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Re: Creating delrin mic supports for SASS

Subject: Re: Creating delrin mic supports for SASS
From: "vickipowys" vpowys
Date: Sun Sep 26, 2010 3:22 pm ((PDT))
Paul,

I am in Capertee Valley which is up towards Mudgee, Central
Tablelands of NSW.

Vicki


On 27/09/2010, at 8:18 AM, thesilverloon wrote:

> Thanks again everyone. Will checkout Clark Rubber and get the ball
> rolling.
> Vicki, can I ask where you are based?
>
> Paul
>
>
> --- In  vickipowys
> <> wrote:
>>
>> Hello Paul,
>>
>> I got my dark grey foam from Clark Rubber.  My nearest store is Dubbo
>> (4 hours drive away) so I had to get it by mail order.  Clarks
>> describe the foam as 'high load' open cell foam.  It seems to be
>> about the same density as the original black foam in my Crown SASS.
>> Clark will cut the foam for you, but they are not always spot on with
>> their right angles or measurements!  Better to buy larger pieces and
>> cut them yourself, use a craft knife.  Extend out a full row of new
>> snap-off blades, and cut carefully along marked lines.  An electric
>> knife would be good but I don't have one.  When you have cut the foam
>> to size and rounded the edges as good as you can with a craft knife
>> and scissors, you can do a final smoothing touch up with very fine
>> sandpaper.  But you need to do all the actual shaping with the craft
>> knife.
>>
>> cheers,
>>
>> Vicki
>>
>>
>>
>> On 27/09/2010, at 6:40 AM, thesilverloon wrote:
>>
>>> 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 cell foams
>>> that I can find have a far higher density than what Rob recommends.
>>> I live in Sydney by the way.
>>>
>>> Paul
>>>
>>> --- In  vickipowys
>>> <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
>
>
>










"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.



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