DPA Microphones DPA APE Acoustic Pressure Equalizer Ball for 4006

A pressure omni measures flat in a diffuse field but loses on-axis top end as the wavelength approaches the capsule size. The APE sphere is the classical fix: putting a ball in front of the diaphragm raises the on-axis high frequencies back up, so a distant main pair keeps its air without EQ.

The size sets how much lift and from what frequency. The 30 mm ball is the gentlest, the 50 mm the most pronounced; choose by how far the microphone is from the source. All three fit the 4006 microphone and the matched 4006 pairs and surround kits.