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Infrared Wireless Microphone Systems

Not so long ago, the idea of sending wireless microphone signals on light rather than RF seemed fairly exotic, but with the new RF spectrum constraints, corporate training facilities and large K-12 a 5/06/2010 8:00 AM Eastern

Infrared Wireless Microphone Systems

May 6, 2010 12:00 PM, By Bennett Liles




Atlas Sound Atlas Learn AL2430-2PH

Not so long ago, the idea of sending wireless microphone signals on light rather than RF seemed fairly exotic, but with the new RF spectrum constraints, corporate training facilities and large K-12 and university campus environments are appearing as more fertile ground for infrared wireless microphone systems. In response, the number of IR wireless systems has expanded, bringing in a wider range of options and features. Infrared wireless systems have their limitations, but in the right application—such as voice enhancement for multiclassroom instruction—they offer specific advantages that are unique to line-of-sight transmission, the top two of which are economical signal security and freedom from RF coordination issues. Instructors can roam freely from room to room without changing microphones or transmitters. In this survey, we have a look at what options are available in IR microphone systems for classroom instruction but exclude IR conferencing systems.

Designed for K-12 and higher-education classrooms, the Atlas Learn AL2430-2PH classroom security and sound-reinforcement system from Atlas Sound uses the AL-PH pendant/handheld microphone transmitter. This device provides local mobile control of mic volume, system volume, and mute settings through side-mounted soft-touch controls. Two AL-PH mic/transmitter units are included in the system. The receiver/amplifier has five sound source inputs for computer, TV/VCR, CD/DVD, aux, and paging, and 30W output power available on 8Ω, 25V, and 70.7V terminals. The page priority override mutes all other sound sources when a signal is present on the paging input channel. The AL-Dock unit is a wall- or table-mounted charging station that can accommodate two AL-PH microphones and four AA rechargeable batteries. Included with each system are two AL-IRDS dome sensors, each with a 10-meter-long RG-6 coax terminated in F connectors.

For applications requiring two IR wireless handheld microphones, the AWM6152 system from Audio 2000s offers two AWX6150 mics operating on 2.079MHz and 2.539MHz. The AWX6150 microphone uses two AA rechargeable NiMH batteries that can be charged by inserting either the base of the microphone or the batteries themselves into the ACC6152-01 charger. An LED indicator turns off when the batteries are fully charged. The AWR6152 receiver has two 1/4in. audio output jacks. If either is the only one connected, the output signal is a mono mix of both channels, but when both are connected, separate channels are output from each connector. There are four RCA infrared sensor connection ports and one IR sensor is included with the system. On the bottom of the receiver, there is a mic/line switch for setting the signal levels on the output jacks.

Azden IR-CS

Azden IR-CS

The IR-CS system from Azden combines the chest-worn IRN-10 mic/transmitter, the handheld IRH-15c mic/transmitter, the IRR-30P 2-channel receiver with power amplifier, and the IRD-60 dome sensor. Both mic units are 2-channel operating on 2.06MHz and 2.56MHz so they can be used simultaneously with the 2-channel receiver. CD/DVD players and other sources can be connected to the two stereo line-level inputs and played through the system along with the mics, and the receiver’s preamp level output can be used to feed videocameras. The main output can run four included ACS-6.5 in-ceiling loudspeakers or AWS-4.5 wall loudspeakers, delivering 5W to each at 4Ω. The dome sensor is powered from the receiver through the connecting RG-59 coax, and it includes a mounting bracket. The microphone/transmitter units each use two AA alkaline or rechargeable batteries to operate from 6 hours to 8 hours.

Bogen Enhancer

Bogen Enhancer

The Bogen Enhancer is an IR wireless system that includes the BCWBT body-pack transmitter, the BCHM headset mic, the BCLM lavalier mic, the BCBM body-pack mic, and the BCWHT handheld mic/transmitter. These all work with the BCWR 2-channel receiver, which has dual IR signal indicators, a mixed-channel output, separate channel volume controls, and two IR sensor coax inputs. The signal presence indicators light either red or green depending on whether the corresponding transmitter is turned on or off. The BCWBT body-pack transmitter has a channel-selector switch and a large IR emitter, and it runs on two AA alkaline or NiMH rechargeable batteries. The BCWHT handheld mic has a local on/off switch and an LED power indicator. Two BCIRS sensors are included, and each has a 35ft. cable.




