The MI series are back electrets and sound field type measurement microphones.
The lineup is as follows:
- Measurement Microphone;
- Microphone Preamplifier; and
- TEDS Microphone and
- Low-noise Microphone
MI-1271 is 1/2-inch back electrets type precision microphone.
By adapting laser welding fixation of titanium vibrating membrane, it realizes long-term stability. In addition,
wide temperature/humidity range (-30 °C to +80°C/ 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 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-3120 microphone preamplifier.
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-3120 microphone preamplifier.
The MI-1531 is the 1/4-inch back electrets type microphone and supports a wide frequency range from 10 Hz to 100 kHz. It can measure up to 157 dB in combination with the preamplifier MI-3140.
| Model name | MI-1271 | MI-1235 | MI-1433 | MI-1531 |
|---|---|---|---|---|
| Size | 1/2-inch | 1/4-inch | ||
| Polarization voltage | 0 V | |||
| Sensitivity | -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) |
-48 dB± 3 dB re. 1 V/Pa 4 mV/Pa (250 Hz) |
|
| Frequency range | 1 Hz to 20 kHz | 10 Hz to 20 kHz | 20 Hz to 8 kHz | 10 Hz to 100 kHz (without protection grid) 10 Hz to 20 kHz (with protection grid) |
| Maximum sound pressure | 135 dB (when using the MI-3170) | 135 dB (when using the MI-3120) | 157 dB (when using the MI-3140) | |
| Self-noise level (A-weighting) |
14.0 dB (Typ. value, when using MI-3170) |
19.0 dB (Typ. value, when using MI-3120) |
37 dB (Typ. value, when using MI-3140) |
|
| Operating temperature range | -30 to +80 °C | -10 to +50 °C | -30 to +60 °C (when using the MI-3140) | |
| Operating humidity range | 0 to 90 %RH (with no condensation) | 20 to 90 %RH (with no condensation) | 0 to 90 %RH (with no condensation) | |
| Storage temperature range | -40 to +70 °C | -20 to +60 °C | -30 to +80 °C | |
| Storage humidity range | 0 to 90 %RH (with no condensation) | 10 to 90 %RH (with no condensation) | 0 to 90 %RH (with no condensation) | |
| Outer dimensions | φ13.2 mm × 16.9 mm | φ13.2 mm × 13.7 mm | φ13.2 mm × 13.5 mm | φ7.0 mm × 10.5 mm |
| weight | Approx.6 g | Approx. 1.5 g | ||
| Applicable preamplifier | MI-3170 | MI-3120 | MI-3140 | |
MI-3170 is a preamplifier for 1/2-inch back-electret type condenser microphone, it can be used in combination with MI-1271 microphone. Adopting the CCLD method and BNC connector, various types of CCLD accepted amplifier, analyzer and data recorder can be connected directly. It covers the measurement range of ultra low frequency of 1Hz and can be used in wide operating temperature range (-30 °C to 80 °C).
MI-3120 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.
The MI-3140 is a preamplifier for 1/4-inch back-electret type condenser microphone.
It is CCLD and 10-32 UNF connector type. Ideal for measurement in a limited space.
It is a general preamplifier used in combination with MI-1531 microphone.
| Model name | MI-3170 | MI-3120 | MI-3140 |
|---|---|---|---|
| Size | 1/2-inch | 1/4-inch | |
| Applicable microphone | MI-1271/1235/1433 | MI-1235/1433 | MI-1531 |
| Attenuation (typical) | 0.15 dB (Typ.value at 1 kHz) | 0.3 dB or less (Typ.value at 1 kHz) | 0.35 dB |
| Frequency range | 10 Hz to 40 kHz (+0.1 dB,-0.2 dB, referenced to 1 kHz) 1 Hz to 40 kHz (+0.1 dB,-1.5 dB,referenced to 10 Hz ) |
10 Hz to 20 kHz (within ±0.5 dB, referenced to 1 kHz) | 10 Hz to 100 kHz (±0.5 dB, 1 kHz as reference) (Up to 20 kHz when used in combination with the SR-2210 2ch Sensor Amplifier) |
| Self-noise (effective value voltage, A-weighting) |
3.3 μV or less (10 Hz to 20 kHz) | 5.0 μV or less (10 Hz to 20 kHz) | 2.5 μV or less (20 Hz to 20 kHz) |
| Max. Output voltage | ±8 V (peak) equivalent to 135 dB SPL (when using the MI-1271) |
±5.6 V (peak) equivalent to 135 dB SPL (when using the MI-1235 / 1433) |
±8 V (at DC 24 V) equivalent to 157 dB SPL (when using the MI-1531) |
| Operating temperature range | -30 to +80 °C | -10 to +50 °C | -30 to +60 °C * |
| Operating humidity range | 0 to 90 %RH (with no condensation) | 0 to 90 %RH (with no condensation) | 0 to 90 %RH (with no condensation) |
| Storage temperature range | -40 to +70 °C | -20 to +60 °C | -30 to +80 °C |
| Storage humidity range | 0 to 90 %RH (with no condensation) | 0 to 90 %RH (with no condensation) | 0 to 95 %RH (with no condensation) |
| Power supply | CCLD 2 to 4.5 mA,DC 18 to 26 V | CCLD 2 to 5 mA(rated 4 mA), DC 24 to 32 V(rated 24 V) | CCLD 2 to 20 mA,DC 18 to 25 V |
| Applicable connector | C02(BNC) | 10-32 UNF | |
| Outer dimensions | φ12.7 mm × 80.5 mm | φ12.7 mm × 64.5 mm | φ6.35 mm × 44 mm |
| Weight | Approx. 35 g (not including microphone) | Approx. 25 g (not including microphone) | Approx. 5.5 g (not including microphone) |
| Cable | MX-1000 series (recommended), MX-2000 series (recommended) | MX-2000 series (recommended) | NP-0120 series (recommended), NP-0180 series (recommended) |
| Accessory | Protection cap for input connector× 1 MI-0301 (microphone holder for mounting tripod)× 1 Instruction manual × 1 |
Input protective cap x 1 Preamplifier holder (MI-0301) x 1 Instruction manual x 1 Storage case x 1 Asset Label x 1 |
Protection cap for input connector× 1 SC-0313 conversion adapter (1/2 to 1/4-inch) × 1 Instruction manual × 1 |
*This is the operating temperature range for the main unit only. If the signal cable NP-0120 series is included, the operating temperature range is -25 to 60 °C.
