The APE40 is a Ø40 mm sphere shaped Acoustic Pressure Equalizer, designed for use with the Reference Standard Microphone 4006A or the ST4006A stereo kit. For use with the compact 4006C, the microphone must be either hung or placed in the clip with an XLR connector plugged in.

It offers a more noticeable on-axis boost between 2 and 8 kHz, and stronger off-axis attenuation than the APE30. This gives a marked increase in the directivity of your recordings (at 4 kHz, the front-to-back sensitivity ratio is 8 dB), and decreases the effects of reverberation and off-axis sources.

When using APE40, you can modify the spectral characteristic of a source by simply altering the angle of incidence to give a frequency boost, a flat response or attenuation.

This accessory substitutes the former L40B, suitable for 4003, 4006, 4006-TL and their stereo kits. The L40B cannot be used with the modular series 4006A or 4006C and vice versa.