The document discusses loudspeakers and their characteristics. Loudspeakers are transducers that convert electrical audio signals into sound waves. Key characteristics that determine a loudspeaker's performance include efficiency, frequency response, distortion, directivity, impedance, and power handling capacity. Loudspeakers have a cone connected to a coil that sits in a magnetic field. When an electrical signal is applied to the coil, it creates a magnetic field that interacts with the driver's magnetic system to move the cone back and forth, reproducing the sound. Dynamic loudspeakers are the most common type and work by applying a varying electrical current to the coil in a magnetic gap to generate sound from the cone.

1. LOUDSPEAKERS

2.  Introduction:
• Loudspeaker is a very important device present in
any audio and video system such as public address
systems, radios, televisions etc. It convert back the
electrical signal into acoustic signal which is the
original signal and the required signal after necessary
amplification and signal processing.

3. 3.1 Characteristics of Loudspeakers:
 Loudspeaker is a trasducer which converts
electrical signals of audio frequency into
sound waves of the same frequency.
 A loudspeaker’s performance is determined
by the following characteristics:

4. 1.Efficiency:
It is defined as the ratio of output sound
power to the input audio(electrical power).
2. Noise:
The unwanted sound, not contained in the
input signal but present in the output of the
loudspeaker is called noise. The mechanical
parts may vibrate at some resonant
frequency, causing noise. What is more
important is signal to noise ratio (S/N)
which is defined as the ratio of ‘signal
output’ to the ‘output of noise in the
absence of signal’.

5. 3. Frequency response:
It indicates loudspeaker’s response for the
audible frequency range of sound. Ideally,
response of a loudspeaker should be flat within
+ 1 dB for the frequency range of 16 Hz to 20
kHz . However, due to mass of the diaphragm
assembly, high frequencies are attenuated.

6. 4. Distortion:
Any change in the frequency, phase and
amplitude complexion of the output sound as
compared to the input audio signal is called
distortion.
5. Directivity:
Ratio of actual sound intensity at a point in
the direction of maximum intensity to the sound
intensity that would have been available there,
had the loudspeaker been omnidirectional.

7. 6. Impedance:
This input impedance of the loudspeaker is
represented in ohms and is an important
parameter, as its matching with the impedance of
source amplifier is necessary.
7. Power handling capacity:
A loudspeaker can handle some
maximum power (indicated in watts) for which it
is designed. Power more than the maximum will
damage the speaker.

8. Functional parts of a loud speaker
• Front parts includes a fabric, plastic, paper, or light
weighted metal cone .
•Outer parts of the cone is fastened to the outer parts of the
loudspeaker ‘s circular metal rim.
•Inner parts is fixed to an iron coil(voice coil) that sits just in
front of a permanent magnet (field magnet).

11. 1) Dynamic Loudspeaker:
• Dynamic loudspeaker are divided into two varieties.
Electro dynamic loudspeakers
Permanent magnet(PM) loudspeakers.
•Both work in exactly same way, the difference is in the
construction .
It has a light weight diaphragm, or cone,
connected to a rigid basket, or frame, via a
flexible suspension, commonly called a spider,
that constrains a coil of fine tensile wire to
move axially through a cylindrical magnetic
gap.

12. • When an electrical signal is applied to the voice
coil, a magnetic field is created by the electric
current in the voice coil, making it a variable
electromagnet.
• The coil and the driver's magnetic system
interact, generating a mechanical force that
causes the coil (and thus, the attached cone) to
move back and forth, thereby reproducing sound
under the control of the applied electrical signal
coming from the amplifier.

15. Electrodynamic Speakers