I am wondering what the minimum size for the two vents of a dipole sub should be, considering the phenomenon of the acoustic impedance.
Rod Elliot (sound.westhost.com) describes the implications for closed box speakers, giving their minimum cone sizes:
<quote>
...small cones (in small boxes) will be incapable of reproducing spectacular bass, regardless of the claimed Xmax of the driver. As an example (and please note that this is a very rough estimate only) the following table shows the expected minimum frequency of various sized drivers in a sealed enclosure having a small baffle, and radiating into ½ space. Vented boxes work differently, but the vent area still limits the low frequency performance. A very large vent (needed for good performance and low noise at extra low frequencies) in an enclosure cannot be effectively driven with a small loudspeaker cone area.
Driver Diameter Minimum Frequency (-3dB)
200mm (8") 40 Hz
250mm (10") 32 Hz
300mm (12") 27 Hz
380mm (15") 21 Hz
450mm (18") 18 Hz
...
</quote>
Anybody?
Rod Elliot (sound.westhost.com) describes the implications for closed box speakers, giving their minimum cone sizes:
<quote>
...small cones (in small boxes) will be incapable of reproducing spectacular bass, regardless of the claimed Xmax of the driver. As an example (and please note that this is a very rough estimate only) the following table shows the expected minimum frequency of various sized drivers in a sealed enclosure having a small baffle, and radiating into ½ space. Vented boxes work differently, but the vent area still limits the low frequency performance. A very large vent (needed for good performance and low noise at extra low frequencies) in an enclosure cannot be effectively driven with a small loudspeaker cone area.
Driver Diameter Minimum Frequency (-3dB)
200mm (8") 40 Hz
250mm (10") 32 Hz
300mm (12") 27 Hz
380mm (15") 21 Hz
450mm (18") 18 Hz
...
</quote>
Anybody?