There's a sound that every levitation engineer dreads. It's a high-pitched whine — somewhere between a mosquito and an old CRT television. It comes from the coil. Specifically, it comes from the magnetic core of the coil vibrating under the PWM current that drives the levitation field. If that vibration falls into the 1-20kHz range, and if the mechanical structure of the base happens to form an efficient acoustic radiator (like a speaker cone), you get an audible buzz that drives people crazy.
This is not a rare problem. It's universal in electromagnetically-driven devices. Computer power supplies do it. LED dimmers do it. Cheap levitating lamps do it especially loudly because their coils are physically small, tightly wound, and mounted inside a resonant plastic housing that amplifies the sound. If you've ever bought a $20 levitating gadget on Amazon and returned it because of the "whining noise," this is what you were hearing.
Our solution has two layers. The first is frequency-domain. Instead of driving the coil with a fixed-frequency PWM signal centered around 10-15kHz (right in the sweet spot of human hearing), we use spread-spectrum modulation with a center frequency above 25kHz. Human hearing drops off sharply above 20kHz — most adults can't hear anything above 16-17kHz. By shifting the fundamental switching frequency well above the audible range, the primary vibration mode of the coil is literally inaudible regardless of coil construction or housing acoustics.
The second layer is mechanical. We vacuum-impregnate every coil with epoxy resin. This fills the microscopic air gaps between copper windings that would otherwise act as tiny vibration cavities. Once cured, the coil becomes a solid block — it can still generate magnetic fields (that's the whole point), but it cannot mechanically vibrate at audible frequencies because there are no internal voids for the vibration to propagate through. We measure acoustic noise on every production batch using a calibrated microphone in an anechoic chamber. Our standard is under 20dB at one meter — quieter than a whisper.
This is a detail that most levitating product manufacturers either ignore or compensate for by adding foam padding (which works for about three months before the foam compresses and the noise returns). For hotel levitating moon lamps, bedroom floating night lights, and office levitating desk lamps — applications where the product runs continuously in a quiet environment — the noise spec is just as important as the brightness spec.
Every GLEAGLE magnetic levitation product ships with this noise treatment. It's not a premium feature. It's a baseline requirement. Because a levitating lamp that buzzes isn't magic — it's annoying.