4.5 Microphone
4.5 Microphone
Only the original microphone capsule MK255 by MICROTECH GEFELL is approved for measurements with
Tango_Plus. The directional characteristics of the microphone correspond to the limits specified in IEC
61672-1:2003. The effect of the windscreen on the directional characteristics of the microphone is negligible.
As a result all corresponding correction values are specified with pm0.1 dB. The acoustic center point and
microphone reference point are located at the middle of the microphone membrane.
Property Value
Model Transducer type Capacitive pressure transducer
Polarization backelectret
Frequency range free-field 3.5 Hz . . . 20 kHz (±2 dB)
Sensitivity ca. 50 mV/Pa
Max. SPL for 3 % , distortion at 1 kHz 146 dB
Self-generated noise with preamplifier 15 dBA
Capacitance 17 pF
Operating temperature range -50 . . . +100
◦
C
Ambient temperature coefficient leq0.01 dB/
◦
C
Ambient pressure coefficient -0.01 dB/kPa
Diameter 1/2”
with protection lid 13,2 ± 0,02 mm
without protection lid 12,7 ± 0,02 mm
Length 16,4 mm
Weight 7,5 g
Thread for preamplifier 11,7 mm 60 UNS
Thread for protection 12,7 mm 60 UNS
Table 4.6: Technical data MK255
4.5.1 Random incidence and free-field correction
f Freifeldkorr. Diffusfeldkorr.
in Hz in dB in dB
25 0 0
31.5 0 0
40 0 0
50 0 0
63 0 0
80 0 0
100 0 0
125 0 0
160 0 0
200 0 0
250 0 0
315 0 0
400 0 0
500 0 0
630 0 0
f Freifeldkorr. Diffusfeldkorr.
in Hz in dB in dB
0.8 k 0 0
1 k 0 0
1.25 k -0.03 0
1.6 k 0.03 0
2 k 0.21 -0.1
2.5 k 0.36 -0.1
3.2 k 0.56 0
4 k 0.88 0.1
5 k 1.36 0.2
6.3 k 2.01 0.4
8 k 2.99 0.7
10 k 4.25 0.9
12.5 k 6.14 1.8
16 k 8.77 3.4
20 k 9.9 3.2
Table 4.7: Free-field and random incidence corrections (manufacturer’s specification: measurement uncertainty at 95% certainty ±0.6 dB)
SINUS Messtechnik GmbH 25 of 30 Manual Tango_Plus
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