F100/F50 Square Impedance Tube

F100/F50 square impedance tube is designed base on transfer-function method, according to GB/T 18696.2, GB/J 88, ISO 10534-2, ASTM E1050-12, and ASTM E2611-17 standards, including absorption tube kit and transmission loss tube kit.

The absorption tube kit of F100/F50 is based on two-microphone transfer-function method. The normal incidence sound absorption coefficients and specific acoustic impedance ratios of materials in the full measurement frequency range can be obtained only by one test. Compared with the tube designed based on the standing wave ratio method, it significantly improves the test efficiency of material acoustic properties. And the transmission loss tube kit is based on four-microphone transfer-function method. The transmission loss of materials to be measured can be obtained by measuring the sound pressure level at four fixed positions in tube with two different terminations and calculating a complex transfer function.

The inner side length of F100 impedance tube is 102 mm, test frequency range is 45 Hz ~ 1.6kHz. The inner side length of F50 impedance tube is 50mm, test frequency range is 800 Hz ~ 3.55 kHz. Made of hard aluminum alloy, with compact design, light weight and easy to assemble, which is convenient for measuring acoustic properties of materials at various places.


⚫ Acoustical properties of material measurements based on the transfer-function method according to not only absorption coefficient standard of GB/T 18696.2, GB/J 88, ISO 10534-2 and ASTM E1050-12, but also transmission loss standard of ASTM E2611–17

⚫ Separable sample holder tube is convenient for placement of materials to be test

⚫ Faster and more accurate compared to the standing wave ratio method

⚫ Frequency range can cover high and low bands, depends on various diameter of tube and the different microphone spacing

⚫ Improved sealing and connecting structures between tubes are convenient for measurement and has much better sealing and sound insulation performance


⚫ Quantitative measurement of acoustic properties of materials

⚫ Measure the acoustic coefficients of materials which required for simulation software

Impedance Tube


Absorption Tube

Transmission Loss Tube





GB/T 18696.2、GB/J 88、ISO 10534-2、ASTM E1050-12

ASTM E2611-17

Frequency Range

45 Hz~1.6 kHz

800 Hz~3.55 kHz

45 Hz~1.6 kHz

800 Hz~3.55 kHz

Side Length

102 mm

50 mm

102 mm

50 mm

Length of Tube1

828 mm

703 mm

1288 mm

1074 mm

Zero Absorption

45 Hz ~ 4 kHz: <5 %

(Calculated in 1/3-octave band)

Note 1: The length is the minimum combination state.


                     Rated Impedance

4 Ω




89.8 dB (2.83 V@1 m)

Rated Power

10 W (continuous)

Peak Power

30 W (short duration: duty cycle 1/3, on time 50 s)

Audio Interface

Banana socket

Measurement Microphone


MPA416 Prepolarization Microphone



Sensitivity (±2 dB)

50 mV/Pa(-26 re 1 V/Pa)

Output Impedance

< 110 Ω

Dynamic Range

29 dBA~127 dB

Self-generated Noise

29 dBA

Power Supply


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F100/F50 Square Impedance Tube