The job of a PA system is to take a weak audio signal such as that produced by a vocal, convert it into an electrical signal, increase the size of this signal and convert it back into sound energy at a significantly greater volume. A PA system is made up of a number of components of which it is the job of the amplifier to increase the size of the audio signal and the speakers to then convert this signal back from electrical energy to sound energy. If the amplifier and speakers used in a particular PA system are not properly matched in terms of amplifier power output and speaker power rating then speaker damage can occur resulting in potentially expensive repair bills or even the requirement for replacement speakers. This article will discuss the basic theory behind speaker and amplifier ratings, the reasons why speaker damage occurs and how to match an amplifier or speakers to produce the best possible sound quality and lowest possible chance of speaker damage.
Audio signal amplifiers take a small electrical signal and by using a series of transistors ultimately produces an electrical signal that recreates the voltage fluctuations of the original but of a much higher power http://itsnews.co.uk/. Speakers work on the electric motor principle whereby the electrical pulses from the amplifier are channelled through a coil of wire creating magnetic energy in the form of an electromagnet. This coil is then attracted or repelled from a second fixed magnet creating vibrations in the paper cone to which it is fixed which in turn transfers energy into the surrounding air molecules resulting in sound.
Both amplifiers and speakers are given ratings in terms of the power they are capable of supplying or their ability to cope with the power supplied to them. Power is measured in Watts (W) and is the rate at which energy (measured in Joules) is converted from one form to another. For example 1 Watt of power is the equivalent of 1 Joule of energy being converted per second or 10 Watts of power is the equivalent of 10 joules of energy being converted per second.
Sure, you want the best possible speaker for whatever your budget might be. A dynamic or informative speaker generally is a stellar investment in the success of your meeting. But, sometimes your budget is not enough for the speaker you want. What’s the solution? Hire a less expensive speaker–squeeze the speaker you want for a better price–think beyond conventional wisdom?
Thinking beyond conventional wisdom might look like, limiting the number of speakers at your meeting. It is always less expensive to have a single speaker do several sessions than to have several speakers present a single session each. Not that every speaker is capable of presenting multiple sessions, however because of the multiple travel and hotel rooms cost, sometimes it is even cheaper to hire a speaker to deliver multiple programs than to have several non-paid speakers participate in your meeting. Even if these unpaid speakers drive in, thereby eliminating their airline travel expense, they will still want a free hotel room for the conference and free registration. Perhaps they were going to come anyway? You would have then received their conference registration dollars. Sometimes the true cost of non-paid speakers is staggeringly hidden.
Let’s explore the difference between a professional speaker presenting the same program multiple times vs. presenting multiple programs. The big difference for the speaker is preparation time–including: research, handout development and PowerPoint preparation. Unfortunately, few meeting planners take this key time issue into consideration. Speakers are selling both their knowledge and their time. The latter is finite, so the more you consume, the more you should expect to pay. In paying for a speaker’s time, you have to consider presentation time, travel time and preparation time. Unless of course you want a canned speech, then the preparation time is not an issue. Before you jump on the cost savings of a canned speech, remember that today, few attendees will tolerate a canned speech.
This idea of a single speaker presenting multiple presentations for a single fee is growing in the world of professional speakers but is counter to standard operating procedures for most speaker bureaus. If you like this idea, you might have to abandon the ease in speaker selection that you have enjoyed when working with bureaus.