DIY Audio Wiki / Midwest Audio Club

The Diffraction and Boundary Simulator is a loudspeaker baffle diffraction and room boundary reinforcement tool that uses MS Excel. It contains two different sections:

The first section calculates the baffle edge diffractions and baffle step using the Vanderkooy model for edge diffraction. However, I expanded the basic Vanderkooy math to include several additional design functions. Although limited to 4-sided baffles with a single driver, the results are extremely accurate based on measurements that have been performed. The additional features include the ability to set the mic / listening distance and vertical and horizontal off-axis angle to any distance or angle desired in the front hemisphere of the speaker and the diffraction will be calculated to this mic position. The user may also enter any value desired for edge radius and speaker piston diameter and the edge averaging and directivity will be factored into the diffractions results. The diffraction model also includes an open baffle mode that will simulate open or dipole baffles with their associated roll-off based on the mic distance entered.

The second section uses the Allison room boundary reinforcement equations that calculate the amount of acoustic reinforcement a speaker gains based on its proximity to the floor, the side wall, and the wall behind the speaker. In addition room gain with leakage can be modeled to simulate room pressurization gain.

Finally, there is a choice of various combinations of the simulations described that can be saved as .frd files and imported into other software like my Woofer Box and Circuit Designer or my Frequency Response Modeler so that room and baffle response can be included with other frequency response data.

The file requires Excel 2000 or higher with Service Pack 1 and 2 installed and must have the Analysis Toolpak and Analysis Toolpak VBA installed in the add-ins, and security must be set to allow running of macros.

• Baffle Diffraction and Boundary Simulator 1.10 Update Info: Changed boundary gain from power calculation to SPL, and added rear wall cancellation when in dipole mode.
• Baffle Diffraction and Boundary Simulator 1.20 Update Info: Correct error in wall distance calculation. Added toggle between power response an axial response for the boundary reinforcement
• Baffle Diffraction and Boundary Simulator 1.30 Update Info: Improved Compatibility with recent versions of Excel

Spreadsheet (and all previous versions), its VBA Modules, and its file structure - © Copyright 2020 Jeff Bagby - File Design, Structure, Mathematics, and selected VBA routines

File is Free for personal DIY Speaker Design use. Commercial use is prohibited without prior authorization of the author

• diffraction_boundary_simulator_1.30.xlsm.zip