Bandpass Enclosure
4th-order bandpass — two chamber volumes:
Sealed chamber: Vs (treats the driver as if in sealed box) Ported chamber: Vp (resonates at passband center)
Bandwidth (−3 dB points):
f_upper / f_lower = Q_bp² [approximately]
Peak frequency:
f_peak ≈ √(f_upper × f_lower)
Design equations:
The simplest approach for a 4th-order bandpass targeting a single frequency fâ‚€:
Vs = 0.7 × Vas
Vp = 1.5 to 2.5 × Vas
F_b_port = fâ‚€ (tune ported chamber to target frequency)
Then design ported chamber exactly as a ported enclosure (use Helmholtz formula above).
Illustration in preparation Description: Frequency response curves for 4th-order bandpass with three Vp/Vs ratios shown, demonstrating trade-off between bandwidth and peak efficiency