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EVENTS - USE OF RADIO MICROPHONES RADIO MICROPHONES - advice on using radio microphones. If you are just adding to your own system or including it as part of one of our systems it is useful to understand some very basic rules: · Each radio microphone is a complete system of microphone, battery powered radio transmitter and mains operated receiver. · The radio transmitter operates on a dry cell battery. We do not recommend re-chargeable batteries but good quality Alkaline dry cells such as those made by Maxell which we supply at very competitive prices. By all means use an old battery for testing but use a brand new one for the actual event. · The radio receiver operates on mains electricity (except those available for use with portable camcorders) and most of our systems are of the diversity type. That is they have two aerials and two receivers to eliminate loss of signal due to reflections in the room or due to blocking of the signal by large objects such as metal framed buildings. · There are two wave bands, VHF and UHF. UHF has more channels available for multiple operation of more than one radio microphones. Each microphone must have its own dedicated frequency within the two wave bands. Most of our systems are supplied with a frequency selection switch on both transmitter and receiver. By selecting different frequencies on each set multiple radio microphones may be used without interfering with each other or with others being used in the same venue but not necessarily in the same room. · If you use more than one radio microphone system you should use a aerial distribution system to avoid interference between each system. However using up to say 4 or 5 systems may be possible but only if you scatter the receivers apart, say about a metre apart from each other to avoid interference. Alternatively you could hire a number of microphones with the aerial distribution amplifiers and splitters provided such as the Sennheiser e550 system. This is supplied with just two aerials to set up and all of the receivers are in one rack case. · Radio receivers should be placed in line of sight of the transmitter and as close to the transmitter as possible. The audio output of the receiver will have to be connected to the microphone input of a mixer or mixer/amplifier · We are often asked what is the range of a radio microphone. This is not an easy question to answer - the basic range is about a radius of 100 metres from the position of the transmitter. But that would be in an open space, in an enclosed space such as a room or hall has walls which will deflect and reflect the transmission radio waves. Even in a small room you could get problems of lack of signal due to this effect. Even other objects in the room, particularly metal structures will affect the efficiency of the transmission signal. A room full of people can also affect the signal which is rather annoying after doing a test in the same room when empty. So each application is different. It is just common sense to move the receiver to a different position to clear these problems. With our diversity quality systems by Sennheiser your problems are usually minimal. Please also ensure you have read our GENERAL COMMENTS AND ADVICE FOR DUMMIES.
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