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Re: contact mic (OT)

Subject: Re: contact mic (OT)
From: "Greg Weddig" gweddig
Date: Sat Oct 14, 2006 2:45 pm (PDT)
On Broadway for shows with tap dance, in addition to putting a
wireless mic on each shoe, the stage can be covered in plywood panels
with contact mics on the underside of the panel.  Now mind you this is
a complex floor assembly to support the needs of the show and in my
recollection they ended up using more of the foot mics than the
under-floor mics.

Of course I have no idea what it would sound like with sand on it, I
would imagine "squeaky" (small grains?) or "crunchy" (bigger grains?)
would help transmit the sound to the contact mics.  The sand layer
would need to be deep enough so audience members would not bottom out
on the substrate.
I would suggest doing a mockup with a few different materials, seeing
which sounds the best.  It will have to support the weight of the sand
and the people, you might want to talk to a flooring
contractor/installer for advice.
Try rubber cement on the mics, make sure it doesn't eat away at the
mic material.  I used thin double stick tape, not the foam stuff, when
attaching contact mics to large (5' x 10') sheet metal for thunder
effects in opera.

--greg weddig
Baltimore, MD
http://www.ourmedia.org/user/627
http://home.earthlink.net/~gweddig



--- In  "faza.rm" <> wrote:
>
> 
> Hello all..
> 
> I have one quick question about the contact mics...
> I was trying to use metal sheets to fix the mics on to get the best
sound possible.. now to 
> cover such a large area with sheet metal was too expensive for me..
i was wondering if 
> there is another material that would be ideal for contact mics.. i
gather wood would absorb 
> the sound vibrations too much.. 
> any suggestion would be much appreciated...
> 
> thanks
> 
> 
> --- In  "faza.rm" <faza@> wrote:
> >
> > Thank u all for the reply...
> > 
> > OK here is where i am at right now..
> > I have got metal sheets to fix the contact mics.. the size of the
sand pile is about 10ft x 
> 10 
> > ft and i have got circular arrays of about 200 contact mics...the
idea is to increase the 
> > audio level as the viewer walks closer to the subwoofer.. so each
array is connected to a 
> > mixer...
> > My question is what would be the best glue to fix the contact mics
to the metal sheet?? 
> > aslo do u think i should keep the metal sheet lifted off the floor
to get maximum 
> > vibration.. for some reason this gallery has carpeted floor so i
am thinking it might 
> absorb 
> > the vibration.. 
> > anyways i will keep this updated as i go along.. 
> > again.. i do appreciate the feedback,,
> > thanks
> > 
> > 
> > 
> > --- In  "Aaron Ximm"
<aaron.ximm@> wrote:
> > >
> > > On 9/30/06, faza.rm <faza@> wrote:
> > > >
> > > > I am doin this installation for a gallery. There will be a
subwoofer inthe
> > > > middle of the gallery
> > > > and a pile of sand around it.. the viewers are required to
walk on the
> > > > sand..
> > > > I am trying to buy contact mics and burry them in the sand so
that the
> > > > sounds of their
> > > > footstep will be picked up and transmitted to the speaker...
> > > > However the contact mics that  i got does not seem to be as
senstive as i
> > > > thought it would
> > > > be.. i am just fixing them onto the floor..
> > > 
> > > 
> > > This a great question for the phonography and perhaps
lowercase-sound
> > > mailing lists, where more people do this kind of work...
> > > 
> > > I would first try bonding the mics to a large thin sheet of
metal and put
> > > the sand over that. A tight coupling will let the sheet act as
one large
> > > sensative receptor. You still may find you need a lot of gain
however.
> > > 
> > > Australian sound artist Joel Stern told me recently about an
altoids-tin box
> > > he got as a direct-in (DI) box for using piezoelectric contact
mics, he
> > > called it a preamp but I was wondering if was doing impedance
matching since
> > > it changed the frequency response of his piezos. He got it from
someone
> > > online for around US$25, but I don't remember what they're
called, alas.
> > > 
> > >  best,
> > >   aaron
> > > 
> > > -- 
> > >   aaron.ximm@
> > >   quietamerican.org
> > >   oneminutevacation.org
> > > 
> > >   83% happy
> > >    9% disgusted
> > >    6% fearful
> > >    2% angry
> > > 
> > > 
> > >
> >
>







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