The L30B is a diameter30 mm sphere shaped
Acoustic Pressure Equaliser, designed for use with the Standard
Microphone 4003 and 4006 or the A-B
Stereo Kits 3503 and 3506.
It gives a mild modification of your
microphone's on-axis and
off-axis frequency responses, and a slight change in the direction-to-
reverberation ratio.
This will give your recordings greater presence, nearness and clarity on-axis (especially around 4
kHz).
An on-axis boost, between 2 and 8
kHz, and high-
frequency roll-off off-axis, will sometimes help you capture the subtle audible details of both musical instruments and voices.