Bruel & Kjaer UK Ltd. - PRODUCT NEWS


Surface Microphone evolves from
Groundbreaking Technology.

The first in a new family of microphones from
Brüel & Kjær using groundbreaking technology
comes the new Surface Microphone Type 4948.

 Designed in close co-operation with a leading aircraft
manufacturer, Type 4948 is an aerodynamic, easy to use,
robust and stable measurement microphone for use on
airplane surfaces during in-flight testing, as well as in
wind-tunnel testing and other similar applications.
It eliminates the many drawbacks of flush mounting experienced
with traditional microphones, as it is not only flat and small
measuring just 2.55mm in height with built-in preamplifier,
but also supports TEDS and is based on new technology.
The compact design makes drilling holes in the test object
a thing of the past, but its measurement performance, stability
and uniformity are equivalent to those of the traditional,
well-known Bruel & Kjaer microphones and amplifiers.

Surface Microphone Type 4948 has a built in DeltaTron®
preamplifier for connection to CCLD inputs.  The microphone
sensitivity is adjusted to allow measurements at high levels
without clipping.  Offering high mounting flexibility with a
diaphragm, which is flush.  The microphone housing and the
metallic parts of the diaphragm-backplate arrangement are
all titanium, ensuring uniquely high resistance to corrosion.
Despite its small dimensions, Type 4948 is corrosion-resistance
and can withstand de-icing detergent and harsh environments
(for example, normal aeroplane cruising altitudes of 30,000 feet,
mach 0.8, turbulence and hailstorms) In addition, the microphone's
pressure equalisation vent is placed next to the diaphragm on
the front of the microphone, a very important prerequisite as
static pressure can vary rapidly with the position in the applications
for which the microphone is designed.

Type 4948 is a pre-polarised pressure microphone and its
features include:
*    Dynamic range: 55 to 160 dB
*    Frequency range: 5Hz to 20kHz
*    Temperature range: -55 to 100oC (-67 to 212oF)
*    Sensitivity: 1.4mV/Pa
*    Built-in DeltaTron®
*    Supports TEDS standard -IEEE P1451.4
*    Flush mounting
*    Optimised for pressure-field measurements

For more information, please contact :-

Bruel & Kjaer UK Ltd.
Bedford House, Rutherford, Close, Stevenage, Herts. SG1 2ND. UK
Tel: +44(0) 1438 739000, Fax: +44(0) 1438 739099

January 2004
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