Speakers

What are speakers? You might say they're the ones from where the sound comes. Quite right. In technical terms, it is a transducer which converts electrical signals into their equivalent acoustic (mechanical waves) signals. This waves are produced by a diaphragm which moves back and fourth. There is a coil connected with diaphragm. In this way, it acts as a electromagnet and when current is passed through it, it moves back and fourth. So when we pass a signal of audio frequency, the speaker produces mechanical wave (or vibration) which is equivalent to the electric signal.

Cross section of a speaker

That's the basic of how speakers work. Now there are many type of different speakers. But regardless of its type, all do the same work : produce audible sound according to the electric signal fed.

Speakers can be classified in mainly ways : According to frequency they can work on and according to their impedance.

(1)According to frequency, there are three types: Woofers,mid-range and tweeters. Woofers work on low frequency audio signal. Mid-range are good for medium frequency and tweeters are good for high frequency audio signals.

Woofer

Mid-range

Tweeter

(2)Each speaker has impedance. It can be 32 ohm, 16 ohm, 8 ohm, and 4 ohm. 32 ohm speakers are generally used in headphones. 16 ohm speakers are used in telephones etc. 8 ohm speakers are used in general purpose music systems like the one we use in our home. And 4 0hm speakers are used in loudspeakers where loudness is required.

To drive the speakers, an adequate signal is required in terms of the power. We have to amplify the weak signals to be able to drive the speakers. That's where audio amplifiers are used.