Truncated ellipsoidal speaker enclosures match spherical performance with more design freedom

Evidence

Second, the volume of the enclosure interacts with the drive unit to set a lower frequency limit for the loudspeaker. Clearly, a sphere cannot have a diameter that is less than the diameter of the drive unit. Truncated ellipsoidal shapes, as shown in Figure 6.64(b), have an additional degree of freedom that, within reason, allows one to set the volume independently of the diameter of the drive unit. … Olson’s results indicate that truncated ellipsoidal shapes, as shown in Figure 6.64, can achieve nearly as good results as a sphere. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2157

Categorization

Category: Factual Claims

• XREF: Connects to the broader argument about how enclosure shape dimensions trade off against acoustic performance — echoes loudspeaker design choices discussed elsewhere in the book.

Related

• Curved small enclosures produce the smoothest acoustic response, ideally spherical (similarity 0.86)
• Loudspeaker enclosure shape and size alter frequency response via diffraction (similarity 0.86)
• Loudspeaker enclosures should curve near drivers and offset them vertically (similarity 0.86)
• Loudspeaker enclosures should curve near drive units to reduce diffraction (similarity 0.85)
• Loudspeaker cabinet volume sets the lower frequency limit (similarity 0.85)
• Loudspeaker enclosures should be curved near drivers and avoid central mounting. (similarity 0.82)
• Cabinet shape and driver placement materially govern diffraction distortion (similarity 0.82)
• Spherical enclosures give the smoothest loudspeaker frequency response (similarity 0.81)
• Loudspeakers need enclosures to stop back-wave cancellation of sound (similarity 0.80)
• Flush-mounting a speaker in a wall reduces the low-frequency rise to 6 dB (similarity 0.79)
• Noncoincident resonances yield smoother speaker response than spherical shapes (similarity 0.79)
• Larger speaker size relative to wavelength enables higher directivity (similarity 0.79)
• Sound diffracts strongly only when wavelengths exceed opening size (similarity 0.78)

Broader Connections

• Noncoincident resonances yield smoother speaker response than spherical shapes #expands (0.80) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2158