Infrared Wireless Microphone Systems

May 6, 2010 12:00 PM, By Bennett Liles




Extron Electronics VoiceLift

Extron Electronics VoiceLift

The Extron Electronics VoiceLift microphone is a classroom-amplification system that is designed to operate with Extron’s PoleVault audio switcher/amplifiers. It consists of the VLP 102 pendant mic, the VLR 102 receiver, the VLR 102 SR optional secondary receiver, and the system charging station. The VLP 102 mic, which can also be handheld, features a volume control, a power switch, an extra microphone input, and an additional auxiliary line input for sources such as MP3 players. The VLR 102 receiver includes the IR sensor, and it has RJ-45 connectors on the back for porting the audio signal to the PoleVault switcher and for connecting a secondary receiver. The rear panel of the receiver also has captive screw connections for RS-232 linked configuration, an auxiliary audio input connector, a contact-closure sensor, and a relay output for activation of external devices. Either alkaline or rechargeable nickel metal hydride batteries may be used. When the microphone is powered with a NiMH battery, the charging station can charge two mics at the same time.

FrontRow Symbio 5201R

FrontRow Symbio 5201R

A division of Phonic Ear, FrontRow offers the FrontRow Symbio system for classroom use where space is limited and installation must be quick and easy. The 940TM pendant microphone/transmitter has an adjustable neck strap and operates on one AA NiMH battery or a single AA alkaline battery. The unit connects directly to a battery charger through a 1/8in. mini port, and it includes an auxiliary audio input and mute button. The system can include the optional 950H handheld microphone to use the second channel in the receiver. The 950H has three audio gain settings to adjust to how closely it is being used and the volume of speech, and it features a 1/8in. mini auxiliary audio input for a portable MP3 player. The 950C charging unit can charge both the pendant and handheld microphones at the same time. The Symbio 5201R receiver can accept up to three IR sensor lines on RCA connectors, and it includes a 1/4in. auxiliary audio output with a mic/line-level switch.

Lightspeed Technologies Redmike

Lightspeed Technologies Redmike

Using standard IR carrier frequencies 2.06MHz and 2.54MHz, the 2.1oz. Redmike from Lightspeed Technologies is part of the Redcat classroom audio system. The Redmike VC version has a two-button volume control that raises or lowers the output by 2dB with each button push. It also features an auxiliary audio input. The Redcat receiver sits on a tabletop and has IR sensors on both sides and offers two stereo audio inputs, one with RCA connectors and the other through a 1/8in. mini. The center section puts out the audio signal from a 20W amplifier with a 20Hz-to-13kHz frequency response, and there is also an aux out 1/8in. mini jack with a volume control. The system can also use the LT-71 LightMic pendant or the HM-70 handheld microphone. The microphones can use either AA alkaline or NiMH rechargeable batteries, and the charger unit can charge two Redmikes in the cradle while also charging an HM-70 or LT-71 through an external cable.

The Nady Systems IRW-220X is a 2-channel infrared wireless microphone system operating on 2.0MHz and 2.6MHz with an audio frequency response of 60Hz to 12kHz. The IRW-HT6X unidirectional dynamic handheld mic/transmitter has a multiple-LED-emitter array, an LED power indicator, and a steel mesh ball screen. The IRW-LT6X body-pack transmitter may be either belt- or lanyard-worn, and it includes a 1/8in. mini jack for the microphone connection and an audio input volume control. Both microphone models will operate for up to 5 hours on two AA alkaline or NiMH rechargeable batteries. The IR-220X receiver has separate volume controls and IR signal reception LEDs for each of its two channels. The unit has two rear-panel RCA connections for the included IRW-1S infrared sensors, which come with wall-mount brackets. The rear panel of the receiver has a channel-mixed audio output, and each audio channel includes a screwdriver-adjustable level control.

