LOUD SPEAKER BAFFLES

Hawke's Bay Tribune, Volume XXI, Issue 243, 26 September 1931, Page 14

LOUD SPEAKER BAFFLES

RADIATION OF BASS NOTES. “Does the size of a baffle for a loudspeaker have any bearing on the output from the speaker? If the speaker is arranged to give a certain output, must 1 use a larger baffle if 1 increase the volume, for the sound waves at any given point around the speaker have surely increased in amplitude,” asks a correspondent in “Popular Wireless.’’ There is no question of amplitude here. It is merely a question of frequency characteristic. Thus, a baffle is useful in producing a stronger (directional) radiation of the bass notes. Imagine the diaphragm of the speaker to move very slowly and imagine there is no baffle. The air, instead of being compressed in front of the forward-moving diaphragm, escapes sideways and behind the diaphragm. A baffle prevents the escape, or at any rate, makes the path of the escape larger. As a matter of fact, the required baffle size is a fraction of the wave-length, but the wave-length of sound waves at 50 cycles is nearly 22ft. and a half-wave baffle would be lift, across. Obviously, physical considerations limit theoretical desires, and “make a baffle as big as may be” is a good motto provided the diaphragm is not already putting too much “bass” m the reproduction.