GHz ISM band is that it is license-free worldwide, and since guitars, keyboards and other instruments are as much a part of live performance as the vocalists, the AKG DMS100 Instrument Set is a familiar face at many events. Of course, the versatility of the system includes a hand-held mic version. Operating with 256-bit AES encryption within four channels of 2.4GHz ISM, this model adds Adaptive Channel Selection, diversity reception, frequency response of 20Hz-20kHz ±1dB, and up to 12 hours of operation on two AA batteries. 24-bit, 48kHz digital audio resolution allows the amplified sound to be every bit as good as the original instrument or vocal input. Push-button channel pairing is aided by color coding. A universal AC power adapter and instrument cable are included.
A 2.4GHz system that is scalable to 20 channels in HD mode is the Audio-Technica System 20 Pro with digital 24-bit/48kHz wireless operation. Standard mode of 10 channels can be used to minimize latency. Receivers can be mounted up to 328 feet away and connected via Ethernet cable or docked in the chassis and as many as five of the chassis can be linked to use simultaneously. Operators can switch between different transmitter configurations because each receiver channel can be paired with up to four transmitters. RF signal level, system ID, transmitter battery level, and system link status are all shown on the system ID display. Two chassis can be mounted in a single full-rack space using the supplied short and long rack ears.
The Audix AP41OM2L10A functions in the 522MHz-586MHz range, which it allocates into 106 pre-coordinated channels, and up to 16 systems can be simultaneously run. Using antenna diversity reception, the R41 single-channel or R42 dualchannel receiver uses a 32kHz pilot tone to keep it quiet when the transmitters are powered down. Full-bodied sound is output through balanced XLR and unbalanced 1/4in. connectors. The output level can be adjusted in a range of -12 to +9 in 3dB steps, and the RF reception range is about 300ft. The output audio is very clean with a signal-tonoise ratio of 105dB at 30kHz deviation, and there is a ground lift switch for the XLR terminal. The display shows channel, active antenna, RF/AF levels, lock/unlock security setting, and battery condition. The H60 hand-held is a 64MHz wide spectrum transmitter that covers both A and B frequency groups, while the B60 is the bodypack transmitter with the same specs.
For flexible conferencing applications, the CAD Audio WX1000GN is a UHF gooseneck microphone system running on any of 100 channels in the 550- 590MHz frequency band. All of this is automatically sorted out through its auto-scan and IR sync functions. Two AA batteries can keep it going for up to 12 hours and the onboard USB-C input can run on external power and charge compatible batteries. There is a red “active” LED to indicate that the mic is on. The WGN1000 system has a 30Hz-18kHz audio frequency response and there is a battery level indicator on the transmitter. The receiver’s front panel features a large LED screen displaying RF/AF levels, channel, frequency, mute status, and there is a similar display on the mic base unit.
Connected to CONVERGE Pro 2 audio DSP mixers via P-Link and to other audio devices through professional XLR and 1/4in. TRS balanced analog outputs, the ClearOne DIALOG 20 uses frequency-hopping spread-spectrum technology with no frequency license restrictions worldwide. Encryption provides security while the auto-scan feature finds open channels for best reception. This model’s extremely low latency allows it to be used with sound reinforcement systems without echo distraction. Powering can be from AA batteries or USB port-recharged NiMH AA batteries. The 2-channel Dialog 20 blends these features to make it perfect for cloud-based collaboration with Microsoft Teams, Zoom, WebEx, GoToMeeting, and other conferencing platforms. The plenum-rated receiver can be placed on or under a table, inside a credenza, behind a video display, or above a ceiling.
A well-proven UHF PLL personal wideband true diversity system, the Clockaudio CW 7001 is made up of the CW 7001T belt pack portable transmitter and the CW 7000R receiver. These can operate among 1441 selectable frequencies arranged in 6 groups with a maximum 23 channels in one group. Twin RF receivers eliminate dropouts and adjustable pilot tone squelch keeps down noise while a S.A.W. (Surface Acoustic Wave) filter blocks unwanted signals. The metal case is durable and roadworthy with balanced XLR and 1/4in. AF output terminals. CW 7001T transmitter power is selectable between 10 and 50mW. Included is the CL 6 cardioid condenser mic with its TA 4F mini XLR connector, tie clip, and foam windscreen. This mic has a 50Hz16kHz frequency response
Performers who are highly mobile and play instruments need to keep their mic close and their hands-free with the Electro-Voice R300-E UHF wireless bodypack system. This consists of the BP-300 metal bodypack transmitter, the HM3 head-worn omnidirectional microphone, and the R300 rackmountable diversity receiver fitted with XLR and 1/4in. outputs. This unit’s front panel display includes channel, diversity indicator, RF signal strength, AF level, lock indicator, and squelch level readings. The TNC half-wave antennas can be chassis or remote mounted and the EZsync one-step channel setup simplifies transmitter-receiver channel pairing. The system allows eight channels to be simultaneously used in a 16MHz wide RF frequency range. The BP-300 transmitter has an RF output of 8mW, and it can run for up to 14 hours on two AA batteries.
In some wireless microphone applications, size— or the minimum—does matter, and this is where the Lectrosonics DSSM digital wireless micro transmitter makes a large difference. This model is IP57-rated for moisture resistance, and it operates on more than 6000 available frequencies in the UHF band. The RF output is selectable as 50, 25, or 10mW and the IR link enables fast channel setup. Firmware updates are done through the Lectrosonics USB/Wireless Designer software. The transmitter’s input gain is adjustable in 1dB steps. Dock charging capability can be used for the LB-50 battery using the optional CHSDSSM transmitter and battery charging station. As many as four LB-50 batteries or DSSM transmitters can be charged at once. The display shows battery status as a green light that gradually turns red and then blinks red to show low battery.
