John,
I am not sure about the green stuff. I have been using scrap material as I =
can scrounge it up for free - stuff that seem similar to a piece of foam I =
got from Rob Danielson back a while ago when he had some surplus to share.
I had done some searching around my town, Portland Oregon, and this is what=
I found:
A1 Foam Rubber, sells a dark gray open-cell foam they call "J-90 Char" They=
sell it at $4 US per board foot as calculated H"xW"xL"/144.
Grainger, also sells a dark grey open-cell.
http://www.grainger.com/Grainger/Foam-Sheet-5GCP5?Pid=3Dsearch
Not sure what they charge for shipping, but it looks like they have a branc=
h in South Burlington, VT if that is near you.
John Hartog
rockscallop.org
--- In "John Crockett" <> wrote:
>
> Hi Vicki,
>
> The foam I am able to find locally is green (whatever that means!). It is=
called high-density foam (they also sell "regular" density, which is white=
), and although the clerks in the store had no idea about open or closed ce=
ll, it is absorbent like a sponge, so I guess it is open-cell. It isn't nea=
rly as dense as I expected, less so, I think, than the foam mattress pad I =
mentioned. It is quite squishy. The 4" x 6" x 9" scrap I bought weighs 125 =
grams.
>
> Could I possibly have the right thing? I can return it if I bought the wr=
ong material, but how can I tell? Does anyone know?
>
> Many thanks,
>
> John Crockett
> Westminster, Vermont
>
> --- In vickipowys <vickipowys@> wrote:
> >
> > Hi John (& John),
> >
> > I looked at your link John C, all the foam they make seems to be
> > white. I recall Rob Danielson found a US source that had 'High
> > Density Open-cell Foam' that was dark grey in colour, the colour was =
> > the way of identifying the type of foam i.e. different colours for
> > different types of foam. You should not need to buy a whole sheet of =
> > it, there must be a foam place that will custom cut it. At one time =
> > Rob was sending out blocks of grey foam to anyone who wanted it.
> >
> > The foam you are after should not be at all heavy, I note that some =
> > of the more dense foams are actually quite heavy.
> >
> > I agree with everything John H has said about the claims made by
> > Crown, I don't think anyone really quite knows what goes on. But it =
> > is logical that high frequency sounds would be more easily blocked by =
> > the foam, than would low frequency sounds.
> >
> > Don't forget that the (metal) wrap around the foam also blocks
> > sound. The original Crown was made of plastic but the blocking
> > effect would be the same.
> >
> > Vicki Powys
> > Australia
> >
> >
> >
> >
> > On 10/07/2012, at 5:07 AM, hartogj wrote:
> >
> > > Hi John
> > >
> > > Yes, it has been discussed before on this list, but before you
> > > search the archives have a look at Rob Danielson's boundary mic
> > > blog at:
> > > http://diystereoboundarymics.blogspot.com/
> > >
> > > I seem to recall a Crown description of the SASS saying that the
> > > low frequencies pass around the array and through the nose in a way =
> > > that sum thus boosting the low end a bit. This balances those lower =
> > > frequencies with the higher frequencies that are amplified by the =
> > > boundary plates, and provides a flatter overall frequency
> > > response. Disclaimer: I am probably not remembering that
> > > accurately, and even if I am, it may have just been Crown marketing =
> > > hype.
> > >
> > > John Hartog
> > > rockscallop.org
> > >
> > >
> > > --- In "John Crockett"
> > > <jladd@> wrote:
> > >>
> > >> 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=3D11774
> > >> +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 <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 o=
f
> > >>> something solid e.g. closed cell foam or balsa-wood. And the sound=
s
> > >>> 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 b=
y
> > >>>>> 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 SAS=
S
> > >>>>> 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 use=
d
> > >>>>>> 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 the=
n
> > >>>>>> 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 bu=
t
> > >>>>>>> which isn't acoustic foam? If that works then it would be bette=
r
> > >>>>>>> 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>
> > >>>>>>> <naturerecordist=
s
> > >>>>>>> %
> > >>>>>>> 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>
> > >>>>>>>> <naturerecordis=
t
> > >>>>>>>> s
> > >>>>>>>> %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 wil=
l
> > >>>>>>>> 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
> > >>>>
> > >>>>
> > >>>>
> > >>>
> > >>
> > >
> > >
> > >
> > >
> > > ------------------------------------
> > >
> > > "While a picture is worth a thousand words, a
> > > sound is worth a thousand pictures." R. Murray Schafer via Bernie =
> > > Krause.
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> >
>
|