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Cetacean Research Technology
Underwater and Bioacoustics Instrumentation & Consultation

Cetacean Research hydrophones are manufactured using superior transducers encapsulated in a durable polyurethane. Cetacean Research Technology also carries Sensor Technology hydrophones.

CRT offers both hydrophones and hydrophone systems:

Hydrophone Models:
compare specs

*   SQ26-VR   General purpose hydrophone ideal for kayaking, whale watching and full audio-band signal detection; can also be used as a contact microphone or low cost geophone... more »
* CR1 Excellent multi-purpose non-preamplified hydrophone - great for the detection and recording of both very loud signals and the quieter sounds of cetaceans and other underwater sources.... more »
* CR2 Ideal for the detection and recording of extremely loud signals. Examples of such loud sources include close-range dolphin echolocation, high-power sonar, large pile drivers ... more »
* CR3 new omnidirectional hydrophoneAn omnidirectional hydrophone ... more »
* C55
Cylindrical hydrophones for detection of audible and ultrasonic sounds, with the addition of an integral connector... more »
* C56 new omnidirectional hydrophoneA modular hydrophone, designed to be connected to up to five other C56s... more »
* C75 new modular hydrophoneA preamplified omnidirectional hydrophone ... more »
* C304
Directional receive pattern with very wide frequency response for monitoring ultrasonic signals not detectable by competing brands... more »
* SQ26-01   A reliable, low cost, rugged hydrophone which is integrated into instrumentation... more »

Hydrophone Systems:

*   Noise Measurement   calibrated underwater noise measurement systems - the only PC-based sound pressure level meter in existence to be in compliance with ANSI S1.11 and IEC1260 standards!... more »
* Underwater Recording high-quality underwater sound recording systems - from standard audio to ultrasonic frequencies... more »
* RUDAR™ Remote Underwater Digital Acoustic Recorder for underwater sound recording... more »
* Whale Watching portable listening systems for whale watching - an economical way to get set up quickly... more »

Cetacean Research Hydrophone Specifications Comparison

Model Number

Linear Frequency Range (±3dB) [kHz] 0.0002 to 48
0.002 to 28
0.0004 to 77
Useable Frequency Range (+3/-12dB) [kHz] 0.00005 to 68
0.0004 to 60
0.0001 to 240
Transducer Sensitivity [dB, re 1V/µPa] -198‡
Preamplifier Gain [dB] N/A
SPL Equiv. Self Noise at 1kHz [dB, re 1µPa/√Hz] 38 (< Sea State Zero)
Power Requirement [Vdc] N/A
RMS Overload Acoustic Pressure [dB, re 1µPa] N/A
Maximum Operating Depth [m] 100
Operating Temperature Range [ºC] -25 to 60
-40 to 70
-40 to 90
Capacitance [nF] 10
Dimensions [mm] 73 L x 32 dia
56 L x 14 dia
50 L x 18 dia
Coaxial Cable Length [m] 15

Cable terminated with male BNC connector
(longer cable optional)
all are omnidirectional below 10kHz
at all frequencies
Battery / Connector box power not required

The CR1, CR2, and CR3 hydrophones require a preamplifier with 100MOhms input impedance, such as the Reson VP2000 (PDF) preamplifiers. If a preamplifier with 1MOhms input impedance is used, such as the PC200 (PDF), then the following will occur:

  low frequency -3db point
will be at
   -20db point
will be at
CR1 16Hz instead of 0.2Hz   2Hz instead of 0.02Hz
CR2 200Hz instead of 2Hz   20Hz instead of 0.2Hz
CR3 60Hz instead of .6Hz   6Hz instead of 0.1Hz.

CR1 and CR3 hydrophones are individually spot calibrated at the factory; calibration guaranteed between -5C and 30C.

CR2 hydrophones are not individually calibrated, but calibrated frequency response measurements can be performed for an additional fee.

Model Number

Linear Frequency Range (±3dB) [kHz] 0.015 to 44
0.010 to 85
0.012 to 1000
Useable Frequency Range (+3/-12dB) [kHz] 0.008 to 100
0.003 to 230
0.005 to 2000+
Transducer Sensitivity* [dB, re 1V/µPa] -185
Preamplifier Gain [dB] 20
Effective Sensitivity* [dB, re 1V/µPa] -165
SPL Equiv. Self Noise at 1kHz [dB, re 1µPa/√Hz] 46 (Sea State Zero)
≈ 63
Power Requirement [Vdc] 5 to 32
5 to 32
5 to 32
RMS Overload Acoustic Pressure [dB, re 1µPa] 169 to 186
190 to 207
185 to 202
Maximum Operating Depth ** [m] 460
Operating Temperature Range [ºC] -40 to 60
-40 to 85
-40 to 60
Output Impedance [Ohms] 10
Dimensions [mm] 119 L x (25 to 16) dia. / 130 x 25
101 L x (25 to 18) dia.
83 L x 32 W x (25 to 6)T
Shielded Cable Length [m] mating connector molded to 15, 30, or 50
(other lengths available on a custom order basis)

cable includes Integral Connector (Subconn MCBH3MSS) rated to a depth of 7,000 meters.

all are omnidirectional below 10kHz

very directional at high frequencies (e.g., ~15º solid angle at 200 kHz, 3dB); directionality focused in a plane.

omnidirectional at all frequencies

very directional at high frequencies (e.g., ~15º solid angle at 200 kHz, 3dB); directionality pattern is a dipole.

Battery / Connector box
rated NEMA-4X water resistant, requires
one or two 9V batteries (not included) or
an optional long-life, rechargeable, external power supply. 9V battery life > 20 hrs

standard signal connection is through a watertight female BNC connector with gold center contact

  optional removable in-line high-pass filter
  wire battery box to accept power from external supply

*  Transducer Sensitivity + Preamplifier Gain = Effective Sensitivity.

**  1,000 meter versions of the C55 series, C75, and C304 series hydrophones are available. Append "-1k" to the model number to order a hydrophone with a depth rating >1,000 meters.

C55 series and C304 series Hydrophones are not individually calibrated, but calibrated frequency response measurements can be performed for an additional fee.


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