Look for a wireless PA system within your budget

Prices can vary widely for wireless PA systems, from less than $100 to thousands of dollars. You'll need to determine the number of microphones, speakers and the output needed to reach the estimated size of the crowd. The general rule is to use 10 watts of power per 100 people seated directly in front of the system; thus a system rated at 35 watts will handle an audience of up to 350. For crowds scattered to both sides of the system, increase the wattage by 40 percent. You may see a system rated at 10 watts RMS (root mean square) in product specifications. The RMS number is what's important, rather than PMPO (Peak Music Power Output), because RMS indicates how many watts the system is capable of delivering on a constant basis.

I recommend: Compare prices on different wireless public address systems and components at NexTag. If you're seeking small, portable PA systems, don't overlook DAK Industries, which frequently has interesting finds and bargains in electronics. 

Select a wireless PA system based on where you will use it

Buy an AC-powered PA system if the unit will be used exclusively indoors. On the other hand, if the wireless PA system will be used exclusively outdoors or both indoors and outdoors, consider the flexibility of a system that is AC/DC capable.

I recommend: Check DAK  for reviews of a VHF AC/DC system that sells for $99 and is suitable for reaching groups of up to 100 people.

Determine which portions of the system should be wireless

A wireless PA system can have wireless microphones but hard-wired speakers. If the primary concern is to increase the presenter's flexibility, incorporating hard-wired speakers will not be a problem. If it is necessary to run speaker wires throughout a venue, however, the cord length will limit speaker placement. This is not a problem if the speakers are in a permanent location with wires covered and protected. If, however, the speakers are mobile, the liability risk should someone trip over an uncovered cord needs to be weighed against the benefit of investing in a fully wireless PA system.

I recommend: Check out Califone for a true wireless system. This wireless public address equipment puts out 90-watts RMS of power, which can handle crowds of up to 500 people.

Check into outdoor wireless PA systems for emergency use

An outdoor wireless public address system can play an important role during emergencies or disasters. Research into variations of equipment to play prerecorded messages is underway, with one promising method developed for the Wireless Internet Information System for Medical Response to Disasters. During a drill in California, the WiFi Bullhorn proved effective for first responders.

I recommend: Go to PubMedCentral to learn more about the hardware and software specifications used in the outdoor wireless public address system WiFi Bullhorn for the Wireless Internet Information System for Medical Response to Disasters.