計測機器 Aquarian Audio Products H3nPのPDF ユーザーマニュアルをオンラインで閲覧またはダウンロードできます。Aquarian Audio Products H3nP 2 ページ。 Hydrophone

H3 product family overview

The H3 uses a unique high-sensitivity, dual-sensor, mechanically-balanced transducer assembly that

offers exceptional signal-to-noise performance in the human auditory bandwidth. The fully-shielded design

inherently rejects EMI and RFI noise, making it useful in the studio, lab or shop. Its low mass and full polyurethane

rubber encapsulent make it highly resistant to damage caused by impact. Its small size allows users to fish it

inside of pipes and other tight spaces, making it excellent for leak finding. Though designed primarily for

underwater listening and leak finding, it is also useful as a waterproof microphone for tool room applications, such

as monitoring cutting in waterjet and other CNC tooling

The H3nP and H3nB are sold as passive hydrophones, terminated with 1/4" TS and BNC output plugs

respectively. These can be useful with DAQ and test equipment or high-impedance audio preamps. H3dM and

H3dX configurations include signal conditioning that is built into the hydrophone, which make them compatible with

standard consumer and professional microphone circuits. They are identical, other than the output connector. The

"n" in the part number designates the signal conditioning board used—in this case, none. The piezo sensor array

is connected directly to the cable. Please reference correct manual for each version.

The H3 hydrophone can be optionally assembled with our WT150g sliding stainless steel weight assembly

for maintaining negative buoyancy. There are several advantages to placing the weight on the cable, rather than

building it into the hydrophone. When the hydrophone is dropped, the cable flexes and absorbs any stress from

impact, making the hydrophone more durable. The weight can be moved if needed to allow insertion into a pipe.

Both of these attributes are especially useful to the leak finding specialist. Moving the weight away from the

hydrophone dampens acceleration noise that is transmitted down the cable from handling and it also minimizes

response irregularities caused by material resonances and sound reflections. It can also be used for mounting a

shroud tube to minimize flow noise over the hydrophone. To move the WT150g weight, turn the black plastic

thumbscrew counter-clockwise to loosen the internal rubber compression sleeve and slide the weight where

needed. Wet the cable if this is difficult. Secure again by turning the thumbscrew clockwise. Be Advised: Finger-

tighten thumbscrew only and always leave a minimum spacing of 5cm (2 in.) between hydrophone and weight!

Using the H3n

When using a passive piezo sensor, input impedance of the hydrophone preamp should be considered.

Impedance is the load that your preamp puts on the hydrophone. The low-frequency response of a piezo

transducer, such as that used in the H3, will be limited by the input impedance of the preamp. Higher input

impedance will result in extended low-frequency response. Very low frequency response can be troublesome

because it is most often noise from acceleration or thermal change, or sound that is dominated by machinery, so it

is often desirable to filter low frequency using the input impedance of your amplifier. If your hydrophone response

is unstable (seems to be cutting out) it is very possible that you are saturating the input of your preamp with

infrasound.

This relationship can be calculated for the H3 with the following formula: Fc = 1 / 0.000000094 * R

Fc is the frequency at which electrical output is 3dB below nominal and R is the input impedance of your preamp,

measured in ohms (Ω). Therefore, using a preamp with an input impedance of approximately 500 KΩ will give you

a low-frequency cutoff of 20 hertz—the low end of what humans can hear. Many high-impedance audio preamps

have input impedances of 1MΩ or more. Test equipment, such as oscilloscopes and spectrum analyzers have

typical input impedances of 10MΩ or more.

Aquarian does not guarantee compatibility of rubber and plastic materials used in its hydrophones for anything other than natural aquatic

environments. Prospective users should test compatibility with machine coolants and lubricants in production environments.

Aquarian Audio

H3n Hydrophone User's Guide