SELTECH SOD20722X4CVT Manual de instrucciones
© 2020 SELTECH -All rights reserved
Recommended design guideline
for micro speakers
SELTECH –CONFIDENTIAL
© 2020 SELTECH -All rights reserved
2
Common Application Design Guidelines
Back volume
… why a closed back volume?
… how to connect to the speaker?
… mechanical robustness
… acoustical influence
Sound Port
… opening size vs. Bandwidth
… damping/acoustic load
… turbulence/noise
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3
Back volume
… to have a well defined acoustical environment behind the speaker
Well defined acoustical performance
… to be able to adjust the resonance frequency of the system
Resonance frequency range is the most efficient range of the speaker
… to avoid acoustical short circuit
Speaker for closed box design needed
… Why a closed back volume?
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4
Back volume
Using PCB as box-cover
Directly contacting to PCB
Create closed box
Contacting with flex-print
Create closed box
Contacting with contact pin
… How to connect to the speaker?
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5
Back volume
Create closed box
Contacting with contact spring
Reverse application
Directly contacting to PCB
… How to connect to the speaker?
back volume
Sound port at rear side of the speaker
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6
Back volume
Min. wall thickness to avoid wall resonating (depends on material)
Avoid « wall-to-wall-design » (e.g. antenna module)
Vibrations can cause rattling noise
Use « sandwich » for applying the speaker (foam-gasket, speaker, hard
support at rear side)
No heat-radiating components inside the back volume
Etc.
… Mechanical robustness
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7
Back volume
It is possible to put the RA completely down on a PCB or module housing
Venting to the back is provided by 4 venting holes and slits
All 4 holes should lead to a common, closed back volume
Back venting of RA11x15
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8
Back volume
Speaker surounded on three sides by walls will
influence resonance frequency and sensitivity.
Additional acoustic load will reduce performance
compared to a free scenario
Acoustic load at the rear side of speaker
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9
Back volume
Channels connecting parts of the
back volume can cause peaks in
frequency response
Shape of volume: high aspect ratio
volume spaces do not constitute
effective volume
Acoustical influence
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10
Back volume
Leaks can cause damage to the speaker by exceeding maximum membrane excursion
Acoustical influence
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1
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