Lumped Speaker Boundary

The condition is used to model a loudspeaker (dust cap, cone, surround assembly, and motor) or another transducer using a lumped representation with a coupling to an interface. The mechanical and electric properties of the speaker can, for example, be described through a Thiele-Small parameter representation and associated lumped parameters.

In the time domain, nonlinear effects can be included in the lumped model through parameters that depend on the axial position x or velocity v of the speaker. These are, for example, the typically measured BL(x), CMS(x), or RMS(v). Predefined variables exist for the axial velocity actd.lsb1.v_ax and an ODE is solved for the associated axial position actd.lsb1.x_ax (use the appropriate physics and feature tag). These variables can be directly used in expressions in the electric components in the model as they are globally defined.

The properties of a back volume can also be modeled using a lumped representation through either a simple equivalent acoustic compliance or a more general RCL circuit representation. On the other hand, if the air domains on both sides of the speaker are modeled explicitly (included in the model) then there are two possible setups:

If the speaker diaphragm is represented by a domain (a “solid” with air domains on both sides); then use two features, one applied to the upper side and one to the lower side. Make sure the speaker axis is the same on both sides and that the back volume correction is disabled (the option). Finally, in the add two nodes in series, when setting up the coupling.

For microtransducer applications it may be necessary to use the Lumped Speaker Boundary or Interior Lumped Speaker Boundary of The Thermoviscous Acoustics, Transient Interface.

	Lumped Loudspeaker Driver Transient Analysis with Nonlinear Large-Signal Parameters: Application Library path Acoustics_Module/Electroacoustic_Transducers/lumped_loudspeaker_driver_transient

Define how the (projected) of the speaker is computed by selecting either (the default) if all boundaries are present, or if the speaker surface is only partially represented.

When is selected, select the Ascale as (the default, the model is analyzed for the presence of symmetry conditions); or and enter a value (default is 1). The settings are required in order to compute the effective area of the speaker which is used to compute the acoustic load and radiated power.

Define the eax by selecting (the default) or . For the automatic option, the axis is computed as the average of the surface normals; this option is valid if a full speaker surface is selected. The option should be used if the speaker surface is only partially represented and is the only option when is selected.

The does not model the acoustics on the back side of the speaker cone explicitly. The properties can be entered either through a volume giving a simple compliance effect, through a simple RCL model, or through a user defined acoustic impedance of the back volume.

Select the as (the default), , or .

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For the enter a Vback (SI unit: m3). The volume represents an acoustic compliance Vback/(ρc2).

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For enter the values of the equivalent acoustic resistance Rac (SI unit: kg/(m4·s)), compliance Cac (SI unit: m4·s2/kg), and inertance Lac (SI unit: kg/m4).

When the and the options are selected an ODE is solved relating force acting on the cone Fc and axial velocity vax. For the general RCL option

where SD is the (projected) speaker area.

Enter the initial value of the force Fc and axial speaker position xax, used when solving the associated ODEs. The default value is 0 for both and is typically correct, except if the simulation is started, for example, with an initial excursion of the driver.

This section gives information about the state of coupling/connection to an Electrical Circuit interface. If the is not connected, the text text will be displayed. Once connected, a reference with a tag to the associated node, in the Electrical Circuit interface, is displayed.