Indian Institute of Technology Hyderabad SPEAKER & AMPLIFIER Ayush Saini- CH12B1005 Harmanpreet Singh-CS12B1017 Udhav Sethi-ES12B1022

Speakers  A speaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input.  A speaker is essentially the final translation machine -- the reverse of the microphone. It takes the electrical signal and translates it back into physical vibrations.

Components of Speaker  Diaphragm or Cone  Dust cap  Suspension  Spider  Voice coil  Basket  Magnets j

Working …  Passing of current through voice coil  Creating of magnetic field  Interaction between two magnets (permanent and electromagnet) causing repulsion and attraction  Change in current direction makes changes in force direction as well, pushes the coil to move back and forth rapidly  When coil moves, it pushes and pulls on the diaphragm  This vibrates the air in front of the speaker, creating sound waves

Amplifier  An amplifier boosts the audio signal and produces a more powerful version of it.  Amplifiers are found in several devices such as microphones, cd players, television etc.

Why is Amplifier needed?  Sound is transmitted in electronic devices by representing sound as a varying electric current.  A microphone diaphragm is moved back and forth using the sound signals and the microphone translates this movement into an electrical signal.  The electrical signal fluctuates to represent the compressions and rarefactions of the sound wave.  A recorder encodes this electrical signal as a pattern in some sort of medium.  A player re-interprets this pattern as an electrical signal and uses this electricity to move a speaker cone back and forth. This re-creates the air- pressure fluctuations originally recorded by the microphone. Often, the electric current is too weak to push the speaker cone back and forth. This is strengthened with the help of an amplifier.

Components  An amplifier consists of various components connected in a complex circuit.  The component at the heart of most amplifiers is the transistor.  The main elements in a transistor are semiconductors. Their varying ability to conduct electric current is a property that helps in the functioning of an amplifier.

Working Actually, an amplifier doesn’t actually boost the original signal. It generates a completely new output signal based on the input signal. There are 2 circuits - input circuit and output circuit.  The output circuit is generated by the amplifier's power supply, which generally draws energy from a battery. The power supply also generates an even and uninterrupted signal. The output circuit's load is moving the speaker cone.  The input circuit is the electrical audio signal recorded on tape or running in from a microphone. Its load is modifying the output circuit. It applies a varying resistance to the output circuit to re- create the voltage fluctuations of the original audio signal.

Pre- Amplifier  In most amplifiers, this load is too much work for the original audio signal.  For this reason, the signal is first boosted by a pre-amplifier, which sends a stronger output signal to the power amplifier.  The pre-amplifier works the same basic way as the amplifier.  The input circuit applies varying resistance to an output circuit generated by the power supply.  Some amplifier systems use several pre-amplifiers to gradually build up to a high-voltage output signal.

Thus a speaker and an amplifier consists a complete sound system. THANK YOU…