Bandpass And Multi-Chamber Enclosure Alignment
Canonical Definition
A bandpass alignment acoustically filters one or both sides of the driver with chambers and ports. Its passband, ripple, group delay, excursion, heat, port flow, and out-of-band behavior come from the complete coupled system—not the order number or one chamber tuning alone.
Common Topologies
| Topology | Rear side | Front side | Main design burden |
|---|---|---|---|
| Fourth order | sealed chamber | vented chamber | passband balance, hidden excursion and heat |
| Sixth order | vented chamber | vented chamber | coupled tunings, two port-flow limits, high sensitivity to losses |
| Other multi-chamber systems | system specific | system specific | complete acoustic network and measurement |
Not Two Independent Boxes
In a sixth-order system, both chambers act on the same moving system. Changing one volume, vent, loss, or leak changes the entire response and excursion distribution. The hidden driver can be thermally or mechanically overloaded while port output still appears strong.
Model Contract
- Every chamber's true net air volume
- Every port's area, effective length, flare, bend, boundary, and solid displacement
- Driver small- and large-signal state
- Leakage, damping, and port-loss assumptions
- Driver excursion, both port flows, compression, group delay, and voltage
- Vehicle transfer and any window, hatch, or removable opening state
Verification
- Measure low-level impedance and each port near field.
- Check chamber leaks, panel vibration, and physical dimensions.
- Track driver temperature, resistance rise, distortion, and compression as level increases.
- Verify both port outputs and tuning shifts.
- Measure the installed passband at the intended seats and vehicle states.
Vehicle Openings Are Not Free Extra Chambers
A window, hatch, or cabin opening can create a new acoustic condition, but it is not a fixed third chamber or port without measured geometry, boundary conditions, transfer response, and repeatability. Secure any insert and preserve occupant safety.