ISSN:
1662-0356
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Natural Sciences in General
,
Technology
Notes:
Conventional loudspeaker membranes made of metal or synthetic material such as fabric, ceramicsor plastics suffer from nonlinearities and cone breakup modes at fairly low audio frequencies. Dueto their mass, inertia and limited mechanical stability the speaker membranes made of conventionalmaterials cannot follow the high frequency excitation of the actuating voice-coil. Low soundvelocity causes phase shift and sound pressure losses due to interference of adjacent parts of themembrane at audible frequencies.Therefore, loudspeaker engineers are searching for lightweight but extremely rigid materials todevelop speaker membranes whose cone resonances are well above the audible range. With itsextreme hardness, paired with low density and high velocity of sound, diamond is a highlypromising candidate for such applications.We report on the realization of dome shaped CVD diamond membranes by deposition on curvedsilicon substrates. Domes with diameters between 20 and 65 mm and with a thickness ranging from50 to 120 μm were prepared. After deposition, the substrate is dissolved and the rim of the diamonddome is cut by laser scribing. Free standing diamond membranes are mounted onto dynamic voicecoils and integrated into tweeter and/or midrange driver chassis. Extended tests and optimisationsled to loudspeaker systems that show a second and third harmonic distortion behaviour in theimportant frequency range between 3 to 10 kHz that is reduced by 40% in comparison to alreadyexcellent established values obtained with sapphire membranes. Cone resonance frequencies ofCVD diamond membranes are increased by a factor of two, as predicted by simulations
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/42/transtech_doi~10.4028%252Fwww.scientific.net%252FAST.48.142.pdf
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