Another high mobility product is the Line 6 XD-V75TR digital vocal wireless bodypack system that provides a 10Hz-20kHz (-2.5dB) frequency response and license-free 2.4GHz band operation. Two receivers can be mounted side by side in a single rack space while using 14 alwaysavailable channels. The receiver’s LCD screen allows channel setting, model selection, battery status, and other functions. Through two powered BNC antenna inputs and half-wave antennas there is channel scanning for RF coordination on large setups. Signal encryption assures privacy with Digital Channel Lock (DCL) technology. The selector button on the transmitter bodypack makes it possible to easily audition and choose from the available EQ filter models. 24-bit, 10Hz-20kHz compander-free frequency response is output from balanced and unbalanced audio connectors on the back.
The Mipro ACT-580H is a digital hand-held transmitter that works in the ISM 5.8GHz band while housed in a tough metal case with two top grilles. The first can be easily removed for cleaning and the other is connected to the housing by an external metal thread. It can be fitted with either the MU80A condenser or MU-59A dynamic modules. The transmitter power switch also activates the backlit LCD showing group/channel, available functions, battery status, and AF signal level. The mic can run on two AA batteries or a lithium-ion battery that recharges via a USB-C port at the bottom end next to the charging indicator. There is a colored channel identification ring at the bottom end of the housing. As might be expected, there is also push-button channel sync with the receiver.
More frequently in recent years, classroom instructors are choosing to use hand-held wireless mics, and the Panasonic WX-ST200 is a digital system designed primarily for this application. It has a tough but lightweight black housing. Using the 1.9GHz DECT (Digital Enhanced Cordless Telecommunications) standard for a stable RF signal, the mic runs on a single AA battery or on AA rechargeable Ni-MH batteries energized with the WXSZ200P charger sold separately. An LED on the housing indicates charging status while an adjacent LED shows power. These are located right next to the power switch. Inside the battery cover is a low-cut switch to alter frequency response. This applies a -6 dB/ octave gain on frequencies below around 200Hz. The pairing button quickly tunes the mic and receiver to each other. One interesting feature is the 3.5mm audio connection that can take the output of an external sound device and transmit this on the wireless link while the microphone output is overridden.
Completing the EW-DX line is the new Sennheiser EM 4 Dante which attacks the spectrum challenges with its Link Density (LD) Mode. Frequencies can be spaced at 600kHz intervals, but in large wireless setups LD Mode can pack them into 300kHz spaces. Under ideal conditions, the system can accommodate up to 146 channels in standard mode or up to 293 channels in LD Mode. Its power supply automatically adapts to the local power parameters while the four network ports provide more flexible configuration. These network modes include Control and Dante Primary combined (Single Cable Mode), Control and Dante Primary separate (Split Mode), Control, Dante Primary, and Dante Secondary separate (Redundancy Mode). After the initial frequency scan, the receiver auto-deploys free frequencies to all systems. Transmitters sync through BLE. Control and monitoring are handled with Wireless Systems Manager or Sennheiser Control Cockpit. Each EW-DX EM 4 Dante receiver puts four receivers into a single rack space.
From a traditional leader in the wireless mic industry, the Shure MXW neXt wireless microphone system works in environments from the big stage to the conference room, where it delivers wide response sound to both local and remote participants. The setup uses the APX4 or APX8 transceiver, 4-bay or 8-bay charging station, and 4 to 8 microphones which can be a mix of body pack, hand-held, boundary, and gooseneck types. IntelliMix DSP includes the full suite of DSP functionality including Dante, USB, and analog outputs. Both 4 and 8-bay versions of the networked chargers have a daisy chaining option. Each station accepts all Microflex Wireless transmitters. Through the Ethernet connection and control software, there is monitoring of battery charge status in hours and minutes. Overcharge protection is also provided.
A 10Hz-20kHz frequency response, 10-hour battery life on a standard 18650 Li-Ion battery, tuning range of 470MHz to 1525MHz, and AutoAssign channel setup are leading features on the Sound Devices A20- HH digital wireless hand-held microphone. A variety of heads can be used to tailor the mic style or pickup pattern. Sennheiser heads can also be fitted on this model by reversing the capsule collar. Body shell, control ring, and capsule collar are also interchangeable for further customization. Via a protocol called NextLink, transmitters can be powered up or down and frequencies changed from the house mixing position. The solid magnesium diecast, stainless steel construction, and impact-absorbing polycarbonate outer shell stand up to grueling road use. RF output power settings are Off, 2mW, 10mW, 20mW, 40mW, and 100mW. When not transmitting, the A20-HH can record audio internally on a micro-SD card.
Carrying a name always strong in RF sound gear, the Sony DWX digital wireless system operates in the UHF band with four codec modes and high-density channel assignments. Add to these features four codec modes, encryption, and networking capability. It can pack 21 channels into an 8 MHz TV band or 16 channels into a 6 MHz TV band. There is also support for the Dante multi-channel networking standard. The Wireless Studio software gives the operator full control over all system elements, including the antennas, receivers, and transmitters. Sony’s X-Dimension Diversity keeps the transmission reliable at the professional performance level.
The Yamaha Unified Communications RMWGL/WGS long and short gooseneck microphones are part of the 1.9GHz band RM-W wireless mic system and they are used for a wide range of meeting and conference formats. The RM-WGL is the 12in. version and the RM-WGS is the 6in. model, both of which excel at table mobility and background noise rejection. Each model accepts the included Li-ion battery which can keep the mic transmitting for up to 20 hours. This may be charged with the RM-WCH-8 charging system or through a USB-C port and the eight mics can be charged simultaneously. The whole system takes about 5 hours for a full charge. Each mic has an LED mute button and battery-level display. The LED mic identification ring may be set to any of three colors.
