General Description, Features, Contour Switch

General Description

The Shure Beta 91A is designed for use with kick drums, piano and other traditional low frequency ap- plications. An updated microphone capsule is tailored for bass-heavy environments to produce a powerful low frequency response, and a new design integrates the preamplifier and XLR connection for easy setup and minimal stage clutter. The Beta 91A combines superior attack and punch for studio-quality sound, even at ex- tremely high sound pressure levels (SPLs).

Features

•Premier live performance microphone with Shure quality, ruggedness, and reliability

•Uniform half-cardioid polar pattern (in the hemisphere above mounting surface) for maximum gain before feedback and rejection of off-axis sound

•Tailored frequency response for kick drums and bass-heavy instruments

•Wide dynamic range for use in high SPL environments

•Two-position contour switch enhances attack and clarity

•Integrated preamp and XLR connector reduce stage clutter and provide a quick, secure setup

•Low profile design requires no external mounting hardware

•Steel grille and die-cast metal construction resist wear and abuse

Performance Characteristics

•Exceptional low-frequency reproduction

•Extremely high SPL handling

•High output level

•No crossover distortion

Applications and Placement
Half-cardioid Polar Pattern
Boundary microphones pick up sound in a cardioid polar pattern in the	60
hemisphere above the mounting surface. Keep sound sources within the
60 degree range above this surface.

General Rules for Use

•Aim the microphone toward the desired sound source; angle unwanted sounds toward its null point.

•Use the fewest amount of microphones as practical to increase the Potential Acoustic Gain and prevent feedback.

•Follow the 3 to 1 Rule by spacing each microphone by at least three times the distance to its source to reduce Phase Cancellation.

•Place microphones as far as possible from reflective surfaces to reduce Comb Filtering.

•When using directional microphones, work closely to the microphone for extra bass response to take advantage of Proximity Effect.

•Avoid excessive handling to minimize pickup of mechanical noise and vibration.

•Do not cover any part of the microphone grille, as this will adversely affect microphone performance.

The following table lists the most common applications and placement techniques. Keep in mind that microphone technique is largely a matter of personal taste; there is no one “correct” microphone position.

APPLICATION	SUGGESTED MICROPHONE PLACEMENT	TONE QUALITY
Kick Drum	Inside drum, on a pillow or other cushioning surface, 25	Full, natural sound.
	to 152 mm (1 to 6 in.) from beater head.
	Contour switch activated; 25 to 152 mm (1 to 6 in.) from	Sharp attack; maximum bass
	beater head.	“punch.”
Piano	Mount microphone on underside of lid over lower treble	Bright, well-balanced, strong
	strings. Experiment with lid height and placement to ham-	attack; excellent isolation.
	mers for desired sound.
	Mount microphone vertically on the inside of the piano	Full, natural; excellent isola-
	frame, near the apex of the piano’s curved wall.	tion and minimal hammer and
		damper noise.

Note: Location and room acoustics strongly affect the sound quality of microphones. To achieve the best overall sound for a particular application, it may be necessary to experiment with microphone placement and

room treatments.

Mounting the Microphone

For long-term installation, mount the Beta 91A to a surface using the mounting holes on the bottom of microphone.

Contour Switch

A two-position switch on the bottom of the microphone lets you selectively filter the low-mid frequency response with- out additional tools. Use this filter to enhance the attack and clarity of bass-heavy instruments.

	Flat response: Provides the most natural sound in most applications.
	EQ
EQ	Low-Mid Scoop: This setting tailors the microphone’s frequency
	response to provide a strong ‘punch’ in the low frequencies, and
	plenty of attack in the higher frequencies.