Polar variations with frequency
Whether particular frequency components add or subtract in the far field will depend on the loudspeaker system spacing, the angular offset of the listener with respect to the centre line, and the wavelength.
The following polar responses show what happens when subwoofers are placed 8.6m apart and are driven in unison at various frequencies:
100Hz
The polar plot shows the far field polar response of the two subwoofers when driven in phase with the same 100Hz signal. Subwoofer interaction causes irregular coverage either side of the centre line.
Response nulls (cancellations) occur at the sides because the spacing is an odd number of
80Hz
The above shows the same system at 80Hz.
At this frequency the central position remains well covered but the polar pattern has changed dramatically around the sides. There are now strong lobes at the sides because the spacing is now an even number of half- wavelengths at this particular frequency.
All material © 2007. Martin Audio Ltd. Subject to change without notice.
