Model 50A

The leading sensor for precision infrasound research.

The Chaparral Physics Model 50A Infrasound Sensor represents the cutting edge of low noise, high resolution, wide-bandwidth infrasound sensing technology. This observatory grade instrument has class leading low noise characteristics, coupled with extremely wide bandwidth, low sensitivity to seismic and thermal noise, and robust environmentally sealed construction. The Model 50A is an excellent choice for anyapplication requiring infrasonic data of the highest quality. It excels at accurately recording very weak acoustic signals with excellent signal to noise ratio, down to thelowest frequencies. If your application requires the highest quality infrasound data, the Chaparral Physics Model 50A provides you with a no-compromise solution.


Nominal Sensitivity
High: 2.0 volts/Pa @ 1 Hz, 18 Pa full scale range
Low: 0.4 volts/Pa @ 1 Hz, 90 Pa full scale range
Individual sensor’s calibrated value is +/-5% from nominal. Calibration value istraceable to the Los Alamos National Laboratory (LANL) calibration chamber.
Output Type: Differential
Maximum 36 volts peak-to-peak (signal+ to signal-)
Frequency Response Flat to within +0, -3 dB from 0.01 Hz to 50 Hz 
Flat to within +0, - 0.5 dB from 0.06 Hz to 10 Hz
Self Noise Less then -76dB Pa²/Hz, rel to 1 Pa
Less than 0.8 mPa RMS, 0.02 to 50 Hz
Less than 0.2 mPa RMS, 0.5 to 2 Hz
Dynamic Range 99dB high gain, 113dB in low gain @ 0.5 Hz to 2 Hz
Output Impedance 150Ω non-reactive, (recommend load >10kΩ)(Recommended less than 10,000pf loading)
Short circuit protected signal+ to signal–, and signal to ground
Power Requirements
DC Source 12 volts (9-18 volts) DC, reverse voltage protected.
Current Drain Less than 40 ma @ 12 v
Sensor will function in any position or attitude. Sealed to IP-64 with acoustic inlet sealed and mating electrical connector installed.
Operating Temperature -40℃ to + 65℃
Humidity 95% (non-condensing)
Dimensions 16.5” (42 cm) maximum height, 9.9” (25 cm) maximum diameter
Weight 17.6 lbs (8 Kg), for 4-port version
Std. Acoustic Inlets 4 inlet ports (maximum 12), male, Garden-Hose-Thread,and a calibration port. Total fore-volume of a 4 port Model50A with capped GHT inlets is ~55 cubic cm.

Model 50A Specifications (PDF)

Model 50A Manual(PDF)