Hints about selecting the right hydrophone for your application


Ok, it is about 15 years that we deliver hydrophones everywhere. Time to try summarizing the most common question and answers, to help steering your choice to the best model we can deliver.

1. Your budget is ruling the choice?


Hydrophones can cost from something around 250 euros up to several thousands.

If the budget is extremely low:

There are many resources on the web about building you hydrophone starting from a piezo bender. Final cost will be in the range of 25euros. Results will be in an equivalent low range.

If the budget is low:

Basic models, with minijack output that fits MIC INPUT on most electronic devices (but usually NOT tablets and smartphones) are the Aquarian Audio series.
Mainly the H2a model.
Other models from Aquarian Audio are shown here.
The H2a model can be delivered with an XLR output and can be powered via standard phantom power. So it is my preferred solution for arts, music and not-strictly-scientific applications.
If you need a recorder we offer the ZOOM H1 or the ZOOM H2n with accessory pack.

If the budget is intermediate:
Intermediate budgets are more complicate. It is always hard to decide where to put the money.
Our intermediate solutions are:
The Sensor Technology SQ26-08 with 30m of cable
The Aquarian Scientific AS-1 with accessories

If the budget is high or even free:
Higher budgets are nice. We all love them.
We would choose a CRT C57 for most uses. It is wideband, with low self-noise, reliable and easy to use. It comes with an interchangeable cable and a battery box.

2. Your application is ruling the choice?


If you are making music, a movie, a documentary, or just want to listen underwater for your own interest:


and the budget is low:
Basic models, with minijack output that fits MIC INPUT on most electronic devices (but usually NOT tablets and smartphones) are the Aquarian Audio series.
Mainly the H2a model.
Other models from Aquarian Audio are shown here.
The H2a model can be delivered with an XLR output and can be powered via standard phantom power. So it is my preferred solution for arts, music and not-strictly-scientific applications.
If you need a recorder we offer the ZOOM H1 or the ZOOM H2n with accessory pack.

and low budget is not crucial:
The Sensor Technology SQ26-08 with 30m of cable
The Aquarian Scientific AS-1 with accessories
Or best of all the CRT C57. It is wideband, with low self-noise, reliable and easy to use. It comes with an interchangeable cable and a battery box. Can be adapted to fit on underwater canisters and camera cases.
If you have a scientific application dealing with rather low intensity sounds (like Cetaceans whistles):

The Sensor Technology SQ26-08 with 30m of cable and ZOOM recorder. We offer the ZOOM H1 or the ZOOM H2n with accessory pack.
The Aquarian Scientific AS-1 with accessories and a recorder as well (you will need some extra attention to buy the correct preamp for your recorder).
Or best of all the CRT C57. It is wideband, with low self-noise, reliable and easy to use. It comes with an interchangeable cable and a battery box. Can be adapted to fit on underwater canisters and camera cases. It has a MIC level output, single-ended/unbalanced.
If you have a scientific application dealing with rather high intensity sounds (like explosions and pile-driving):

A few models are able to deal with high intensity sounds.
The lowest cost model is the Aquarian Scientific AS-1 with accessories. If you are interested in acoustic analysis you will need a good audio interface to sample the signals. We offer the DAQ200 from SpectraPLUS, which works well with their software and is a calibrated interface.
The AS-1, and most of other models, when used for high intensity signals, do not need extra amplification. Its sensitivity stands at -208dB re 1μPa.

The CRT CR1 is made by Sensor Technology and is also an excellent sensor for high intensity sounds. It has a cylindrical piezo. Stands at -198dB.

The CRT CR2 has a cylindrical sensor also, and it is suitable for louder signals. It is less sensitive. Stands at -214dB.

The CRT CR3 has a spherical sensor, so it is more omnidirectional. Stands at -210dB.

The CRT C57 will be too sensitive. Stands at -165dB.
The CRT C75, which has a spherical sensor, will also be too sensitive. Stands at -186dB.
If you have a scientific application and need a calibrated unit:

The lowest cost model that can be delivered with calibration data is the Aquarian Scientific AS-1 with accessories.
The AS-1can be delivered with external preamp with variable gain. Its sensitivity stands at -208dB re 1μPa.

All CRT models, below, can be delivered with full calibration data or with a spot calibration reading. Spot calibration means that the sensitivity of the unit has been measured at a single fixed frequency and that the full frequency response is assumed to follow the standard table for that model, rescaled at the value measured for that single unit.

The Sensor Technology SQ26-08 with 30m of cable comes with a spot calibration made at a single frequency. Always measured for every single unit.

The CRT CR1 is made by Sensor Technology and is an excellent sensor for high intensity sounds. It has a cylindrical piezo. Stands at -198dB.

The CRT CR2 has a cylindrical sensor also, and it is suitable for louder signals. It is less sensitive. Stands at -214dB.

The CRT CR3 has a spherical sensor, so it is more omnidirectional. Stands at -210dB.

The CRT C57 is a very good, low noise and sensitive sensor. Stands at -165dB.
The CRT C75, which has a spherical sensor, can also be delivered with calibration data. Stands at -186dB.
If you have an application that needs a towable unit:

The most affordable model that can be delivered is the FarONE, which is a towable system assembled using custom made Aquarian Audio H1c/PA4 preamp-line driver.
It is an oil filled pipe, 90cm/1.8m long, with one or two hydrophones and a 80m tow cable. Different assemblies can be made depending on the user needs.
This unit is powered via standard phantom power, so you can directly connect a portable recorder or a computer audio interface (with XLR connectors).
This unit is good for direction finding using a software or your headphones.

More sophisticated towable units are designed together with the customer.