Speaker - Design and Principles of Use

3829 Words May 30th, 2013 16 Pages
SAE Institute Glasgow

The Dynamic Moving Coil Loudspeaker:
Design and principle of use – an audio engineer's best friend

Sergiusz Sytniejewski
16145
AF0911

Submission date: 11 September 2012

TABLE OF CONTENTS

Page
Introduction3
1. Driver plus box equals loudspeaker4
1.1. Driver5
1.2. Cone6
1.3. Surround7
1.4. Rear suspension (spider)8
1.5. The chassis8
1.6. Voice coil assembly9
1.7. Magnet10
2. Baffles10
2.1. Infinite baffle11
2.2. Ported enclosure11
2.3. Drone cone11
2.4. Bandpass cabinet12
3. Crossover12
4. Conclusion12
5. References14
6. Bibliography14

Introduction

You wouldn't think a loudspeaker and a car engine have a lot in common, would you? Well perhaps not a lot but they definitely
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Magnet - creates a magnetic field. The stronger it is the higher efficiency and accuracy of a speaker. It is worth noting that nowadays this is a permanent magnet as opposed to the earliest designs which used electromagnets. The most common and cheapest material used is ferrite but the most effective are alnico magnets (consist of aluminium–nickel–cobalt hence the name). Field gap – should be as small as possible to enhance magnetic induction hence improving the speaker's efficiency. Voice coil – mounted on a bobbin. This makes the system move while AC passes through. It consists of turns of copper or aluminium wire. Different cross-section wires are used. Round is most commonly used but to pack it more densely square wire (flat) is used, while hexagonal provides the best heat dissipation. Bobbin – is a short tube to which the voice coil is attached. The bobbin is connected to the centre of the cone. The most common materials used are plastic, aluminium and paper. Surrounds – these keep a cone centred and control its maximum moving range. Can be made of many different materials such as butyl rubber, synthetic foams or PVC. Spider – prevents voice coil from touching the magnet and maintains centralisation. Usually made of corrugated pressed fabric. Cone – makes changes of air pressure while moving back and forth. It has to be stiff and lightweight. Commonly made of paper pulp,
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