Aquarian Audio Products H2dM User manual

Aquarian Audio
H2dM Hydrophone User’s Guide
The H2dM hydrophone is designed to offer great sensitivity and low self noise in the human
auditory range while being rugged, compact and affordable. Its small, streamlined shape and high specific
gravity will help maintain a low working depth in mild wind and currents. Its compact size and fle ible cable
make it very portable and simple to use. It will interface directly with compact digital recorders and other
devices with mic preamps designed for electret-condenser microphones with 3.5mm input.
Using the H2dM
The H2dM is terminated with a 3.5mm TRS plug and wired for dual-mono output (output wired to
both tip and ring; sleeve contact to ground). The most common application is driving a compact stereo
digital recorder. This output configuration will also work with nearly all video cameras and computer sound
interfaces1 with 3.5mm mic input. Plug-in power (PIP) is required and may need to be swit hed on in
your devi e. When recording with only one hydrophone, direct connection is made to the recorder and
both left and right channels will record the same information. If wanting to record true stereo sound with
two hydrophones, an adapter is typically needed that breaks out the left and right channels of the recorder
into separate input jacks.
Please note that the 3.5mm jack is used for many kinds of audio connections. The H2dM will
only work with mi rophone inputs. The hydrophone plug will fit into au iliary inputs on powered
speakers or marine stereo systems, but these will not provide PIP to the signal conditioning board in the
H2dM, nor will they provide adequate gain. This connector is also used with headphone outputs. Also see
footnote 1 below. Do not make the assumption that, if the plug fits, the system will work.
Hydrophone are
No special care is required for the H2dM. It is designed to withstand corrosion from seawater and
the impact of accidental drops2. Try to keep the output plug clean and dry and avoid unnecessarily rough
handling to ensure the long-term stability of the product. It is best NOT to store the hydrophone in a
waterproof enclosure. Doing so will trap moisture, salts and minerals that are left on the hydrophone and
cable after deployment and prematurely corrode the output plug. Making an e tra effort to coil the cable
neatly when retrieving the hydrophone will help avoid problems with tangles as the cable ages. Most
importantly, protect the cable from cuts and abrasions! The H2dM uses a custom-made cable with a very
durable PU jacket. However, it is also designed to be compact and fle ible. Kinking the cable, walking on
it, or dragging it over a sharp or abrasive surface may damage the cable sheath and eventually cause the
hydrophone to fail. Both aquatic and terrestrial animals may attack the cable in an unattended application.
Using some kind of cable conduit, such as plastic tubing, can help protect the hydrophone in long-term
installations.
1 An adapter will be needed for most headset jacks (TRRS jacks that are designed to have a microphone contact
as well as headphone outputs). These are common on smart phones, tablets and laptop computers.
2 The H2dM uses a plate sensor on the end opposite the cable—somewhat like a microphone diaphragm. It is
e tremely crush-resistant with radial loads, but may be damaged if dropped on its end. It is quite tough for what it
is, but note that it is a sensitive instrument. Avoid throwing it into the water, or any other activity that may result
with an impact to the hydrophone. One great advantage of this design is that it is easy to repair if necessary.
Contact Aquarian for support.

Spe ifi ations
Specifications are dependent upon the audio device to which the H2dM is connected and whether the
hydrophone is driving stereo inputs or a single channel. The output impedance of the H2dM is set by the
PIP supply from the audio device with which the hydrophone is used. Gain of the signal conditioning
amplifier in the H2dM is related to the bias current and input impedance of the mic preamp. High-
frequency performance is also limited by the output impedance of the hydrophone and the cable
impedance—which is a function of length. For all of these reasons, we do not publish detailed response
plots for this design. Please also note that further limitations in your overall system may result from the
sampling rate of digital recorders and by the input stage of your audio device’s microphone preamp.
Note that there is no standard for plug-in power. Performance can vary significantly. The following
specifications are based on typical response when using the H2dM with a compliance voltage of 2.5V and
bias resistor of 1.1K (two channels at 2.2K each—2.2mA—typical of many compact digital recorders,
including those that we sell).
Sensitivity: -172dB re: 1V/Pa (+/- 4dB 20Hz-4KHz)
Useful range: <10 Hz to >100KHz (not measured above 100KHz, appro imate sensitivity
@100KHz = -220dB re: 1V/Pa)
Polar Response: Omnidirectional (horizontal)
Operating depth: <80 meters
Output impedance: 1.1 K(typical)
Power: 0.7 mA (typical)
Minimum PIP req.: 2V, 0.7mA (compliance voltage, short-circuit current)
(the hydrophone will work with lower current, but with
very unpredictable gain and greatly-reduced dynamic range)
Physical: (cable and output plug e cluded)
Dimensions: 25mm 46mm
Mass: 105 grams
Specific Gravity: 5.3
Warranty Statement
Aquarian Audio warrants the H2dM Hydrophone from electrical failure or defects in workmanship for a
period of one year following the date of purchase. Warranty claims or repairs can be made directly through
Aquarian Audio. Corroded output plugs are not covered under warranty. Additional terms and conditions
apply. For full details please view our general warranty statement at
http://www.aquarianaudio.com/warranty.html
Aquarian Audio & S ientifi
A division of AFAB Enterprises
5677 Patricia Lane Anacortes, WA 98221 USA
[phone] www.AquarianAudio.com [e-mail]