Martin J. King is, by his own account, a long-time enthusiast of transmission line loudspeakers. For years, he was frustrated by the lack of a reliable, proven mathematical model for these complex enclosures. Designing a TL speaker was often described as more of a "black art" or a "hit-and-miss" affair, heavily reliant on guesswork and luck. Determined to bring scientific rigor to the process, King decided to develop his own model using the Mathcad computer program, a decision that would ultimately define his legacy and change the hobby forever.
Using a Martin J. King worksheet is a unique experience. Upon opening a file, the user is greeted by pages of algebraic derivations. There are no "Next" buttons or 3D renderings.
A massively powerful, free loudspeaker simulation software that has evolved to handle TLs, MLTLs, horns, and multi-driver configurations seamlessly. martin j king mathcad worksheets
Users could precisely position the driver and the port at any point along the length of the line. King demonstrated that placing a driver at specific geometric nodes (like 1/3 or 1/5 of the way down the line) could naturally cancel out nasty harmonic peaks, minimizing the need for heavy stuffing.
The story of the worksheets begins with a fundamental problem. Prior to the 2000s, designing a transmission line speaker was frustratingly unpredictable. Enclosure sizes, line lengths, and damping levels were often chosen based on trial and error, frequently leading to designs with poor frequency response and "one-note" bass. Martin J
The sheets typically require older versions of Mathcad (often version 8 or 11) to run, which can make them difficult to use on modern operating systems without emulation.
Martin J. King originally hosted his research and files on his dedicated site, Quarter-Wave.com . Over time, changes in internet hosting, the licensing model of PTC Mathcad, and King's personal retirement led to the formal withdrawal of the sheets from direct public distribution. Designing a TL speaker was often described as
How to use Martin J. King's software to design a TL ... - diyAudio
The Transmission Line (TL) worksheets allowed designers to finally predict the impact of line length, cross-sectional area changes (tapering), and driver placement within the line. This is crucial for designing modern, high-performance TL speakers. 2. Open Baffle (OB) Simulation
Before MJK, transmission lines were deemed an unpredictable "black art." Today, thanks to his pioneering mathematics, quarter-wave design is an exact science. Whether you manage to run his original Mathcad files or use modern software inspired by his papers, you are directly benefiting from the foundation laid by Martin J. King.
Martin J. King is a retired engineer who applied his professional background in mechanical and acoustic engineering to the field of loudspeaker design. Unlike many commercial software developers who create "black box" programs—where the user inputs data and receives a result without seeing the internal logic—King took a different approach.