2. Educational program: Mechanic - electrician Title of program: Technical training II. class The loudspeakers Worked out: Bc. Chumchal Miroslav Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/04.0002 je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.

3.  Function of loudspeaker  Types of loudspeakers  Speakers according to the frequency range  Cross- section of speaker´s basket  Students activities  Literature used

4.  Loudspeakers are electro- acoustic exchangers, which converted an electric power on mechanic power in sound form.  It consist from membrane, drive unit, which is supplied by input voltage from the final stage of the amplifier.  Earpieces are similar device.  Loudspeakers are divided by the form of emission on: - Directly emitting ( oscillating membrane is directly connected on setting, in which are acoustic energy emitting ) - Indirectly emitting pressure ( auditory is insert between membrane and surroundings. These loudspeakers have high efficiency and high emitted power.

5.  Loudspeakers are divided on: electrodynamics – by oscillating coil passing current in magnetic field and it cause membrane moving. electromagnetic – firmly placed electromagnet attracted membrane from thin iron sheet metal, electromagnet placed in the field cause the coils activities and membrane moving. electrostatic - membrane with conductive layer is placed between two electrodes. The loudspeaker working on attracting and repelling principle of electric charge desks. piezoelectric – desk from piezoelectric material is mechanically joined with membrane or it right constitute the membrane. plasma – without membrane. Use change in air pressure, caused by arc discharge.

6.  Broadband – range 20 – 20 KHz  Deep tone ( bass ) 20 – 5 KHz  Middle band ( centre tone ) 100 – 12 KHz  High tone ( high ) 2 KHz – 20 KHz, but even more

7. Airflowing by loudspeaker

8. Cross- section of speaker basket Oscillating coil with centr- tend membrane

9. Explain the function of the loudspeaker. What types of the loudspeaker do you know? Explain theirs function. Give the frequency ranges by individual loudspeakers. How difference is between the loudspeaker and earpiece.

10. Show and describe individual parts of loudspeaker on sample. How behave the speaker, when the low voltage is bringing on it from the source? Verify on a template.

11.  www.cs.wikipedia.org./wiki/Reproduktor www.cs.wikipedia.org./wiki/Reproduktor  Vlastní poznámkový sešit