Are you planning a specific build and need advice on geometry?
Martin J. King (often referred to simply as MJK in online audio communities like DIYAudio) approached loudspeaker design from a rigorous engineering perspective. Recognizing that classic acoustic textbooks by researchers like Leo Beranek provided the foundational theory but lacked accessible implementation tools, King mapped out the complex matrix mathematics governing acoustic wave propagation.
To build a speaker using King's methodology, designers typically navigate a structured engineering pipeline within the Mathcad environment: Driver Parameter Entry Users input standard Thiele-Small parameters ( Fscap F sub s Qtscap Q sub t s end-sub Vascap V sub a s Recap R sub e Blcap B sub l
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. martin j king mathcad worksheets
Instead of treating the air inside a box as a simple spring, King’s worksheets treat the enclosure as a transmission line or a waveguide. By applying one-dimensional wave equations and advanced matrix boundary conditions, his models accurately predict: Acoustic impedance transformations. Distributed mass and compliance of air columns.
If you are currently planning a custom enclosure build or trying to breathe life into legacy acoustic files, tell me:
King popularized the MLTL. By placing a specific-sized port at the end of a transmission line, designers could dramatically shorten the required cabinet length while retaining deep, controlled quarter-wave bass. Are you planning a specific build and need
The world of DIY audio and custom loudspeaker design owes a massive debt to Martin J. King. Long before accessible, modern simulation software existed, King revolutionized the way audiophiles design quarter-wave loudspeakers. Through his website, Quarter-Wave.com, he introduced a series of proprietary Mathcad worksheets. These sheets transformed complex acoustic physics into accessible engineering tools. They allowed hobbyists to accurately predict the performance of transmission lines, open baffles, and back-loaded horns. Who is Martin J. King?
The power of these worksheets lies in their accuracy and detailed output. 1. Accurate Transmission Line Design
King chose Mathcad because it allows for "live" mathematics. Unlike a static spreadsheet, Mathcad displays equations in standard notation, making it easier for users to follow the physics behind the results. This article promotes the fair use and historical
When calculated, the worksheets generate automated graphs displaying:
King extended his models to cover complex horn geometries. By treating a horn as a series of cascading quarter-wave sections, his sheets accurately predict the acoustic loading, efficiency gains, and impedance spikes of complex back-loaded horn enclosures. How the Worksheets Changed Speaker Building