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| Transducer
Modeling |
| Conventional
transducer modeling has been around for over 50 years. This type of
modeling describes the transducer using a simplified set of fixed
constants. In many cases complex parameters were assumed to be negligible,
or have fixed constant values, to allow for a simplified approximate
solution. While this approach was very appropriate decades earlier,
and actually demanded due to the limitations of hand calculation,
modern computer computational abilities allow for much more detailed
and advanced analysis to be performed. |
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of the acoustic pressure diffracting around an enclosure has its origin
in the 90 degree off-axis response of the transducer. Errors in the simulated
off-axis behavior can produce errors in the entire simulated field around
an enclosure. This is especially significant for the response at the sides
and rear of an enclosure, where all sound arrives solely from diffraction.
Therefore, realistic diffraction analysis demands that realistic models
be utilized for the directional behavior of the transducers. |
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| Two
parameters Shape and Profile are used by the transducer models of EnclosureShop
to determine the essential high frequency characteristics for the transducer.
They directly control radiation impedance, directivity, and off-axis response
for the transducer. These parameters greatly affect the diffraction modeling
of enclosures. |
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Diaphragm Profile
There are three possible profiles available for use as shown here.
Flat profile is sometimes needed for ribbon tweeters and possibly
other special devices, but the Cone and Dome profiles are common.
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Diaphragm Shape
In order to simulate the behavior of all possible structural variations
in a generalized fashion, a methodology of small source arrays was
developed. The small sources embody their own directional characteristics.
Additional transfer functions are applied to the array elements which
enable a wide variety of directional characteristics to be emulated.
Each transducer is modeled by a group of sources arranged in the required
geometry as shown in the drawings here. Between two and three dozen
array elements are used in each shape model. These sources are driven
by a suitable group of transfer functions as dictated by the shape
and profile parameters. |
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Transducer Parameters
The transducer modeling capabilities contained in EnclosureShop are considerably
more detailed then past conventional methods. In fact EnclosureShop supports
three different transducer models: STD, TSL, LTD. The standard model STD
uses a minimal set of legacy parameters. The TSL model is a continuation
from LEAP-4, and the new LTD model in LEAP-5 adds numerous parameters for
highly accurate simulation across a large dynamic range. |
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