MI-1281, 1/2-inch back electrets-type microphone that is free sound field type,realizes high sensitivity, low noise and does not require bias power has been newly added.  Also, there are MI-1271 which has improved the environmental stability against temperature and humidity, MI-1235 which emphasizes on a wide frequency range and MI-1433 which realizes a similar environmental resistance at a low price. MI series microphone is used in combination with the preamplifier and the microphone. Since microphone and preamplifier are not built-in type, installation costs can be reduced in the event of a fault.

MI-1281

MI-1281

MI-1281 is precision microphone that achieves -20 dB re.1V/Pa of sensitivity, 8 dB of self-noise level (A-weighting, when using MI-3170) although it is 1/2-inch back electrets type. It has a low noise floor that enables measurement of very low noise. In other words, it is efficient for measuring sound power level of noise-reduction home appliances and in semi-anechoic room, and for probing tiny but unpleasant sound source of electric vehicles.

MI-1271

MI-1271 is 1/2-inch back electrets type precision microphone which conforms to IEC 61094-4 Type WS2F(Measurement microphones- Part 4: Specifications for working standard microphones). By adapting laser welding fixation of titanium vibrating membrane, it realizes long-term stability. In addition, wide temperature/humidity range (-30 ℃ to +80℃/ 0 to
90% RH) and wide frequency range (1 Hz to 20 kHz) enable to meet wide variety of applications, such as measurement of environmental noise in high-temperature and humidity environment, measurement of sound with very low frequency (up to 20 Hz), and sound measurement during cold start tests of automobiles.

MI-1235

MI-1235 is best to be used as measurement and analysis for environmental noise, architectural acoustics, and radiated sound from electrical/mechanical instruments. And it has a wide frequency range of 10 Hz to 20 kHz.
It is precision microphone used with the MI-3111 microphone preamplifier.

 

MI-1433

MI-1433 is excellent for environmental noise measurement with frequency range of 20 Hz to 8 kHz. It is general microphone with low cost used with the MI-3111 microphone preamplifier.

 

 

 

 

MI-1271/3170 Product video (YouTube)

 

System Configuration

Each product illustration in the below configuration is linked to its own page.



Specifications

Model name

MI-1281 MI-1271 MI-1235 MI-1433
Response type Free sound field
Positive voltage 0 V
Sensitivity (1 kHz) -20 dB±1.5 dB re. 1 V/Pa 100 mV/Pa (1 kHz) -26 dB±1.5 dB re. 1 V/Pa
50 mV/Pa (1 kHz)
-29 dB ±3 dB re. 1 V/Pa
36 mV/Pa (1 kHz)
Capacitance (1 kHz)

14 pF

(Representative value)

12 pF

(Representative value)

13 pF
(Representative value)
Frequency range
(1 kHz at standard)

10 Hz to 20 kHz

(+1.5 dB,-5 dB)

10 Hz to 10 kHz

(+1.5 dB, -2 dB)

1 Hz to 20 kHz
(±2 dB)
10 Hz to 20 kHz
(+1.5 dB,-5 dB)
10 Hz to 10 kHz
(+1.5 dB,-2 dB)
20 Hz to 8 kHz
(±2 dB)
Effective load volume 364 mm3 359 mm3 260 mm3 239 mm3
Maximum sound pressure level (Total harmonic distortion 3 %)

128 dB

(when using MI-3170)

135 dB

(when using MI-3170)

135 dB(when using MI-3111)
141 dB(when using MI-3170)

Self-noise level

(A-weighting)

8.0 dB

(representative value) 
(when using MI-3170)

14.0 dB

(representative value) 
(when using MI-3170)

19.0 dB (representative value)
(when using MI-3111)
Operating temperature range -10 to +50 ℃ -30 to +80 ℃ -10 to +50 ℃
Operating relative humidity range 0 to 90 %
(with no condensation)

0 to 90 %

(with no condensation)

30 to 90 %
(with no condensation)
Storage temperature range -20 to +60 ℃ -40 to +70 ℃ -20 to +60 ℃
Storage relative humidity range 0 to 90 %
(with no condensation)
10 to 90 %
(with no condensation)
Weight Approx. 6 g
Outer dimension φ13.2 mm × 16.9 mm φ13.2 mm × 16.9 mm φ13.2 mm × 13.7 mm φ13.2 mm × 13.5 mm

