Type 4191 is designed for high-precision, free-field
measurements where a wide bandwidth is required.
Being externally polarized, Type 4191 must be used
with a classical preamplifier.
USES
Precision measurements to 40 kHz
Premium class sound level meters
Equipment complying with IEC 61672 class 1
FEATURES
Sensitivity: 12.5mV/Pa
Frequency: 3.15 Hz 40 kHz
Dynamic Range: 20 162 dB
Temperature: 30 to +300°C ( 22 to +572°F)
Polarization: 200V
Use of Free-field Microphones
At higher frequencies reflections and diffractions causes
a pressure increase in front of the diaphragm of a microphone.
If not corrected for, this would result in an increased
output voltage. A free-field optimisation means
that the frequency response of the microphone has been
designed in such a way that the free-field response at
0 degrees incidence is flat. This microphone is optimised
for use with the protection grid in place.
Free-field microphones are commonly used for sound
measurement in an anechoic chamber or far away from
reflecting buildings, etc. Another area for free-field microphones
is for general electroacoustic measurements
like loudspeaker and microphone measurements.
With an upper frequency of 40 kHz, Type 4191 is especially
suited all high-precision electroacoustic measurements
as well as general acoustic measurements where a
robust and stable free-field microphone is required. Despite
the 40 kHz upper frequency, this microphone is optimised
to operate with the protection grid in place.
Manufacturing and Stability
A press-fitted, stainless-steel diaphragm ensures superior
long-term stability and mechanical robustness Type
4191 will withstand the 1m drop test of IEC60068 2 32.
All Brüel&Kjær Measuring Microphones are assembled
in a clean room. This ensures that the microphones maintain
their inherent low noise floor and high stability, even
when used in environments with a combination of high
humidity and high temperature.
Polarization Voltage
Type 4191 requires an external polarization voltage and
must therefore be used with a classical preamplifier. Externally
polarized microphones may be used at higher
temperatures without severe changes in sensitivity.
TEDS Microphones
Type 4191 is available in TEDS combinations with the
classical Microphone Preamplifier Type 2669. The TEDS
microphone is considered one unit and has been sealed
in a clean environment. The TEDS is programmed with
the loaded sensitivity of the actual cartridge and the data
is therefore readily available. The default TEDS template
is to IEEE P1451.4 but TEDS to IEEE 1451.4 is available
on request.
Inpidual Calibration Data
Each Type 4191 comes with an inpidual calibration
chart including information about the open-circuit sensitivity,
the free-field frequency response as well as the
electrostatic actuator response.