Martin J. King is a name synonymous with high-end loudspeaker design and the democratization of advanced acoustic modeling. For over two decades, his "Quarter Wavelength" Mathcad worksheets have served as the gold standard for DIY enthusiasts and professional engineers alike. These tools bridged the gap between basic "Thiele/Small" calculations and the complex physical realities of transmission lines, back-loaded horns, and open-baffle systems. The Legacy of the Quarter Wavelength Theory

Martin J. King’s Mathcad worksheets are the gold standard for designing transmission line (TL) and quarter-wave loudspeaker enclosures. They allow you to accurately model complex behaviors like damping, baffle step response, and driver positioning before you ever touch a saw. 1. Getting the Software

Disclaimer: Martin J. King retains all copyrights to his worksheets. This article promotes the fair use and historical preservation of his work for non-commercial educational purposes.

The most famous product of King’s work is the "King Audio Project" (KAPO) and the widespread adoption of specific transmission line geometries that he validated. Enthusiasts on forums such as DIYAudio and the now-defunct Quarter-Wave Yahoo Group have spent thousands of hours dissecting his spreadsheets.

The benefits of using Martin J. King's Mathcad worksheets include: