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Re: Creating delrin mic supports for SASS

Subject: Re: Creating delrin mic supports for SASS
From: "thesilverloon" thesilverloon
Date: Sun Sep 26, 2010 1:40 pm ((PDT))
Hello Vicki,
Can I ask where you sourced the foam for your nosepiece?
The density that Rob suggests does not seem to be easily found. Most open c=
ell foams
that I can find have a far higher density than what Rob recommends.
I live in Sydney by the way.

Paul

--- In  vickipowys <> wrote:
>
> All,
>
> For my various SASS clones I have been making stretchy covers from
> lightweight lycra fabric, which protects the mics from a light breeze =

> and is acoustically transparent.  Over this I use a fine-knitted
> beanie without any high frequency loss that I could detect.  I've
> also tried a loose-knitted mohair scarf, 2 layers of it, which is a
> bit better at wind protection than the beanie and lets through hf.  =

> As Rob says, fur fabric seems to cut out too much hf, I have found
> this as well.
>
> I am just now knitting a large mohair beanie (green!) for a DIY 'fur' =

> cover that is designed to be acoustically transparent.
>
> If you wanted to make something even more windproof you could
> experiment (as Rob has done) with a shield about the size of a large
> hatbox but with fabric sides rather than cardboard.  That way you
> would have say 6 inches of dead air space between the fabric walls
> and the mics.  Maybe try one of those collapsible laundry/ garden
> baskets and re-do the fabric?  Endless possibilities!
>
> Vicki
>
>
> On 25/09/2010, at 3:57 PM, Rob Danielson wrote:
>
> > At 1:42 AM +0000 9/25/10, thesilverloon wrote:
> >>  Rob, thanks for that info.
> >> There's now no good reason not to build one.
> >> Maybe except for one. Wind protection. How well can they be baffled
> >> against the wind?
> >> The original windsock supplied by Crown, would not appear to be that
> >> effective.
> >
> > The stretchy material cover works pretty good until the wind gets
> > into 15+ mph range.  Vicki Pows adds a wooly layer to the stretchy
> > material she can comment about. A single layer of burlap in a full
> > surround of dead air is working pretty well for me up to about 25-30
> > mph. I couldn't get fake fur to work in proximity to the SASS body
> > without too much HF loss. Rob D.
> >
> >   =3D =3D =3D
> >
> >
> >> I would be mounting my AT 4022'S into this setup if I were to
> >> build one.
> >>
> >> Paul
> >> --- In
> >> <naturerecordists%
> >> 40yahoogroups.com>
> >> Rob Danielson <type@> wrote:
> >>>
> >>>  Hi Paul--
> >>>  Can one make a baffle using high-density foam that will provide
> >>>  comparable or indistinguishable performance? Its definitely doable.
> >>>  There are several types of high-density, _open cell_ foam out
> >>> there.
> >>>  I tested four or five kinds and found they did pass pink noise with
> >>>  very slight differences. A neat aspect of foam baffle is it cleanly
> >>>  passes some sound energy under < 1100Hz to the off-side mic. These
> >>>  frequencies are critical for time arrival differences. Michael
> >>>  Billingsley doesn't mention this aspect of the baffle in his SASS
> >>>  patent as far as I can tell. Would different types of foam make
> >>>  audible differences? All we need to do is make some up and compare
> >>>  them to find out.
> >>>
> >>>  Cutting and sanding the foam to fit snuggly into the crown housing
> >>>  would take some time. Vicki Powys discovered that sanding is a good
> >>>  way to get the final shape and dimensions.
> >>>
> >>>  Any open cell foam that has a density of 1.5 to 1.8 pounds per
> >>> cubic
> >>>  foot and is at least 4 inches thick should perform to Billingsley's
> >>>  high frequency absorption specifications. I use "charcoal gray"
> >>>  acoustic foam. A 10" X 10" X 4" piece should be sufficient to make
> >>>  a SASS baffle replacement. Measure twice, cut once. Rob D.
> >>>
> >>>  =3D =3D =3D =3D
> >>>
> >>>  At 11:27 PM +0000 9/24/10, thesilverloon wrote:
> >>>> Does anyone know how important using the correct foam for the
> >>> nose piece is?
> >>>> One can buy just the foam nose piece from Crown as a spare part, =

> >>>> and
> >>>> then build the rest.
> >>>> Thats still $100 landed in Australia. But if any closed cell foam
> >>>> would work,that would make the project that more do-able.
> >>>>
> >>>> Regards,
> >>>>
> >>>> Paul
> >>>
> >>>
> >>>  --
> >>>
> >>
> >>
> >
> >
> > --
> >
> >
> >
> >
> >
> > ------------------------------------
> >
> > "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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