Inside the Build: Technical Deep Dive into Kerry’s End-Game Speakers

Building a speaker from scratch is never just about wood and wires—it’s about engineering sound through modeling, measurement, and iteration. Kerry’s latest floor-standing speaker build here at CSS is a perfect example of that process. What began as a relatively straightforward cabinet project evolved into a deeply technical exercise in crossover design, acoustic optimization, and system integration. Let’s walk through the technical choices, refinements, and solutions that defined the build, hopefully offering some inspiration and insight for your next project.

The build began, as well-planned speaker projects do, with box modeling to determine the ideal internal volume. Kerry had already worked with the chosen woofer in previous builds and knew it performed well in about 0.75 cubic feet. With six woofers per speaker, that meant 4.5 cubic feet of internal volume—substantial enough to warrant a modular approach. Instead of building a single monolithic enclosure, he divided the cabinet into three stackable sections: two bass modules housing three woofers each, and a separate mid/tweeter module. This allowed for easier transport and cleaner wiring, while maintaining structural integrity.

Port tuning was calculated around 32 Hz using a 3-inch port at 14.1 cm length, offering a flat modeled response. However, Kerry opted to tune slightly lower to shift the peak in vent velocity down the frequency range. While this increased F3 slightly, it minimized the potential for chuffing in real-world listening, especially since musical content in that region is typically minimal. Each bass module was tuned and modeled independently, reinforcing the modular design logic.

The cabinet design included internal bracing and angled front baffles for both structural and visual refinement. With that solid foundation in place, Kerry then turned to measurement and crossover design. This is where the build took on greater complexity. The first obstacle came when the tweeter and midrange drivers, though individually well-behaved, didn’t overlap as cleanly as expected. The midrange rolled off around 1.6 kHz, and the tweeter didn’t quite extend low enough to cover the gap comfortably. Kerry explored off-axis behavior to see if the issue was localized to only a single axis, something that can happen with a diffraction artifact, but found it persisted across angles, meaning he would have to cross below this point to achieve an effective crossover.

Crossover development was where Kerry applied the bulk of his technical focus. Starting with a third-order high-pass filter on the tweeter and flexible resistor positioning, he explored different slopes and component values to achieve the desired acoustic response. Waveguide loading on the tweeter introduced a downward-sloping response, which he began to compensate for with a small 2.2 μF capacitor. While this helped flatten the top end, it introduced a peak around 3 kHz and didn’t completely bridge the gap with the midrange. After testing a wide range of combinations, he began incorporating notch filters—ultimately leading to a refined and balanced result.

The final crossover was thoughtfully constructed: a third-order tweeter network with two notch filters, a midrange with second-order low-pass and fourth-order high-pass sections plus two more notches, and a woofer circuit using a simple second-order electrical filter. A measured dip near 2 kHz was left intentionally to avoid over-energizing the room in the off axis and creating excessive forwardness. Listening tests confirmed that this choice led to a smoother, more natural sound.

During voicing and evaluation, Kerry took a methodical approach to testing and fine-tuning. He used Wago connectors to iterate quickly and tested the system over several days. A discrepancy between expected and actual output led him to re-check the crossover assembly, where he discovered that one capacitor had been temporarily pulled during prototyping. This small oversight highlighted the importance of verifying each stage against the model—and once corrected, the measured results snapped back into alignment.

In the end, this speaker wasn’t built for mass production or to check a box—it was built for the experience. Kerry wanted to explore new techniques, challenge himself with crossover topology, and revisit the joy of building just for the sake of it. And the result reflects that intent- check them out here. With broad imaging, controlled tonality, and the ability to play effortlessly at high volume, the finished system represents a full-circle achievement: a technically complex speaker with meaning behind every design choice. He calls them his “endgame” speakers, and it's not hard to see why.

Ready to Build Your Own?

If this build has sparked your curiosity or reignited your love for DIY, there’s no better time to dive in. Whether you’re replicating Kerry’s floor stander or adapting these principles into your own design, the process is where the value lies. Engineering sound is rarely linear—and that’s what makes it so rewarding. If you have questions about modeling, crossovers, or cabinet design, drop them in the comments or reach out directly at info@css-audio.com. We’re always geeked to help fellow builders!