The Physics of Headphone Distortion
Your headphones contain small drivers — essentially tiny speakers. These drivers have physical limits. When pushed beyond their mechanical capabilities, they produce unwanted sounds: rattle, breakup, and distortion.
Why Test Your Headphones?
Detecting driver issues early can save your headphones from permanent damage. Common causes of rattle include: loose driver mounts, damaged surround materials, misaligned voice coils, or simply pushing the driver beyond its Xmax (maximum excursion).
Chapter 1: Understanding Driver Limits
Each headphone driver has a Thiele-Small parameter set that defines its physical limits:
- Xmax (Maximum Linear Excursion): How far the driver can move linearly before distortion
- Fs (Resonance Frequency): Where the driver naturally oscillates most easily
- Re (DC Resistance): The electrical resistance of the voice coil
Chapter 2: What Each Test Reveals
Frequency Sweep
Plays frequencies from 20Hz to 20kHz. Rattle typically appears at specific resonant frequencies where the driver is under maximum stress — often in the bass region (40-150Hz) or at high frequencies where the tweeter is struggling.
Impulse Test
A sharp transient (like a drum hit) tests the driver's ability to start and stop quickly. Poor impulse response reveals lazy bass, overhang, or mechanical looseness.
Pink Noise
Random noise containing all frequencies equally. Pink noise tests sustained power handling and reveals any frequencies where the driver is uncomfortable.
Chapter 3: Common Rattle Locations
- Driver surround: The flexible ring around the cone
- Voice coil former: Collisions with the magnet
- Grille mesh: Physical contact with protective covers
- Internal wiring: Loose wires touching driver components
The Volume Sweet Spot
The "rattle threshold" varies with volume. Test at your typical listening level, then increase 25% to find the safety margin. If rattle appears below your normal volume, you may have a defective unit or need an EQ adjustment.
Know Your Cans
Every headphone has limits. Test yours to understand its capabilities and avoid pushing it past its breaking point.
Run Test