I've always wondered how the SASS stereo microphone achieves good low-end response from such a small boundary. Is there boost built into the preamp?

Gary Hedden (Happy owner of PZM-6s which have endured unbelievable abuse in Cirque duSoleil recordings.)
GHL Audio
Franklin, TN

Reply: We start with mic capsules that are flat down to 20Hz without any boundaries. Then we add a small boundary (the SASS housing), which boosts the response above 1 kHz due to diffraction. This boost occurs in a free field, but not in a reverberant sound field (like in a concert hall). 

Here's why. Sound waves in a reverberant field approach the mic from all directions. Sounds from behind the mic are picked up with a rolled-off high-frequency response due to the shadowing effect of the SASS housing. In contrast, sounds from the front are picked up with a boosted high end. The responses of the sounds from all directions average out to flat. So the frequency response of the SASS is flat in a reverberant field, without any bass boost in its circuitry.