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GeoSpectrum M4 Hydrophone Specification
version 1.1, February 2000

M4( -204.6 dBV, 6 nF)



A compact, high frequency hydrophone with an operating depth greater than 2500 m. Designed for continuous immersion in isoparaffinic fluids and water. Low cost in high volumes.

The M4 hydrophone is a low cost hydrophone when produced in high volumes. It is designed for immersion in hydrocarbons, but will maintain its high lead resistance after months of immersion in sea water.

It is available in a package that couples acoustic pressure to the hydrophone, but decouples it from mechanical forces, making it ideal for use in solid-core or gel-filled streamers.

Electrical Characteristics  
Voltage Sensitivity
-204.6 ± 1.5 dBV re 1 µPa @ 20 °C, 1 Hz

5.9 nF ± 15% nF @ 20 °C, 1 kHz

Charge sensitivity

35 nC/bar ± 20% @ 20 °C, 1 kHz

Mechanical Characteristics   
Size: length, width, thickness

37 mm, 13.5 mm

8 grams
5 cc
Operating and Survival depth
> 2500 m
Electrical leads
28 AWG stranded
Water blocked leads
Storage and operating temperatures
-50 to +70 °C
Variation of Voltage Sensitivity
0.3 dBV decrease from 0 to 2500 m 
Electrical insulation between leads

> 1 GW at 20 °C and 70% humidity

Variation of properties with time
Less than 1% per year
UV and Isopar resistance