SIRENS AND SPEAKERS AND THERE TYPES What is a Siren? Siren is a device which makes loud prolonged signal or warning sound, In more simple words it is a loud noise making device. Sirens are basically used in vehicles, specially emergency vehicles such as ambulance, fire trucks and police cars.
Sirens are of two types, "mechanical" and "electronic" sirens. What is a mechanical siren? Mechanical sirens or Q-Siren are designed for far distance as they have high tone range and they project sound in all directions. Mechanical Sirens pumps air, compressing and accelerating it to many miles per. Basically the siren which is widely used are mechanical sirens, they consists of an electric motor which turns a rotor or impeller, which spins inside a slotted drum known as the stator. Rotor works as a centrifugal fan which pulls air into the siren axially through the intake portion, which then blows it though the holes in the stator. Now, the rotor chops the incoming air flow into impulsive bursts. When rotor and stator holes aligns, a burst of air is forced through and the frequency of these air bursts is known as the pitch of the siren. Volume and pattern of sound waves can be controlled by the operator.
What is an electronic siren?Electronic Sirens are for shorter distance, and it translate a transistor generated signal to an electromagnetic driver, which generally pulses a 3/4 inch diameter diaphragm back and forth producing sound waves which is then projected from the speaker. What is Speaker? A speaker is a device which converts an audio signal into sound. Electrical audio signal cannot be perceived by humans, so the signal need to be converted to sound waves which is audible to human ears. But before the signal is sent to the speaker the sound source must be amplified with an amplifier. Basically speakers are "active speakers" and "passive speakers" and also "powered speakers". What is an Active speaker?, An active speaker splits the frequency band of the audio signal into much smaller parts and then it is sent to individual speaker drivers designed to handle those frequencies. Active speakers are mostly suitable for home use like home theater. In an active speaker each driver has its own power amplifiers. What is a Passive speaker? Passive crossover components splits the audio signal and send each band directly to the speaker drivers. It has the arrangement of resistors, capacitors and indicators which splits the signal and send each frequency to the drivers and it requires a separate powered amplifier to send the full audio signal to the speaker. Passive speakers have some sorts of drawbacks like it is not user friendly and the various parts needs to be assembled by the user if they want to use it as home theater, and it also dissipates heat. What is Powered Speaker? A Powered speaker is one that has its own amplifier built into speaker and thus, plugs into a nearby outlet. But it is not necessary that a powered speaker is an active speaker, as the crossover components can be passive.