Boundary microphone for bass drum recording

• Shure has been manufacturing boundary microphones since 1984 in several successive models (SM91, SM91A, Beta 91, Beta 91A)
• the Beta 91A is the first to have the amplifier section integrated in the housing
• electret capsule with half-cardioid polar pattern
• withstands very high sound pressure levels
• adjustable filter for lower mids to optimize the bass drum sound
• powerful low frequeny response
• punchy attack sound
• easy to place
• manufacturing period: since 2007 (SM91: 1984-1993, SM91A: 1993-1999, Beta 91: 1999-2007)

Favourite applications: Bass drum recording, where the Beta 91A is placed inside the drum. Often in combination with another microphone in front of the resonant head of the bass drum (e.g. AKG D12, AKG D112)