This Chart contains models currently, In Production, for ordering and older Models for cross-reference purposes. Chaparral Physics is very willing to make special versions to meet your requirements.

Frequency Range
of Sensor		 Model Type
Year Introduced		 Status Key Differences Operating Voltage Availability
0.1 Hz to > 100 Hz Globe 100, ~1964? Replaced w/ Model 25 Original Sensor 24-28 Not in Production
0.1 Hz to > 100 Hz 2, ~1980's Replaced w/ Model 25 Original Sensor 24-28 Not in Production
0.1 Hz to > 100 Hz 2.1, 2004 Replaced w/ Model 25 Thicker base plate 24-28 Not in Production
0.1 Hz to > 100 Hz 2.2A, 2005 Replacements only 9-18 volts 9-18 Special Order, Superseded by Model 20-21
0.1 Hz to > 100 Hz 2.2B, 2005 Replacements only Low power 24-28 Special Order, Superseded by Model 20-21
0.1 Hz to > 100 Hz 2.2C, 2005 Replacements only ultra-Low Power
(non-linear output)		 12-15 Not in Production
0.1 Hz to > 100 Hz 2.5, 2005 Replacement only Built-in manifold 9-18 Special Order, Superseded by Model 24-25
0.1 Hz to > 300 Hz 7, 2000 Test Model Small & light 24-28 Not in Production
0.1 Hz - 200 Hz 20, 2008 Low Cost Model Sealed Electronics
Diff. Output
Single Gain
No Self-test		 9-18v In Production
0.1 Hz - 200 Hz 24, 2008 Low Cost Model Sealed Electronics
Diff. Output
Built-in Manifold
Single Gain
No Self-test		 9-18v In Production
0.1 Hz - 200 Hz 21, 2008 Std. Model Sealed Electronics
Diff. Output		 9-18v In Production
0.1 Hz - 200 Hz 25, 2006 Std. Model Sealed Electronics
Diff. Output
Built-in Manifold		 9-18v In Production
0.1 Hz - 200 Hz 2x V, E, 2008 Custom Models Special Versions 9-18v As requested
0.02 Hz to > 50 Hz 4, 1998? Older CTBT
Prototype Model		 Original/broadband 24-28 Not in Production
0.02 Hz to > 50 Hz 5.0, 1999 Old CTBT Model
Replacement only		 Improved Broadband #1 9-18 Not in Production
0.02 Hz to > 50 Hz 5.1, 2000 Replacements only Improved Broadband #2 9-18 Not in Production
0.02 Hz to > 50 Hz 5.2, 2001 Replacements only Improved Broadband #3 9-18 Not in Production
0.01 Hz - 50 Hz 50, 2005 Broadband Model Sealed Electronics,
Diff. output,
Low Noise		 9-18v In Production

Since the acquisition of Chaparral Physics Consultants of NM, and converting it into the Chaparral Physics division of the Geophysical Institute, University of Alaska, in early 2004, we have been in a continuous process of updating, improvements, and bringing the Chaparral Physics product line sensors into the 21st century. With our new models in production, the Model 25 and Model 50, we believe we have finally achieved significant improvements in infrasound sensor technology.

The Model 50 is presently the king of all infrasound sensors; it has broadband response and very low sensor self-noise,. While it is an observatory grade sensor it can be used for quick field deployments, as its IP 67 rating and all stainless steel and Acetal exterior are weather resistant. It can be used to replace the MB2000 and MB2005, or any of the old NBS sensors such as the N4, as it exceeds the performance of all of those sensors. It also exceeds the performance of all of Chaparral Physics own broadband models, such as the 5.x series. Even if you only are interested in the 0.1 to 20 Hz near infrasound band, you may want to consider the Model 50 as its noise specifications are much better than our own more economical 20 series.

The Model 25 is the current successor to the original Globe and Chaparral Physics Consultant’s lines of sensors. The Model 25 exceeds the performance of all our own past Model 2.x sensors also. The Model 2.5 and Model 25 both have the built-in 4 port manifold complete with Garden hose thread connectors, with an option for 1 to 12 inlet ports, thus potentially saving you the cost of building manifolds for use with wind noise reducing systems. While the Model 25 is very similar to the model 2.5 it has the built-in self-check features of the Model 50 and well as the differential output signal.

Acoustic Spectrum of Gravity Waves thru Infrasound to Ultrasound
acoustic spectrum diagram
Figure 1. Relationship of Chaparral Physics sensor models to the Infrasound Bands.

Sensor noise plots and response plots
sensor noise diagram

Figure 2. Typical Chaparral Physics sensor self noise plots for both the Model 50 (Red) and Model 25 (Violet). The Red dotted line is the Global Low Wind median noise curve of a collection of globally diverse infrasound stations. The Blue dotted line is the Global Low Noise Curve derived from the lowest noise measured at any of the global stations at each frequency. In cases where low noise is important one should consider using the Model 50 even if the broad bandwidth of the Model 50 is not need, since the Model 50 has a lower sensor self noise, than the Model 25.

The global noise data is extracted from: Bowman, J.R., G.E. Baker, and M. Bahavar, Ambient Infrasound Noise, Geophys. Res. Lett., 32, L09803, doi: 10.1029/2005GL022486, 2005, and private communications.