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Prepared by: David D. Bradshaw Dept. of Electrical and Computer Engineering Utah State University

ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Loudspeakers. Prepared by: David D. Bradshaw Dept. of Electrical and Computer Engineering Utah State University E: davbradshaw@cc.usu.edu ; T: ( 435)797-1000; F: (435)797-3054 (ECE Dept.)

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Prepared by: David D. Bradshaw Dept. of Electrical and Computer Engineering Utah State University

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  1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Loudspeakers Prepared by: David D. Bradshaw Dept. of Electrical and Computer Engineering Utah State University E: davbradshaw@cc.usu.edu ; T: (435)797-1000; F: (435)797-3054 (ECE Dept.) W: http://mechatoronics.ece.usu.edu 3/9/2007

  2. Outline • Reference list • To probe further • Major applications • Basic working principle illustrated • A typical sample configuration in application (application notes) • Major specifications • Limitations • Loudspeaker systems • Where to buy ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  3. Reference list • Yamaha Sound Reinforcement Handbook. Davis & Jones, 1989. Hal Leonard. • Sound System Engineering. Don and Carol Davis. 1987. Howard W. Sams and Co. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  4. To explore further • http://www.scrounge.org/speak/speak.htm • http://www.kbapps.com/construction.html • http://www.geocities.com/SunsetStrip/Stage/4241/Setup.html • http://www.sweetwater.com/shop/live-sound/8_steps_pa_system.php • http://www.audioholics.com/tweaks/speaker-setup-guidelines ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  5. Major applications • Sound reinforcement and public address systems • Alarm and security systems • Home and mobile audio systems • Home theatre systems • Voice and audio communication systems ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  6. Basic Working Principle A loudspeaker transforms electrical energy into mechanical vibrations that are propagated into the air http://www.privateline.com/TelephoneHistory/soundwaves.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  7. Sample Configuration Home theatre system: Principle A home theatre system consists of a loudspeaker array arranged in such a way as to simulate a natural acoustic environment. A sound distribution system sends electrical power to certain loudspeakers in varying levels to give the perception of reproduced sounds coming from a specific place. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  8. Sample Configuration Home theatre system: wiring diagram http://www.onqlegrand.com/jahia/Jahia/pid/1383 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  9. Sample Configuration Home theatre system: loudspeaker placement http://www.guardianhometechnologies.com/what-we-offer/Home-Theatre-Systems.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  10. Specifications Major Specifications: • Frequency response • Resonance • Nominal impedance • Power rating • Sensitivity ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  11. Specifications Frequency response Specified as the range where the magnitude response is above -3dB Example: 15Hz - 40 KHz Complex frequency response can also be specified using a Bode plot Example: http://www.linkwitzlab.com/images/graphics/p5.gif ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  12. Specifications Resonance Specified as the frequency where the peak magnitude response occurs. Resonance can be specified or read directly from a bode plot. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  13. Specifications Nominal Impedance • Since the impendence of the loudspeaker changes according to the input frequency, a nominal impedance is often specified. • This nominal impedance represents the minimum impedance across the input terminals. • Nominal impedance may be specified or derived from an impedance response plot. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  14. Specifications Nominal Impedance The nominal impedance of this loudspeaker is 4 ohms http://www.partsexpress.com/projectshowcase/dkhts/frntimp.jpg ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  15. Specifications Power Rating • Power ratings indicate how much power the loudspeaker can handle without damage. Power ratings can be specified in two ways: • RMS (or program) power • Peak power ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  16. Specifications Power Rating: Peak Power Peak power ratings indicate how much power the loudspeaker can handle for a very short time. Inexpensive louse speakers often only specify peak performance ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  17. Specifications Power Rating: RMS Power RMS power ratings indicate how much power the loudspeaker can handle continuously. It is the average power dissipated in the loudspeaker If RMS power rating is not specified, it can be estimated as being roughly half of the peak power capactiy ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  18. Specifications Sensitivity • Sensitivity ratings are specified as a dB sound pressure level output (SPL) for a given input power, measured a certain distance from the loudspeaker. • Sensitivity is usually specified as db SPL at 1 meter from the loudspeaker for a 1W input. • It is important to understand that a loudspeaker with a higher sensitivity will sound louder than a loudspeaker with a lower sensitivity at the same power rating! ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  19. Limitations • Limitations of loudspeakers • require high drive current when implemented using permanent magnet coils • performance usually optimized for the range of human hearing ( 20 Hz – 20 KHz ) • loudspeakers are directional due to the need of baffles to increase loudspeaker efficiency ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  20. Loudspeaker Systems Loudspeaker Systems To increase efficiency, loudspeakers are often used in multiple loudspeaker configurations. In these loudspeaker systems the individual loudspeaker components, and even the system enclosure, each contribute to the overall response of the system. Specifications may be given for the system itself rather than the individual components. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  21. Loudspeaker Systems Loudspeaker Systems: Components • Loudspeaker systems may contain the following components: • Subwoofer - for extra low frequency response ( below 500Hz ) • Woofer – for low frequency response ( below – 1.5KHz ) • Midrange – for mid frequency response ( 500Hz – 10KHz) • Tweeter – for high frequency response ( 1.5Khz – 20Khz) • Enclosure – often tuned for desired frequency response ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  22. Loudspeaker Systems Loudspeaker Systems: Components Passive filters (crossover networks) are often used in loudspeaker systems improve efficiency. These filters pass to each loudspeaker a signal tayored to its response ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  23. Loudspeakers Where to purchase loudspeakers • Individual loudspeakers may be purchased from online suppliers such as: • Parts Express - http://www.partsexpress.com/webpage.cfm?WebPage_ID=29 • Loudspeakers systems for professional use may be purchased from online retailers such as: • Sweetwater Sound - http://www.sweetwater.com/shop/live-sound/pa-speakers/ • Loudspeakers systems and home and mobile used can be purchased from online retailers such as: • Crutchfield – http://www.critchfield.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

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