Mic Archive
Shure Beta 91A
Photo: Shure, from its spec sheet (Recording Hacks copy), p. 1.

Shure

Shure Beta 91A

Boundary condenser, half-cardioid (kick drum, piano)

Type
Condenser (electret)
Pattern
Half-cardioid
Sensitivity
−48.5 dBV/Pa
Self-noise
29.5 dB(A)
Max SPL
155 dB SPL
Impedance
146 Ω
Rated range
20 – 20k Hz

Frequency response

Angle
Distance

Frequency response: from the spec sheet (Recording Hacks copy), p. 1. On a boundary (the mic lies on a surface). Measured at 61 cm (2 ft), as printed on the graph. Anechoic or not, smoothing and typical-vs-individual are not stated.

Dashed: outside the rated range, or simulated (other angles and distances). Hover or tap the graphs for values.

Polar pattern

Polar pattern: from the spec sheet (Recording Hacks copy), p. 1. Full circle as printed, 0° at the bottom. Measuring conditions not stated. The sheet calls the pattern half-cardioid: cardioid in the hemisphere above the mounting surface.

Compare with other mics

All specs

From the spec sheet (Recording Hacks copy)
Sensitivity−48.5 dBV/Pa (3.8 mV/Pa), open circuit voltage, 1 kHz, typicalp. 2
Self-noise29.5 dB(A), equivalent SPL, A-weighted, typical
Max SPL155 dB SPL, 1 kHz, 1% THD, 2500 ohm load; also 151 dB SPL, 1 kHz, 1% THD, 1000 ohm load. THD of the preamplifier when its input equals the cartridge output at that SPL (footnote 2).
Signal-to-noise ratio64.5 dB, re 94 dB SPL, A-weighted
Dynamic range125.5 dB, 1 kHz, 2500 ohm load; also 121.5 dB, 1 kHz, 1000 ohm load
Output impedance146 ohm, 1 kHz
Rated load impedance1000 ohm, minimum recommended
Rated frequency range20 Hz to 20 kHz. Tolerance not stated. The printed graph starts at 50 Hz.
Poweringphantom, 11–52 V DC (IEC-61938). Specs measured at 48 V; works down to 11 V with less headroom and sensitivity.
Current draw5.4 mA
Switchescontour: flat, low-mid scoop. Page 2: "7 dB of attenuation centered at 400 kHz". The graph shows the dip at about 400 Hz, so "kHz" is a typo.p. 1
ConnectorXLR-3 male. "Three-pin professional audio (XLR), male, balanced"; built into the mic body.p. 2
Weight470 g
Dimensions139.1 × 95.11 × 20.3 mm. Length × width × height, from the dimension drawing.
Supplied accessoriesZippered carrying bag (95A2314)
Clipping Level (20 Hz to 20 kHz, 1% THD)2500 Ω load: 12.5 dBV; 1000 Ω load: 7.5 dBV
Common Mode Rejection (20 Hz to 200 kHz)≥55 dB
Frequency Contour Switch7 dB of attenuation centered at 400 kHz
PolarityPositive pressure on diaphragm produces positive voltage on pin 2 with respect to pin 3
Optional Accessories7.6 m (25 ft.) Cable, C25E
Replacement PartsCardioid Cartridge, RPM98A/C
CertificationCE; European EMC Directive 2004/108/EC; EN55103-1:1996 and EN55103-2:1996 (E1, E2)
From the user guide (Recording Hacks copy)
Placement (kick drum)Inside drum, on a pillow or other cushioning surface, 25 to 152 mm (1 to 6 in.) from beater headp. 3
Placement (piano)Underside of lid over lower treble strings; or vertically on the inside of the frame near the apex of the curved wall

Documents

Copies kept by Mic Archive, because manufacturers move and drop their documents. Each is © Shure, unchanged, with its original address.

Product page on shure.comRecording Hacks

Recommended for

Instruments whose sources name this mic, or an earlier version or variant of it.

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