Driver Excursion, Displacement, And Large-Signal Limits
Large-signal measurement shows how the driver changes as it moves and heats; one published excursion number cannot describe the whole operating envelope.
Separate the limits
| Term | Question |
|---|---|
| geometric Xmax | what geometry-based travel criterion was used? |
| performance Xmax | where do distortion or parameter changes reach a declared threshold? |
| Xmech | what physical clearance or damage boundary exists? |
| application limit | what excursion is acceptable in this enclosure, filter, voltage, and duty cycle? |
Measure displacement carefully
Use a laser, displacement sensor, validated model, or other suitable method. Record calibration, target, axis, cone point, bandwidth, rocking sensitivity, and whether cone deformation differs from voice-coil motion.
Nonlinear parameters
Bl(x), Kms(x), Le(x), dynamic DC offset, asymmetry, thermal resistance change, and suspension memory help explain compression and distortion. Interpret only parameters that the measurement can identify reliably.
Application context
Free air, sealed, vented, bandpass, passive-radiator, and installed vehicle systems produce different displacement-versus-frequency behaviour. Include the actual filters and protection.
Build the envelope
Save terminal voltage, current, displacement, distortion, compression, temperature, mechanical noise, and first limiting mechanism versus frequency and time.