ABSTRACT
Figure 15.1e shows a 3rd + 3rd order bandpass subwoofer. Now both the front and rear chambers are tuned by ports. As for a straightforward ported subwoofer, power handling is poor at frequencies below the passband due to lack of loading on the rear of the drive unit cone. The transient performance of a 3rd + 3rd order bandpass subwoofer is usually inferior to either sealed, ported or 2nd + 2nd order bandpass systems, so this type of bandpass subwoofer is more appropriate to sound reinforcement applications than to hi-fi. Once again the entire acoustical output is by way of the outer port, which must have the largest practicable diameter. The inner port also needs to be designed with the issue of port noise in mind, but it is less critical because its noise output will be attenuated by the lowpass action of the front chamber.
