Speaker Calculator

Lumped element calculation tool for loudspeaker design, made using Qt for Python.

Features

• Modelling of loudspeaker response in free-air and closed box.
  • SPL, electrical impedance, displacements, net forces
• Automatic calculation of most appropriate coil winding for given user parameters.
  • Wire properties are read from user editable "wire table.ods".
  • Possible to calculate for different types of wire section (round, flat, etc.)
• Includes a second degree of freedom to observe the effects on parent structure.
• Possible to manipulate graph settings and export curves.
• Calculation of magnet system mechanical clearances.
• Save/load of state.

Out of scope

• Nonlinearities in the system
• Calculation of magnetic flux
• Calculation of mass of speaker components (with the exception of the windings)
• Electrical inductance
• Change of acoustical impedance at higher frequencies

Screenshots

Installation

Windows only

Go to releases page to download the .msi installer. Run the installer and follow the steps in wizard. This will also associate the file extension .scf to this application.

Any Python environment

Using Python 3.12.*,

• Install the requirements for the application
  • pip install -r requirements.txt
• Run the application with python main.py

Tip

It is recommended to use a separate virtual environment for this application. venv and conda are popular options to create one, venv being part of Python standard library.

Manual

Tip

Most parameters in the application include a tooltip. Hover your mouse on the parameter for a few seconds to learn more about what a parameter does.

Underlying model

The application uses a linear model with 3 degrees of freedom to do the calculations. To see how the model is built, see function _build_symbolic_ss_model in electracoustical.py.

Important

The third degree of freedom which represents the vented port or passive radiator is not included in this version.

Coil windings

The application will give you coil winding options based on the winding height and the coil resistance you input as requirement. To be able to do this, a separate table that has information on different wire types needs to be provided by the user. This table is stored in wire table.ods which is located in subfolder data in the installation folder.

Tip

To see the location of wire table.ods in your computer go to Help -> Show paths of assets.. from within the application.

Wire table file content

This file contains Sheet1 which contains the following columns for each wire type.

• Unique name : Common name used to refer to this wire. Must be unique in this column.
• Type : Category for the wire
• Nominal size : Expected size of the conductor.
• Shape : Circular, square, rectangular etc.
• Average width; w_avg : This is the expected physical width including all the coatings and glues on the wire.
• Average height; h_avg : Similar to average width, but for height.
• Maximum width; w_max : This is the maximum expected physical width including all the coatings and glues on the wire.
• Resistance : Resistance per meter.
• Mass density : Mass per meter.
• Notes : User notes for convenience. Not used by the application.

Warning

The application is shipped with an incomplete wire table convenient for testing. User needs to change this to an accurate and complete wire table to be able to get good results. The top three rows of the spreadsheet contain title rows for import and they should not be modified.

Basic wire dimensions

Winding dimensions

For each layer, the average thickness of the wire w_avg is used to calculate a winding diameter passing through the center of the wire. This diameter is shown with Ø_li in image below.

In example A, stacking coefficient is chosen as 1.0 by the user. This means the wires do not mesh into the previous layer of winding. Total thickness of winding is simply 2 * w_avg.

In example B stacking coefficient is chosen as 0.8 by the user. This causes all the layers consecutive to the first layer to have a thickness of 0.8 * w_avg. Total thickness of winding becomes 1.8 * w_avg in this example. If there were three layers it would have become 2.6 * w_avg.

Note

For electricity related calculations such as winding length, the average dimensions defined in wire table (i.e. w_avg, h_avg) are considered.

Mechanical clearances

Note

For mechanical clearances and airgap sizes, the maximum dimensions defined in wire table (i.e. w_max) are considered.