Advanced magnet system design for moving coil drivers & micro speakers

The magnet system is the heart of every headphone driver and micro speaker, it’s what converts electrical current in the voice coil into the mechanical force that moves the diaphragm and creates sound. Get the design right, and the payoff shows up directly in battery life, power efficiency, and audio quality. Get it wrong, and no amount of downstream tuning will fully make up for it.

In our latest white paper, we take a closer look at what goes into designing a high-performance magnet system for portable audio components.

We cover why neodymium magnets have become the standard choice over ferrite, Alnico, and Samarium Cobalt, and what the trade-offs are between magnet grade and temperature stability. We explain the role soft iron yokes play in directing and concentrating the magnetic field through the air gap and when it makes sense to move to higher-saturation alloys like Vacoflux 50 despite the added cost.

The paper also digs into the performance parameters that a magnet system design directly influences: how tightening the air gap tolerance increases magnetic field strength, why that improves the Qes factor and overall power efficiency, and how all of this ties back to something every product team cares about – operating time before the next charge.

Finally, we walk through how we use Comsol simulation to optimize magnet height, diameter and grade, yoke thickness and diameter, and voice coil position, running through iterations automatically to land on the strongest and most linear Bl curve possible.
As a real-world example, we share simulation results from our OWR-4009T-36NF headphone driver, including flux density mapping and Bl-versus-displacement data.

If you’re working on earphones, headphones, or micro speakers and want to understand what really drives performance-to-size ratio in these components, this white paper is worth your time.

Download WP16: Advanced magnet system design technology for moving coil drivers & micro speakers below.