omichalis
Date: Thu Jul 22, 2010 9:37 am ((PDT))
I have a different experience with the dolphin ear pros
they can even act as open-air transducers if you apply enough gain..
Once I had the gain high enough and I could hear my own voice through them.=
.
I did a test with double-sided tape and stick them in the walls of my house=
once - and I had excellent results ! i could hear people walking two floor=
s up !
m
On 21 =CE=99=CE=BF=CF=85=CE=BB 2010, at 9:17 =CE=BC.=CE=BC., Robb Nichols w=
rote:
> On 7/21/2010 5:20 AM, davimon100 wrote:
> >
> >
> > Am I right in thinking that hydrophones are waterproof contact
> > microphones? If so, it should be possible to hook a contact mic up to
> > pick up surface vibrations on an object outside of water, right?
> >
>
> I think that the term "contact mic" can mean different things to
> different people. To many, they think of a contact mic as a little brass
> piezo bender disk. I suspect that this is what you are referring to.
> These need to be flexed in order to generate significant output and work
> in different modes of operation as contact mics. If bonded tightly to a
> surface, they pick up only ripples resonating across the surface of
> whatever you are trying to record. If they are pushed onto an uneven
> surface, or the disk is supported around its perimeter, it can also more
> effectively pick up the motion of the object in space perpendicular to
> the disk. In this case it is working more like an accelerometer.
>
> A hydrophone is a dynamic pressure transducer, similar to an omni mic.
> They can be made from these piezo disks, but I wouldn't say that they
> are the same. I don't know how your Dolphin Ear hydrophone is made, but
> it looks and sounds like it uses at least one large piezo bender disk.
> If this is the case, it might need to be flexed to generate a signal.
> The epoxy potting material around the sensor will stiffen this up and
> dampen its sensitivity. It should be designed to pick up pressure
> differences, so it might be helpful to put something massive behind it.
> Obviously, caution is essential not to break the hydrophone. You
> certainly wouldn't want to do this with a hydrophone made from a
> spherical of cylindrical piezo transducer.
>
> Regards, Robb
>
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause
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