Preamplifier

MI-3170

MI-3170 1/2

MI-3170 is a preamplifier for 1/2-inch back-electret type condenser microphone, it can be used in combination with a microphone such as MI-1281/MI-1271. Adopting the CCLD method and BNC connector, various types of CCLD accepted amplifier, analyzer and data recorder can be connected directly. When combined with MI-1281 high sensitivity microphone, it enables to measure minute sounds since it achieves high sensitivity and low noise characteristics with -20 dB re.1V / Pa of sensitivity, 8 dB of self-noise level (A-weighting). It covers the measurement range of ultra low frequency of 1Hz and can be used in wide operating temperature range (-30 to +80℃) when combined with MI-1271 high-performance microphone.

 

MI-3111

MI-3111 1/2

MI-3111 is a preamplifier for 1/2-inch back-electret type condenser microphone. It is CCLD and BNC connector type.
It is a general preamplifier used with the MI-1235/MI-1433 microphone.

Specification

Model name MI-3170 MI-3111
Applicable microphone MI-1281/MI-1271/1235/1433
(Discontinued)MI-1233/1234/1431/1432
MI-1235/1433
(Discontinued)MI-1233/1234/1431/1432
Insertion loss 0.15 dB (at 1 kHz)(representative value) 1.0 dB(representative value)
Frequency range

10 Hz to 40 kHz

(+0.1 dB,-0.2 dB,1 kHz as reference)
1 Hz to 40 kHz

(+0.1 dB,-1.5 dB,10 Hz as reference)

10 Hz to 20 kHz
(±1.0 dB,1 kHz as reference)
20 Hz to 20 kHz
(±0.6 dB,1 kHz as reference)
Input impedance 40 GΩ 5 GΩ±15%

Self-noise

(effective voltage)

A-weighting: 3.3 µV or less
(Sound pressure conversion 8 dB)
MI-1271 sensitivity: -26 dB re. 1 V/Pa
A-weighting: 5.0 µV or less
(Sound pressure conversion 17 dB)
MI-1271 sensitivity -26 dB re. 1 V/Pa
Total harmonic distortion
0.0316 % or less
(Input frequency 1 kHz, Input effective voltage 1 V)
0.1 %(-60 dB) or less
(Input frequency 20 kHz, Input effective voltage 1 V)
1 % or less
(Input frequency 1 kHz, Input effective voltage 3.15 V)
DC bias voltage 12 V ± 2 V 8 V ± 1 V
Maximum output voltage ±8 V (Peak) (driving power 24 VDC, 4mA)
Sound pressure conversion135 dB
(Sensitivity 50 mV/Pa when using microphone)
±5.6 V (peak) (driving power 24 VDC, 4mA)
Sound pressure conversion 135 dB
(Sensitivity 35 mV/Pa when using microphone)
Operating temperature range -30 to +80 ℃ -10 to +50 ℃
Operating relative humidity range 0 to 90 %(not including microphone) 30 to 90 %(not including microphone)
Storage temperature range -40 to +70 ℃ -20 to +60 ℃
Storage relative 0 to 90 %(not including microphone) 10 to 90 %(not including microphone)
Power supply CCLD
2 to 4.5 mA,DC 18 to 26 V
CCLD
0.5 to 5 mA,DC 15to25 V
Applicable connector C02(BNC)
Weight Approx. 35 g (not including microphone) Approx.25 g(not including microphone)
Outer dimension φ12.7 mm × 80.5 mm φ12.7 mm × 63.5 mm
Accessory

Protection cap for input connector×1
Microphone holder (MI-0301)×1
Instruction manual x1

Protection cap for input connector×1
Microphone holder (MI-0301)×1
Instruction manual x1
Extension cable MX-1000 series (recommended), MX-2000 series MX-2000 series (recommended)

 

Connection cable (both terminals are BNC connector)

Model name Outer dimension Length Operating temperature range
MX-1001 Signal cable for low/ high temperature
MX-1000
1.5 m -30 to +80 ℃
MX-1005 5 m
MX-1020 20 m
MX-2001 MX-2000 1.5 m -10 to +60 ℃
MX-2005 5 m
MX-2020 20 m


Revised:2020/03/31



 

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