Just because a signal - vocal, guitar, drums et al - is loud it still has frequency range that needs to be reproduced accurately. Too often microphone designers roll off their frequency response as a compromise resulting in a muffled sound. Bob Heil's firm stance on designing only large diaphragm dynamic mics - no condensers! - ensures that the signal going in is reproduced faithfully even at high SPL.

When micing a stage with multiple microphones "bleed" is a major issue. Signals from the drum mics, for instance, will find their way into the vocals and the stage sound - as well as the sound out in the house - becomes an unmanageable mush. Bob took a page from his ham radio and antenna design days and created microphones that have a high -40dB of rear rejection.