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Re: hydrophone construction

Subject: Re: hydrophone construction
From: "jasonpudd" jasonpudd
Date: Mon Jun 1, 2009 2:51 pm ((PDT))
Patrick,

>From a practical perspective only, I am not the best person to ask technically 
>about sound engineering but maybe someone else is in the group.  If you used 
>an air filled enclosure like this where I am from (British Columbia) you would 
>have considerable build-up of condensation.  This is caused by the colder 
>temperature of the water in relation to the ambient above water.  You may 
>develop some problems with the unit due to this.  If you had a small leak, 
>even a drop, and this went un-noticed even for a short time, this would cause 
>considerable corrosion from the salt water.  Up here we pack our underwater 
>stobe connections with silicon to stop this from happening and shorting our 
>the contacts and causing corrosion.  This works really well.  The same problem 
>happens in other climates with cold water temperatures.

Jason

--- In  ". m u r m e r ." <> wrote:
>
> and while i'm out of lurk mode...
> 
> i posted this question to the phonography list, but got no response, so 
> i thought i'd try here.  any thoughts about this?
> 
> i've been fiddling with building a simple hydrophone for awhile now.
> i'd made several attempts with hollow cavities filled with vaseline,
> poster tack, oil, or nothing.  i'd read that a hydrophone ought to be
> filled with oil, something about it having a similar density to water
> and therefore letting the soundwaves travel through the cavity to the
> piezo inside.  working with oil is messy, however, and it's very
> difficult to reliably seal the cavity without any air bubbles inside.  i
> managed one though, but i also had an identical one which i'd sealed
> with an empty cavity.  i compared them, and both work great, and sound
> remarkably similar, if not identical.  so what i wonder is: why do i
> think the cavity needs to be full of oil?  what does that provide that
> my empty one does not have?  anyone have any insight?
> 
> best,
> patrick
> 
> -- 
> 
> |||  www.murmerings.com |||
>








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