From: <>
>
> Olivia,
>
> I found the following list of available hydrophones:
> http://www.dal.ca/~whitelab/marmam/hp.htm
>
> The great news is that there are a variety of hydrophones listed in a
> variety of price ranges. Unfortunately, apparently a lot of them require
> some sort of charge amplifier to convert the signal to something useful.
> That is why phantom power would seem to be a good thing. Getting a
> high-impedance device like a hydrophone to work while immersed in salt
> water, and to keep working, must be a tough engineering job. If you were to
> make it battery powered, then that implies that you would have to be able to
> open it up and that implies an entrance for corrosive salt water...
>
> Eric
>> Heres a dumb question-why is the phantom power so important? Simply
>>because you dont want to use a battery under water?
Both the hydrophones I have pass the battery power down the cable from a
power box that's not immersed. The power box could be a small pelican
box and thus waterproof, though mine are not. You do not open up a
hydrophone, they are made and permanently sealed typically. The cable is
of course sealed with them. Everything to and from then goes via the cable.
For a inexpensive hydrophone, look into places associated with whale
watching. That has resulted in a number of low cost hydrophones,
typically with a headphone amp and a output to a recorder. One I have
like that is from:
http://www.aquarianaudio.com/
I have that entire hydrophone system (long cable version) along with a
miniplug to XLR adapter cable stored in a Pelican 1060 case. I got it
off ebay this year and have not had a lot of opportunity to use it yet.
Seems to work fine.
Phantom power is more important because it's the power used in pro
equipment. As you move up in mics you find plenty that only work with
phantom power. So, having it available removes a equipment limitation.
Phantom power is also associated with balanced cables. These are far
less likely to pick up interference and send it into your pre. This is
not a big issue in nature recording where we are generally fairly far
for sources of interference. However another thing about balanced cables
is that they usually allow longer cable runs, which can be a issue in
some nature recording.
There is a lot to say for not having a variety of battery powered
equipment. Using all phantom powered gear means you only have to support
your recorder, which uses it's battery to power the mics. I find this
does not use enough battery power to be a problem, and the convenience
of just plugging in any of my mics without worrying about their
batteries is well worth it.
Walt
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