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The ATW-1452 is a low cost professional UHF band, hand held radio microphone system that helps meet the requirement for a reliable, robust and good quality audio link between audience / performer and the sound system, whilst meeting the latest health and safety requirements regarding the absence of trip hazards associated with trailing microphone leads. It works on the 864.00 MHz band and does not need a license to operate it provided you have a maximum of three microphones. The microphone itself is solidly constructed and is powered by a PP3 (9V) battery that will last for 18 hours or more in continuous use. Handling noise is very low and a small red LED mounted in the base of the microphone gives an indication of the battery condition. Also, the RF bar graph indicator on the receiver shows the exact battery condition - if you notice that the rf signal is gradually reducing over time then send someone out to buy a battery - quick! It is recommended that good quality alkaline batteries are used for longer life though not Duracell type as these will not fit. A second bargraph display shows the audio signal produced by the microphone and being sent to the microphone mixer. Used together, both displays confirm correct operation of the microphone and can be used to quickly spot problems during use (ie mic not switched on, battery failing etc.). Even the mains on/off switch is illuminated to confirm mains power is available! Two ATW-1452 receivers can be fitted side by side in a single 1U (1.25") 19" rack space.
Unlike cheaper non-diversity radio mics, the receiver unit actually has two seperate receivers built into it, each with an aerial to greatly reduce the risk of audio drop out or signal fade. As the microphone is moved, its output signal strength will vary and the receivers switch silently such that whichever is getting the best signal is the one used. A pair of lights on the front panel indicate which receiver is currently on (it is normal for the lights to jump between A and B during use). The aerials should be free of obstruction. Critically, the base unit should not be located close to any digital equipment (CD player, DAT machine etc.), otherwise poor performance may result as the receivers are swamped by spurious digital signals. It is not unusual to get a range in excess of 100 meters with a fresh alkaline battery. Both balanced and unbalanced outputs are provided and a level control on the front panel allows precise gain matching for the mixer input. An earth lift switch is provided to prevent earth loops (hum). A squelch (radio gain) control (fitted on the receiver unit - not the microphone) allows you to set the radio frequency gain to suit your location - set it high enough to avoid audio fade / drop out within the limits of your hall but not too high as you might (very unlikely) pick up the local kareoki bar down the street! The squelch control is usually a small screwdriver slot type adjustment and is very inconspicuous - if in doubt read the instructions!
Note that each microphone has its own associated receiver - you cannot use two microphones into a single receiver! So if you require two roving wireless microphones, you need to purchase two complete systems each of which works on a different frequency. You MAY though purchase both a hand held AND a headworn hands free microphone with beltpack transmitter, both to work on the SAME frequency (and hence share a receiver), but what you CANNOT do is to have them BOTH working at the SAME time!! If you try this, chronic interference will result with various whistles and screams and no intelligeable audio. Note also that whilst headworn microphones will work well in a small hall, lavalier types (like you see news presenters wearing on the TV) will NOT, and will be very prone to feedback problems.....Feedback - How to reduce it
Sensitivity - Note that the microphone has a small plastic trimmer that allows you to set the audio level to match how the microphone is used. If used for a DJ or loud singer for example, you may need to turn the audio down to give a clean (distortion free) output at the loudest level. Use the audio indicator lights on the receiver to set this up such that three or four lights come on at the absolute loudest input you will have......Back to Top
Connections - You will need to buy either a jack plug (mono type) for unbalanced output connection (not recommended) or a Neutrik XLR (Female in line) type for a balanced output. This connects via some good quality screened cable to the sound system input.
Be very careful when trying to use unbalanced microphones with balanced inputs. Remember that a microphone input which may be phantom powered, will put up to 48V dc into your microphone and directly across the capsule of an unbalanced dynamic mic! Make sure you understand what you are trying to achieve BEFORE damaging anything!
Safety Statement.....Back to Top
Legislation in the UK is getting ever tighter from a health and safety point of view such that criminal proceedings are now likely to be taken against anyone, or any responsible overseeing body, who fail to guard against a preventable or foreseeable accident, especially in a public place. Trailing microphone wires present such a hazard in normal use, but given the conditions of an emergency building evacuation, in low light or poor visibility and by both the agile and physically challanged or elderly, then the probability of an incident rises dramatically. By changing to radio microphones, you eliminate both the hazard presented AND the worry over possible litegation, not to mention the stress and trauma of dealing with the after effects. They are also easier and quicker to use!
Batteries - Are the number one cause of problems with radio microphones - always have a fresh spare battery available. Can I use a rechargeable battery? Yes is the answer to that but with some important caveats:
1 Use top quality NMH (Nickel Metal Hydride) industrial type batteries as they have no memory effect and can be topped up without adversly affecting performance.
Can I fit the radio microphone on a pole? Yes you can BUT:
Conclusion - Poles are not a good idea for radio microphones. It is far better to train the user in their correct use.
Radio microphones eliminate the trip hazard associated with long lengths of microphone wire BUT they need careful attention if you are to get the best performance from them. Modern true diversity types have built in features to eliminate outside interference from Taxis etc.. and have a sound quality every bit as good as a normal wired microphone. If you plan to use more than three radio microphones, then you will need to use a mix of three UHF (1400 series) and up to five VHF (1100 series) to avoid the need to pay annual licence fees.
2 Rechargeable batteries provide typically 8.4V dc output which is less than the 9V produced by alkaline or "off the shelf" bought batteries. This WILL affect performance in a number of ways that MIGHT cause problems and the only way to be sure is to experiment BEFORE going live.
Poles.....Back to Top
Putting an expensive, quality microphone on the end of a pole is asking for trouble - In time someone will inevitably try to rest the pole against a wall and the whole thing WILL fall down. You will get away with this for a while but over time, audio quality will degrade, perhaps unnoticably at first, feedback will get worse and the microphone may even start to fail intermittently. Over time, those who cannot hear well or those struggling to catch the high frequency consonent edges which add so much to the overall clarity, will progressively miss more and more. Since this may be a gradual process, the loss is all the more telling as large sections of the audience miss parts of the spoken word.
Radio microphones are by nature meant to be held in the hand and used quite close to the mouth (2"). Also, since they contain a battery, they are heavy when fixed on the end of a long pole and can be difficult to hold for any length of time.
Using a radio microphone fixed to a pole invalidates the warranty if damage is sustained by dropping.
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