From: julie freeman <>
>
> Hello,
>
> I'm looking to record some underwater and underground sounds from a
> fishery in Bedfordshire, UK.
>
> On a limited budget I have found these hydrophones that I thinnk will
> do the job adequately:
>
> http://www.dolphinear.com/pro/pro-specs.htm
>
> Frequency Response (Overall): 15 Hz - 20,000 Hz +/- 3db
> Hydrophone Transducer Type: MPC (Piezo) High output
> Configuration: OmniDirectional, BALANCED OUTPUT, 600 ohms XLR
> Hydrophone Packaging: Rugged epoxy case, 60mm Dia x 8 mm Thick
> Cable Type: High Quality, Low Noise, Neoprene/PVC jacket for long life
> Cable Length: 10 metres (standard); special orders to 100m lengths.
> Output Connector: Standard 3 pin XLR
> Power: NONE, does NOT require phantom power - compatible with equipment
> that provides up to 48v of phantom power on the balanced leads.
The Dolphinear I tried was the regular, not the new pro. And some time
back now so it may have been a earlier model.
It's problem was the shielding was not good enough. It would pick up
local radio stations anytime I tried to use it. From the moment it
entered the water. With nearly a pound of magnetic chokes on it I could
make out other things but not completely eliminate the radio stations. I
was using it in fresh water.
I contacted the company and they admitted that they'd had some problems
with it picking up ships radio on the ocean. They are the ones that
suggested the magnetic chokes.
You'd want to make sure that problem was fixed or else avoid the Dolphinear=
.
I replaced it, with the similar Aquarian hydrophone system (gotten used
off ebay)
http://www.aquarianaudio.com/products.htm
This does not have the radio pickup problem. It's a ok hydrophone.
Recently I acquired a Cetacian Research C13 hydrophone. I've not really
had a chance to give it a good test yet, waiting the gopher frogs
calling. So far it sounds good.
http://www.eskimo.com/~cetacean/hpinfo.html
> My question is: I think I will need a pre-amp - what do I look for
> when purchasing one of these?
Many hydrophones have a built in preamp. Or will work with regular audio
inputs. I plug the outputs from mine directly into the Portadisc mic
inputs. Or line inputs if using the headphone out of the earlier ones.
Walt
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