General Rules For Microphone Use - Shure BG4.1 Guia Del Usuario

MODEL BG4.1
UNIDIRECTIONAL CONDENSER MICROPHONE
The BG4.1 microphone utilizes an advanced condenser
transducer design for use in professional instrument sound re-
inforcement and project studio recording. Its electret cartridge
has a wide frequency response for natural sound reproduction,
and its high sensitivity and low noise make it an ideal choice
for producing quality demo tapes. The BG4.1 also maintains
a cardioid polar pattern throughout its frequency range which
ensures high gain-before-feedback and maximum isolation
from undesired sound sources. Operating voltage is supplied
by phantom power from a mixer, or an internal AA battery for
10,000 hours of continuous use. Typical applications for the
BG4.1 include acoustic guitar, drums, stringed instruments,
and vocals (when mounted on a stand).

GENERAL RULES FOR MICROPHONE USE

1. For optimal signal-to-noise ratio, place the microphone as
close as possible to the desired sound source.
2. For the best gain-before-feedback and isolation from unde-
sired background noise, aim the microphone toward the
sound source and away from undesired sound sources
(Figure 1). The BG4.1 features a cardioid polar pattern
which is most sensitive to sound directly in front of the mi-
crophone, and least sensitive to sound directly at 180_ .
3. For the purest reproduction of sound, use only one micro-
phone per sound source and use the fewest number of mi-
crophones necessary for the application.
4. For maximum isolation, keep the distance between micro-
phones at least three times the distance from each source
to its microphone.
5. Placing the microphone close to the sound source improves
bass response (Figure 2). This phenomenon is known as
proximity effect and can be used to achieve a fuller sound,
and to change the bass output of an instrument without us-
ing tone controls. Proximity effect is also especially good
for vocals during soft passages where emphasis is needed.
6. Placing the microphone too close to acoustically reflective
(smooth, hard) surfaces will result in a poor frequency re-
sponse and will increase the chances for feedback. T o mini-
mize this effect, place microphones as far as possible from
acoustically reflective surfaces.
7. Add an external windscreen when using the microphone
outdoors to reduce wind noise.
8. It is important to keep foreign particles out of the grille and
the windscreen because they may alter the frequency
response of the microphone. Also, avoid exposing con-
denser microphones to heat and high humidity.
SPECIFICATIONS
Type
Condenser (electret bias)
Frequency Response
40 to 18,000 Hz (Figure 2)
Polar Pattern
Cardioid (unidirectional), symmetrical about axis
(Figure 3)
Output Impedance
600 Ω
Recommended Input Load Impedance
800 Ω minimum
Output Level (at 1,000 Hz)
Open Circuit Voltage
1 Pascal=94 dB SPL
Maximum SPL
2,000 Ω load
800 Ω load
. . . . . . . . . . .
. . . . . . . 131 dB (phantom), 127 dB (battery)
. . . . . . . . 129 dB (phantom), 126 dB (battery)
–48.0 dBV/Pa (4.0 mV)
2