Worksheets: Martin J King Mathcad

Open baffle speakers dispense with boxes entirely, relying on a flat panel. King’s OB worksheets model the acoustic short-circuit that happens when the front and rear waves meet. By simulating room boundaries and baffle geometry, designers can calculate exactly how much bass boost or equalization is needed to achieve a flat response. Key Benefits of Using MJK Worksheets

Martin J. King’s Mathcad worksheets are a legendary, free (donation-ware) suite of simulation tools for : transmission lines (TLs), tapered lines, mass-loaded TLs (ML-TL), horn-loaded lines, and open-baffle designs. Unlike simplified box-modeling software (e.g., WinISD), MJK solves 1D acoustic wave equations inside a line with damping material, making it the gold standard for DIY TL design.

Define how many ounces per cubic foot of damping material you plan to use, and where it will be placed in the line.

Martin J. King is not a commercial software developer, but a professional engineer who uses Mathcad daily in his day job. For him, the development of his models was a labor of love. Dissatisfied with the lack of a proven mathematical model for quarter-wavelength enclosures (Transmission Lines, TQWT, and Horns), he began developing his own simulations about 15 years before the launch of his website, "Quarter Wavelength Loudspeaker Design". martin j king mathcad worksheets

Historically, users could run these on the (a free viewer) or Mathcad 2000 Professional . However, as operating systems and software evolved (such as Mathcad Prime and 64-bit Windows), users often encountered compatibility hurdles. The community found that older versions (like Mathcad 14 or earlier) tend to be the most stable for running MJK's legacy models, though they can be difficult to install on modern PCs.

These sheets model complex horn profiles used to maximize the efficiency of full-range drivers. They map the transition from a narrow throat at the driver's rear to a wide mouth, optimizing acoustic coupling with the room. Technical Advantages Over Standard Design Software Standard DIY Software M.J. King Mathcad Worksheets Lumped element (simplified) One-dimensional wave equations Stuffing Simulation Global density approximation Location-specific fiber density scaling Driver Placement Fixed at the terminal end Variable position along the acoustic line Geometry Support Rectangular boxes / simple ports Tapered, expanding, or irregular lines Step-by-Step Workflow: Using the Worksheets

The effectiveness of these worksheets is best demonstrated by their commercial adoption. In 2017, EJ Jordan (a famous driver manufacturer) released the , a speaker specifically designed for the Eikona 2 driver. Open baffle speakers dispense with boxes entirely, relying

Instead of a generic CAD program, these worksheets are specialized simulations that:

Unlike traditional sealed or ported enclosures—which rely heavily on Thiele-Small parameters simplified into lumped-element models—quarter-wave speakers treat the air column inside the cabinet as a transmission line or pipe. King took classical acoustic equations, refined them with real-world empirical data, and coded them into Mathcad. Why Mathcad?

While King developed several sheets over the years, a few became foundational tools for the DIY audio community. 1. The Transmission Line Sheets (Transmission Line.mcd) Key Benefits of Using MJK Worksheets Martin J

At their core, the worksheets are sophisticated written in the Mathcad programming language. They allow a user to input the Thiele/Small parameters of a specific driver, along with the physical dimensions and taper of a proposed enclosure, to predict the acoustic output, impedance curve, and cone displacement.

King took complex acoustic equations—specifically Navier-Stokes equations and boundary tier physics—and applied them directly to loudspeaker enclosures. He proved that transmission lines, open baffles, and back-loaded horns all share underlying quarter-wave physics. To make this math accessible to the DIY community, he packaged his equations into user-friendly Mathcad worksheets. Why Mathcad Worksheets?