Hi, I found some types of open cell foam sold in blocks to make filters for
acquaria; the type I found are not very soft and have open cells up to 2-3
mm in diameter. We use them to protect hydrophones as they don't hold air
bubbles. However I never tested them to verify their acoustic properties
in air and their efficacy against wind.
Gianni
2012/7/8 John Crockett <>
> **
>
>
> If I can re-open this thread,
>
> I'm still unclear about exactly what high-density open-cell foam is. My
> local building supply store hasn't a clue.
>
> I have several types of foam lying around the house.
>
> 1) One is very soft and pliable, like the foam windscreens that come with
> most microphones. It came as packing material.
>
> 2) Another is a bit denser and thicker, the sort of foam that is used for
> mattresses.
>
> 3) Then we have what in the USA is called blue board. This is a very
> dense, small cell, rigid foam that comes in sheets of various thicknesses
> and is used for building insulation (we have some left over from insulati=
ng
> our cellar). Sort of similar to styrofoam.
>
> 4) Finally I have sort of an odd thing that came as cushioning material i=
n
> a box with an electronic device. It is rigid, like the blue board, but th=
e
> cells are much larger than that in the blue board and therefore it is a b=
it
> springy when pressed. It is not as rigid as styrofoam.
>
> 5) Oh, and somewhere I have a block of stiff, small-celled foam that is
> used to go between a kayak or canoe and the roof of the car.
>
> Are any of these "high-density, open-cell" foam? If not, what does this
> creature look and feel like?
>
> I built a prototype sass array using EM172 capsules, and #4 above for the
> nose baffle, and it works well as far as I can tell, but for the real thi=
ng
> (built for AT3032 mics), I'd like to get it right.
>
> Many thanks!
>
> John
>
> John Crockett
> Westminster, Vermont
>
>
> --- In Peter Shute <> wrote:
> >
> > I made it to Clark Rubber tonight, and sure enough it wasn't as I
> expected. According to this store, high density foam comes in colours, an=
d
> acoustic foam is grey and only 2" thick.
> >
> > Then I spotted a light grey scrap in a bin, exactly the size I wanted,
> but twice as long. It felt like the acoustic foam, so I think it's the
> right stuff. They weren't sure what it was and thought a customer had lef=
t
> it behind after bringing a piece in for cutting, and let me have it for $=
Message: 3.
Subject: > >
> > There's something a bit disturbing about an industry that's inconsisten=
t
> about what it calls its products.
> >
> > Peter Shute
> >
> >
> > --------------------------
> > Sent using BlackBerry
> >
> > ________________________________
> > From:
> > To:
> > Sent: Tue Feb 28 10:17:03 2012
> > Subject: Re: [Nature Recordists] Re: Foam for SASS
> >
> >
> >
> > Peter,
> >
> > re filling inside of SASS box - well I've overcome that problem by
> > making my SASSes out of solid blocks of closed-cell foam (it's
> > lighter weight too) - see my website. If you've made a wooden SASS
> > you could fill the gap with closed cell foam.
> >
> > Vicki
> >
> > On 28/02/2012, at 9:08 AM, Peter Shute wrote:
> >
> > > Excellent, if I can tell by colour then they can't trick me. It
> > > sounds pretty cheap, so I'll get enough for future experiments.
> > >
> > > Can you recommend what to fill the inside of the box with?
> > >
> > > Peter Shute
> > > ________________________________
> > > From: <mailto:
> naturerecordists%40yahoogroups.com>
> > > <mailto:
> naturerecordists%40yahoogroups.com>] On Behalf Of vickipowys
> > > Sent: Tuesday, 28 February 2012 8:54 AM
> > > To: <mailto:
> naturerecordists%40yahoogroups.com>
> > > Subject: Re: [Nature Recordists] Re: Foam for SASS
> > >
> > >
> > >
> > > Yes Peter, Clark Rubber call their stuff 'high density foam' and it
> > > is grey in colour (as opposed to medium density foam which comes in
> > > many colours). The acoustic foam is black. My nearest Clarks used
> > > to be at Bathurst (2 hours away) but they closed and now I have to
> > > get it via mail order from Dubbo where they can never cut it
> > > straight. I agree Clark's website is pretty useless. If you can get
> > > Clarks to cut it in blocks around the size you want, you can then
> > > taper the sides according to Rob's specifications, using a razor
> > > knife with a new blade extended all the way out. And tidy up the cut
> > > surfaces with a little piece of fine sandpaper.
> > >
> > > Vicki
> > >
> > > On 28/02/2012, at 8:17 AM, Peter Shute wrote:
> > >
> > >> Thanks, Vicki. You mean the one they're calling high density but
> > >> which isn't acoustic foam? If that works then it would be better
> > >> not to have to glue it.
> > >>
> > >> It's a pity I can't see the stuff on their web site before I go
> > >> there, or even just order it online to save myself the trouble, but
> > >> the web site is a mess. A search for high density foam takes me to
> > >> anything but what I expect to see.
> > >>
> > >> Peter Shute
> > >>
> > >> ________________________________
> > >> From: <mailto:
> naturerecordists%40yahoogroups.com><naturerecordists%
> > >> 40yahoogroups.com>
> > >> <mailto:
> naturerecordists%40yahoogroups.com><naturerecordists%
> > >> 40yahoogroups.com>] On Behalf Of vickipowys
> > >> Sent: Tuesday, 28 February 2012 8:06 AM
> > >> To: <mailto:
> naturerecordists%40yahoogroups.com><naturerecordists%
> > >> 40yahoogroups.com>
> > >> Subject: Re: [Nature Recordists] Re: Foam for SASS
> > >>
> > >>
> > >>
> > >> Peter,
> > >>
> > >> I have always used the grey high-density foam from Clark Rubber,
> > >> which is fairly close in texture to the original foam that was used
> > >> in the Crown SASS design. And you won't have to glue either.
> > >>
> > >> Vicki
> > >>
> > >> On 28/02/2012, at 7:28 AM, Peter Shute wrote:
> > >>
> > >>> Good enough for me then. I'll try to get there tonight and get some
> > >>> of the acoustic foam.
> > >>>
> > >>> The plans also say to fill the void with "dense absorptive material
> > >>> like rubber backed carpet padding". Does that mean similar material
> > >>> to that used for the baffle? I.e. can I just get a bit more of it
> > >>> to put in there?
> > >>>
> > >>> Peter Shute
> > >>>
> > >>> ________________________________
> > >>> From: <mailto:
> naturerecordists%40yahoogroups.com><naturerecordists%
> > >>> 40yahoogroups.com><naturerecordists%
> > >>> 40yahoogroups.com>
> > >>> <mailto:
> naturerecordists%40yahoogroups.com><naturerecordists%
> > >>> 40yahoogroups.com><naturerecordists%
> > >>> 40yahoogroups.com>] On Behalf Of hartogj
> > >>> Sent: Tuesday, 28 February 2012 7:19 AM
> > >>> To: <mailto:
> naturerecordists%40yahoogroups.com><naturerecordists%
> > >>> 40yahoogroups.com><naturerecordists%
> > >>> 40yahoogroups.com>
> > >>> Subject: [Nature Recordists] Re: Foam for SASS
> > >>>
> > >>>
> > >>>
> > >>> Hi Peter,
> > >>> The open cell foam in the nose baffle is part of the original Crown
> > >>> SASS design, and that design has proven good for natural soundscape
> > >>> recording. I think the reason for sticking with the open cell
> > >>> design is mostly for the sake of consistency. Some low frequencies
> > >>> will pass through the foam nose, some frequencies are absorbed, and
> > >>> some will be reflected. The qualities of these transitions will
> > >>> depend on the specific material used.
> > >>>
> > >>> John Hartog
> > >>> rockscallop.org
> > >>>
> > >>> --- In <mailto:
> naturerecordists%40yahoogroups.com><naturerecordists%
> > >>> 40yahoogroups.com><naturerecordists%
> > >>> 40yahoogroups.com><naturerecordists%
> > >>> 40yahoogroups.com>, Peter Shute <pshute@> wrote:
> > >>>>
> > >>>> I'm building a SASS array to Rob Danielson's design (https://
> > >>>> pantherfile.uwm.edu/type/www/audio-reports/BoundaryMicExperiments/
> > >>>> images/PBB2N-Plans_SASS-LikeDimensionsSept2010.gif), and I have
> > >>>> some questions about the foam used for the nose (baffle?)
> > >>>>
> > >>>> The plans say to use high-density open-celled foam, and I don't
> > >>>> know how to identify the stuff. I rang the local supplier (Clark
> > >>>> Rubber, which Australians would know), and they said they can cut
> > >>>> a piece for a few dollars. But when I mentioned what it was for,
> > >>>> they said it would be better to use acoustic foam, which doesn't
> > >>>> cost much more.
> > >>>>
> > >>>> They said it's similar, but denser. It also comes in thinner
> > >>>> sheets, so I'd have to glue two pieces together.
> > >>>>
> > >>>> Will it be better. Does it even matter?
> > >>>>
> > >>>> If the aim of the foam is to block sound from the other side, why
> > >>>> open cell? Does it work better for that?
> > >>>>
> > >>>> Sorry if these are basic questions, I don't know anything about
> > >>>> foams, their acoustic properties, and how this array works.
> > >>>>
> > >>>> Peter Shute
> > >>>>
> >
> >
> >
> >
> >
> >
>
>
>
--
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Universit=E0 degli Studi di Pavia
Via Taramelli 24, 27100 Pavia
http://www.unipv.it/cibra
http://mammiferimarini.unipv.it
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