Features of the Shure BETA91A Boundary Bass Drum Microphone : Uniform half-cardioid polar pattern for maximum gain-before-feedback and rejection of off-axis sound Precision-engineered low-profile design features integrated preamplifier and XLR connector to maximize setup efficiency while minimizing stage clutter Frequency response tailored for kick drum/low frequency applications with a wide dynamic range for use in high SPL environments Two-position contour switch to maximize attack and clarity depending on application: select the flat response setting for natural sound in most applications or the “low-mid scoop” setting for a strong low frequency “punch” with plenty of higher frequency attack Requires no external mounting or accessories for ease of use and storage Furnished with zipper pouch Specifications: Clipping Level (20Hz-20 kHz at 1% THD) 1000 Ohm load: 7.50 dBV, 2500 Ohm load: 12.5 dBV THD of microphone preamplifier when applied input signal is equivalent to cartridge output at specified SPL Self Noise (typical, equivalent SPL, A-weighted) 29.5 dB SPL-A Polarity Positive pressure on diaphragm produces positive voltage on pin 2 with respect to pin 3 Weight Net: 470 g (16.6 oz.) Frequency Contour Switch 7 dB of attenuation centered at 400 kHz Connector Three-pin professional audio (XLR), male, balanced Power Requirements 11-52 Vdc phantom power, 5.6 mA Type Electret Condenser Frequency Response 20 to 20,000 Hz Polar Pattern Half-cardioid (cardioid in hemisphere above mounting surface) Impedance 146 Ohms Sensitivity (at 1 kHz, open circuit voltage) -48.5 dBV/Pa (3.8mV) 1 Pascal=94 dB SPL Maximum SPL (1 kHz at 1% THD) 1000 Ohm load: 151 dB, 2500 Ohm load: 155 dB Signal-to-Noise Ratio (referenced at 94 dB SPL at 1 kHz) 64 dB S/N ratio is difference between 94 dB SPL and equivalent SPL of self noise, A-weighted Dynamic Range (at 1 kHz) 1000 Ohm load: 121.5 dB 2500 Ohm load: 125.5 dB Common Mode Rejection (20 Hz to 20 kHz) > 55 dB