OWI markets the CRS-101 infrared wireless mic system as a complete IR solution with minimal installation required. At the center of the system is the CRS-CASE amplified audio mixer including separate level controls for wireless mics, the line-level input source from two RCA connectors, the TV/DVD 1/8in. mini input, and the 1/8in. mini input for computer sound. The unit has two pairs of binding post loudspeaker output terminals and three mini jacks for connection of the CRS-IRS sensors, each of which has a 50ft. cable and a green LED that lights up to indicate that the connection is good and the system is active. The CRS-PMIC pendant mic can be used as a pendant mic or as an IR transmitter for a connected headset or lapel mics. The pendant mic can be connected through a mini jack to the included CRS-PCH 6VDC charging power supply. The optional CRS-HHMIC handheld micro-phone may be used at the same time as the pendant mic in the other IR input channel of the receiver.




Infrared Wireless Microphone Systems

May 6, 2010 12:00 PM, By Bennett Liles




Panasonic WX-LT350

Panasonic WX-LT350

The Panasonic infrared wireless microphone series consists of the WX-LT350 pendant microphone, the WX-LT150 handheld microphone, the WX-LZ150 battery charger for microphones, the WX-LS100 infrared ceiling sensor, the WS-EC10 ceiling loudspeaker, and a choice of three receiver models. The WX-LA50 is a 2-channel IR tuner with a built-in 50W amplifier and four line inputs along with eight loudspeaker connections. The WX-LA20 receiver has a 2-channel tuner, four loudspeaker connections, and two line inputs. Either of these models can be connected with the WX-LR100 receiver to add two more channels for 4-channel operation. In addition, as a portable all-in-one model, the WX-LP100 has a 2-channel tuner, two line inputs, and one built-in loudspeaker. Working in the 850-nanometer wavelength range, the microphones can transmit on 2.3MHz, 2.8MHz, 3.2MHz, or 3.8MHz PFL synthesizer-selected channels to the sensor up to 8 meters away. The microphones are unidirectional electret condenser types, and they can operate on one AA dry element or nickel metal hydride rechargeable battery for up to 6 hours or an alkaline AA battery for about 5 hours. When switched on, the battery indicator LED on the microphone will show green for normal battery condition, orange for a low-battery warning, and red for a battery-depleted or battery-change warning.

TeachLogic offers the Maxim II system as an all-around sound-control system for two IR wireless mics and three other audio sources. The IMA-420 receiver has separate level controls for each wireless mic channel and controls for computer, DVD/TV, and auxiliary sound sources. In addition, it has a rear-panel 5-band graphic equalizer and a paging input from 25V, 70V, or 100V systems that automatically mutes other sources when a paging signal is present, and there are two 16W power amp outputs. The front panel includes a line-level output with a level control. Microphones include the IRH-30N handheld mic/transmitter, the IRT-89 pendant mic, the IRB-30 body-pack transmitter with a volume control and external audio input, and the IRT-30 crescent neck-worn microphone/transmitter. There are drop-in chargers for the body-pack transmitter and handheld mics.

The latest infrared wireless microphone system from TOA Electronics includes the IR-200M handheld microphone, the IR-300M neck-worn mic/transmitter with an internal mic and connection for an external lapel mic, and the IR-702T 2-channel infrared wireless tuner operating on 3.1MHz and 3.5MHz. The tuner has two outputs, one of which has a channel-mix switch. For larger systems, the IR-700D infrared wireless distributor, used in conjunction with the YW-1022 or YW-1024 distributor, can allow up to 16 IR receivers to be used. These may be the IR-500 wall-mount, the IR-510R ceiling-mount, or the IR-520R wall- or stand-mount receivers. The microphones can use two AA alkaline batteries, or with the IR-200BC charger, rechargeable batteries may be used.


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Installation Tips

Lighting
Wall- and ceiling-mounted IR sensors work best when shielded from bright sunlight coming in through windows, but they can use reflected infrared light from the transmitter so mounting sensors on a black, light absorbent surface is not recommended.

Incandescent lamps emit light that is near infrared and can sometimes interfere with IR sensors directly exposed at short distances, but mercury or fluorescent lighting should pose few if any problems.

Sensor Placement
Multiple sensors will most likely be needed in order to maintain line of sight no matter which way the presenter turns. One on the wall behind the presenter and one on the ceiling in front is a good starting scheme. Some experimentation in specific environments will be necessary.

IR Sensors
These, like microphones, have specific IR pickup patterns that should be used to best advantage in dealing with specific lighting conditions.

Sensors are usually connected to IR tuners with coaxial cable such as RG-59. With multiple sensors, the cable length from each to the tuner should be equal. Total signal attenuation should not exceed 12dB. —B.L.




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