2025 ASEE Annual Conference & Exposition

This “Bring Your Own Experiment” (BYOE) paper presents an innovative and unique multidisciplinary DIY speaker design project that helps develop first-year students’ understanding of the modelling, design, fabrication and experimental testing processes by taking them through the life cycle of a simple, engaging, low-cost physical engineering project. Students work collaboratively in teams of three, and on average we have had over 50 groups per semester.

This project was developed to introduce first-year students, all of which have not yet declared their major, to the interdisciplinary nature of engineering and expose them to aspects of both mechanical and electrical engineering, through exposure to the complex transformations of energy that occur in a speaker system.

From the mechanical engineering side, students learn computer-aided design (CAD) techniques to draw, fabricate and assemble a mid-range audio driver and speaker enclosure. From the electrical engineering side, students learn simple passive and active filters (at a functional depth) to implement and test such circuits on a prototype breadboard. Students design and implement an analog audio equalizer and crossover network for a two-way speaker system consisting of their DIY midrange driver and a commercial off-the-shelf (OTS) tweeter.

Bridging the electrical and mechanical aspects of the project, students learn the importance of experimental measurements by testing their constructed speaker inside the two-way enclosure situated in a sound-isolation box, using a measurement microphone and free audio software (Room Equalizer Wizard). Students characterize the frequency response of their DIY midrange driver and the OTS tweeter and use this to: (a) determine appropriate parameters for a two-way crossover circuit, (b) design a high-pass filter to remove the very low frequencies their midrange driver cannot handle, and (c) help decide cutoff frequencies for their equalizer.

This design project has considered a few different permutations over the three semesters it has been running. The first iteration used laser-cut MDF for the speaker enclosure and 3D-printed parts for the speaker driver. However, this placed intense demand on our maker space’s 3D-printers and a redesign was needed. In the next offering, we shifted to an approach where students laser cut MDF parts that fit together to form the midrange driver’s chassis and spider. Students were still able to make a 3D-printed chassis if they wished, but this was optional.

This paper serves as a guide to help instructors integrate a DIY speaker design project into an existing or new multidisciplinary engineering project course for first or second-year students. It provides detailed documentation of how the prototype speaker system was designed, constructed, and adapted over time for the classroom. An itemized list of materials and required systems (e.g., 3D printing, laser cutter, etc.) is provided, as well as a discussion of the problems that were faced and how they were solved. The entire speaker system, including multiple midrange driver examples and the experimental setup with sound-isolation box, will be demonstrated at the ASEE conference.