These DIY Desktop Speakers Are Designed with Transmission Line Theory in Mind

Have you ever wondered why some speakers cost $50 and others cost $5,000? Taking brand and marketing out of the equation, the difference comes down to the quality (and quantity) of drivers, the construction materials, and the time spent on perfecting the cabinet design. You can throw a decent driver in a simple MDF box, but you’re tossing the dice on whether it will sound good or not. That’s because sound waves bounce around inside the cabinet and resonate through it — sound doesn’t just come from the front of the driver. To optimize his 3D-printable desktop speaker cabinet design, Davide Ercolano took transmission line theory in account.

Transmission line theory describes how waves react with one another, and is most commonly calculated by engineers working with electromagnetic waves. But transmission line theory applies to sound waves, too. Noise-cancelling headphones, for example, utilize transmission line theory to generate sound waves that cancel out the unwanted sound waves around you. Carefully simulating how sound waves reflect and propagate inside of the speaker cabinet can also improve the sound quality of those speakers. That’s what Ercolano has done with his desktop speakers in order to achieve great fidelity, despite the cabinets being 3D-printed — something that is usually considered less than ideal.

Ercolano created the speaker cabinets by inputting his driver parameters into software called HornResp, which outputs an ideal transmission line. He then used that within Grasshopper for Rhino CAD to model the speaker cabinets. Those were then 3D-printed. As you can see, they look quite different than the basic box speaker cabinets you normally see. The unusual design lets the sound waves reflect through the cabinet in an manner that is optimal for sound quality. The drivers are powered by a YDA-138 Class D amplifier board. Input is either through an analog jack or through a CSR8675 Bluetooth module. Ercolano says the speakers can reach 10 watts RMS (Root Mean Square) without distortion — which is a lot for small desktop speakers of this seize — and reports that they sound fantastic. If you’re looking for a DIY, 3D-printable speaker design that actually sounds good, you’ll want to check these out.