ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: LoudspeakersOutlineReference listTo explore further (survival pointers of web references etc)Major applicationsBasic working principle illustratedDesign Classification – Dynamic LSDesign ClassificationSlide 9Major SpecificationsSlide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Sample ConfigurationSlide 19How/Where to PurchaseECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Assignment#01: Literature Survey on Sensors and Actuators Topic: LoudspeakersPrepared by:Balaji RavindranDept. of Electrical and Computer Engineering Utah State University3/7/20083/7/2008ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-2Outline –Reference list–To probe further–Major applications–Basic working principle illustrated–Design Classifications–Major specifications–A typical sample configuration in application (application notes)–How/Where to Purchase01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-3Reference list•http://hyperphysics.phy-astr.gsu.edu/hbase/audio/spk.html#c1•http://melhuish.org/audio/theory.html•http://en.wikipedia.org/wiki/Loudspeaker#Full_range_drivers•http://www.trueaudio.com/st_diff1.htm•http://www.teamrocs.com/technical/pages/vented_enclosures.htm•http://www.silcom.com/~aludwig/Loudspeaker_construction.html01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-4To explore further (survival pointers of web references etc) •http://history.sandiego.edu/GEN/recording/loudspeaker.html•http://en.wikipedia.org/wiki/Woofer•www.bolo-digital.com/pages/surround/surround.html•http://bdsays.files.wordpress.com/2007/02/rahman_control.jpg•http://www.sweetwater.com/•http://www.mcsquared.com/speakers1.htm01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-5Major applications •Recording Studios / Home Theatre,•Telephones / Mobile / Voice Communication,•Hearing Aids,•Motion Pictures•University / Public / Private Conferences•Computers•Space Applications•Medical ApplicationsBasic working principle illustrated•Electromechanical transducer–Electrical signal to Sound•History–Siemens - nonmagnetic parchment diaphragm as the sound radiator of a moving-coil transducer, loudspeaker horn that would be used on most phonographs players in the acoustic era01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-6Design Classification – Dynamic LS01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-7Design Classification•Horn Loudspeakers–Oldest Loudspeakers–Shaped waveguide – to increase directivity and transform small diameter high pressure to large diameter low pressure at the mouth of horn–A horn loaded speaker can have a sensitivity as high as 110 dB @ 2.83volts–Majorly used during WWII era01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-8Design Classification•Piezo-Electric Loudspeakers–Resistant to overloads–inherently capacitive electrical load–Disadvantage•amplifiers can oscillate when driving capacitive loads, which results in distortion or damage to the amplifier–Piezoelectric speakers can have extended high frequency output–Used in watches(beeps) or in computers01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-9Major Specifications•Speaker or Driver type–Full Range Driver•Center Cap – normal cone with dome center cap•Whizzer cone – 1 large cone and 1 small whizzer cone•Figure – Axiom 180 LS•High efficiency, low excursion, and a frequency response graph that shows lowered sound pressure levels at medium to low bass•Low efficiency one’s have flatter frequency response.01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-10Major Specifications•Woofer–useful for augmenting main loudspeakers by providing playback of low bass frequencies at high levels–Electro-dynamic Driver•These use a cone, driven by a voice coil surrounded by a magnetic field. The voice coil and magnet form a linear electric motor•When current flows through the voice coil, the coil moves in relation to the frame according to Fleming's left hand rule, causing the coil to push or pull on the driver cone in a piston-like way. The voice coil is attached by adhesives to the back of the speaker cone. The resulting motion of the cone creates sound waves as it moves in and out01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-11Major Specifications•Rated Power–peak power a loudspeaker can handle before thermally destroying the loudspeaker–A driver may be damaged at much less than its rated power if driven past its mechanical limits at lower frequencies.•Sensitivity–The sound pressure level produced by a loudspeaker, (in dB), measured at 1 meter with an input of 1 watt01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-12Major Specifications•Impedance–typically 4 Ω (ohms), 8 Ω,•Frequency Response–The measured, or specified, output over a specified range of frequencies for a constant input level varied across those frequencies(usually +/- 2.5dB)01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-13Major Specifications•Enclosure types–cabinet designed to transmit sound to the listener via mounted loudspeaker drive units.–prevent the out of phase sound waves from the rear of the speaker from combining with the in-phase sound waves from the front of the speaker–Major problem - Diffraction Loss and Compensation•occurs in the low frequency range of loudspeakers in enclosures that are located in the open, away from walls or other surfaces•Because the "energy density" at low frequencies is reduced there is a loss of bass – (Figure – 6dB Step Reduction Ckt)01/14/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-14Major Specifications•Enclosure types–Vented Enclosure•"bass-reflex" enclosures require special construction due to the large forces that can be developed by the drivers installed inside that act on them.•Two Primary Functions–the separation of vibrations from the front and rear of the loudspeakers,–containment of air so that the air can act as a resonating elastic medium inside the
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