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
King chose Mathcad because of its ability to handle complex matrix algebra and differential equations while displaying them in a readable, "whiteboard" format. This transparency allowed users to see the physics at work, rather than just interacting with a "black box" software program. The worksheets calculate the complex impedance and pressure at both the driver and the terminal (port), then sum them to show the final acoustic output. Impact on Audio Design martin j king mathcad worksheets
While Martin J. King has retired and no longer updates the original Mathcad files, his models remain the "gold standard" for quarter-wave theory. Many of his equations have since been ported into modern software like Leonard Audio’s Transmission Line software or AkAbak, ensuring his contributions continue to influence speaker building today. Martin J
: Incorporates Thiele/Small parameters, crossover networks (passive or active), and compensation circuits like Zobel or L-pads. Quarter-Wave.com Quarter Wavelength Loudspeaker Design Software Obsolescence: Old Mathcad files (Version 11, 13,
The math said it would work.
This is the holy grail. This worksheet allows you to model a straight, tapered, or expanding transmission line. Input parameters include:
Here are some tips and tricks for using Mathcad worksheets effectively: