Punk science, loudspeaker breakdown, fun kid projects, and a father-and-son story.

» In Volume 31’s “Sound-O-Light Speakers” project (, two diagrams on page 82 describe an acoustic suspension (sealed) alignment and a bass reflex (vented) alignment. Unfortunately, the description of the bass reflex design is based on a popular but incorrect theory — that the back wave of the driver is made available via a port or opening to augment the sound from the front of the driver.

In reality, the port is a Helmholtz resonator whose resonance is defined by its length and cross-sectional area. The port is typically tuned to a frequency that’s lower than that of the driver — it’s not a manifestation of the back ...

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