The MI-1271M12 TEDS Microphone can be used by directly connecting to a device equipped with CCLD (Constant Current Line Drive) with BNC cable.
It can be used by connecting directly to equipment equipped with CCLD through a BNC cable. When connected to a TEDS-compatible device, information such as sensitivity will be automatically loaded.
As a result, reliable measurement and time reduction are possible.
| MI-1271M12 | Specification | |
|---|---|---|
| Diameter, response type,polarization voltage | 1/2-inch, free sound field, 0 V | |
| Sensitivity | -26.0 dB ± 1.5 dB re.1 V/Pa (50 mV/Pa) | |
| Frequency range | 1 Hz to 20 kHz (± 2 dB) | |
| Maximum sound pressure level (250 Hz, 3% distortion) |
135 dB | |
| Self-noise level (A-weighting) |
14.0 dB (re.) | |
| Pressure coefficient(250 Hz) | -0.013 dB/kPa | |
| Temperature coefficient(250 Hz) | +0.005 dB/K | |
| Humidity coefficient(250 Hz) | -0.0004 dB/% | |
| Operating temperature range | -30 to +80 °C | |
| Operating humidity range | 0 to 90 %RH(with no condensation) | |
| Storage temperature range | -40 to +70 °C | |
| Storage humidity range | 0 to 90 %RH(with no condensation) | |
| Power requirement | Constant Current Line Drive | |
| Drive current | 2 to 4.5 mA (rated 4 mA) | |
| Drive supply voltage | DC18 to 26 V (rated 24 V) | |
| Output connector | C02 (BNC) | |
| TEDS version** | IEEE 1451.4 : 2004 (Template : Microphone with built-in Preamplifier Ver.1.0) | |
| Outer dimensions | Φ 13.2 X 91.9 mm | |
| Weight | Approx.41 g | |
| Accessory | Calibration chart × 1 Instruction manual × 1 MI-0301 (microphone holder for mounting tripod) × 1 |
|
* Reference environmental condition: 23 °C,50 %RH,101.3 kPa
* Applicable cable length is 30 m or less. Please note that if you extend it more than 30 m, it cannot be conformed to CE marking.
* For TEDS compatibility of measuring device and measurement amplifier to be connected, please contact your nearest distributor or send us an email (overseas@onosokki.co.jp).
In order to create a more comfortable sound environment, there is a need to reduce the operating noise of products such as home appliances and information equipment,
as well as the sound of motors and inverters that transmits into the vehicle interior.
The Low-noise Microphone allows measurements in the 10 dB range (A-weighting), which is difficult to measure with normal microphones.
While conventional low-noise microphone requires a separate amplifier for power supply, this product adapts a CCLD (constant current drive) method and can be used by directly connecting to a CCLD-compatible analyzer.
| MI-1282M10 | Specification | |
|---|---|---|
| Nominal diameter | 1/2 inch | |
| Response type | Free field | |
| Polarization voltage | 0 V | |
| Sensitivity | -6.0 dB ± 2.0 dB re.1V/Pa (500 mV/Pa) | |
| Frequency range | 10 Hz to 20 kHz (±3 dB) 10 Hz to 16 kHz (±2 dB) |
|
| Maximum sound pressure level (1 kHz, 3% Distortion) |
>100 dB (10 Hz to 5 kHz) >80 dB (5 kHz to 20 kHz) |
|
| Self-noise level(A-weighting) | 4.5 dB (Typ.) | |
| Operating temperature range | -10 to +60 °C | |
| Operating humidity range | 0 to 85 %RH (no condensation) | |
| Storage temperature range | -20 to +70 °C | |
| Storage humidity range | 0 to 85 %RH (no condensation) | |
| Power supply | Constant current line drive (CCLD) method | |
| Driving current | 2.8 to 20 mA (rated 4 mA) | |
| Driving voltage | DC24 to 32 V (rated 24 V) | |
| Output connector | C02 type BNC jack (JIS C5412-1995 compliant) | |
| TEDS version | IEEE 1451.4 : 2004 (Template : Microphone with built-in Preamplifier Ver.1.0) | |
| Outer dimension | Φ 13.2 X 91.2 mm | |
| Weight | Approx. 37 g | |
| Accessories | Calibration chart × 1 Instruction manual × 1 Preamplifier holder(MI-0301) x 1 Packing case x 1 |
|
* Reference environmental condition: 23 °C,50 %RH,101.3 kPa
* Cable length should be 20 m or less. Please note that if it is extended to longer than 20 m, it is no longer compliant to the CE marking.
* As for information on TEDS compatibility of the connecting measurement instruments and amplifiers, please contact to the sales offices or distributor nearby.
* Operation is not warrantied when connected to the SR-2210.
Revised: 2026/08/19
