Beaming:
- Beaming is kin to the acoustic low-pass (discussed in the following post).
- Beaming is a function of the effective driver size: the dispersion narrows as the wavelength (frequency) becomes smaller than the size of the drive unit.
Note: Effective driver size is taken from 1/2 surround to 1/2 surround. - All drivers beam! Though, some drivers are built to extend further on a given axis than others, but often at a cost (sensitivity, cone breakup, etc).
- Frequency response measurements illustrate beaming easily; look for the on and off-axis responses to diverge. This is your beaming point.
- The formula to approximate the beaming point is: 0.5*(Speed of Sound)/(Driver Size)
- Below is a table illustrating approximate beaming points for a round driver with a given cone diameter: