Hi Vicki
That's interesting, and surprising. I, too, expected the nose foam to be more
dense. I am currently using about a 4cm thick piece of the #1 foam on top of
the mic capsules as a wind baffle, and it seems to be pretty much acoustically
transparent. Is the nose baffle only attenuating some frequencies, or none at
all? Is it thick enough that it separates the channels even though it is fairly
transparent?
I guess what I am using in my prototype (my foam #4) is probably low or medium
density closed cell foam. I guess, but I don't know! It is not absorbent, it is
fairly but not extremely rigid, and the cells are large. Lots of air space, but
the plastic cell walls are fairly rigid. And I added some cardboard around that
to create even more separation between the two channels. I rather like the
image it produces (airplane noise aside), which is what matters in the end, but
it sounds like that is not the intent of the Crown SASS. What is the theory?
What is acoustically separating those two omni capsules?
If this has all been explained in detail somewhere, can you provide a link to
that discussion?
Unfortunately I am not aware of any foam supply stores anywhere in New England.
I've tried searching online and I'm just not sure what I am looking for. This
is the sort of thing I find online:
http://www.onlinefabricstore.net/specialty-stores/automotive-store/automotive-upholstery-padding-and-supplies/automotive-upholstery-foam/open-cell-foam/high-density-open-cell-foam.htm?N=11774+4294963398
This looks a lot like my foam #2 - the mattress foam, but it's hard to tell
looking at pictures online. Is this what I want?
I wish someone could send me a tiny sample of the right stuff so I know what it
looks and feels like. Then I could go to a fabric and upholstery store and see
if they have it. Please contact me off list if that is possible! I'll pay
postage!
Many thanks! (Sorry for all the exclamation marks but I am truly grateful to
everyone who contributes to this fascinating and informative group).
John
--- In vickipowys <> wrote:
>
> John,
>
> You would need to go to a foam supply store, rather than a building
> store. In Australia we have Clark Rubber chain stores who specialize
> in foam, not sure who does in US.
>
> You can tell if it is open cell if the foam absorbs water like a sponge.
>
> The idea in the original SASS design is that some sound can pass
> through the open-cell foam. However I know of several people who, in
> misunderstanding the SASS design, have built the front 'nose' out of
> something solid e.g. closed cell foam or balsa-wood. And the sounds
> samples I have heard are just great, so perhaps it does not matter
> hugely.
>
> I would say that your number 1) would be most like the open-cell foam
> used for the nose of the original SASS.
>
>
> Vicki Powys
> Australia
>
>
>
> On 09/07/2012, at 7:01 AM, John Crockett wrote:
>
> > 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 insulating our cellar). Sort of similar to styrofoam.
> >
> > 4) Finally I have sort of an odd thing that came as cushioning
> > material in a box with an electronic device. It is rigid, like the
> > blue board, but the cells are much larger than that in the blue
> > board and therefore it is a bit 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 thing (built for AT3032 mics), I'd like to get it right.
> >
> > Many thanks!
> >
> > John
> >
> > John Crockett
> > Westminster, Vermont
> >
> > --- In Peter Shute <pshute@>
> > 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, and 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 left it behind after bringing a piece in
> >> for cutting, and let me have it for $3.
> >>
> >> There's something a bit disturbing about an industry that's
> >> inconsistent 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: <naturerecordists%
> >>> 40yahoogroups.com>
> >>> <naturerecordists%
> >>> 40yahoogroups.com>] On Behalf Of vickipowys
> >>> Sent: Tuesday, 28 February 2012 8:54 AM
> >>> To: <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: <naturerecordists%
> >>>> 40yahoogroups.com><naturerecordists%
> >>>> 40yahoogroups.com>
> >>>> <naturerecordists%
> >>>> 40yahoogroups.com><naturerecordists%
> >>>> 40yahoogroups.com>] On Behalf Of vickipowys
> >>>> Sent: Tuesday, 28 February 2012 8:06 AM
> >>>> To: <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: <naturerecordists%
> >>>>> 40yahoogroups.com><naturerecordists%
> >>>>> 40yahoogroups.com><naturerecordists%
> >>>>> 40yahoogroups.com>
> >>>>> <naturerecordists
> >>>>> %40yahoogroups.com><naturerecordists%
> >>>>> 40yahoogroups.com><naturerecordists%
> >>>>> 40yahoogroups.com>] On Behalf Of hartogj
> >>>>> Sent: Tuesday, 28 February 2012 7:19 AM
> >>>>> To: <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 <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
> >>>>>>
> >>
> >>
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> > ------------------------------------
> >
> > "While a picture is worth a thousand words, a
> > sound is worth a thousand pictures." R. Murray Schafer via Bernie
> > Krause.
> >
> > Yahoo! Groups Links
> >
> >
> >
>
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