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1. Re: parabolic mics

Subject: 1. Re: parabolic mics
From: "Jose Freitas" =
cketmail.com
Date: Fri Jun 17, 2011 1:32 am ((PDT))

Ok,

You must refer to the exell the diameter was 61cm,increment 3cm, number of =
raws 10, sections 14 focus 15cm focal reason 0,25
profundity 15,5cm.
Good work,
Jos=E9

--- In  Peter Shute <> wrote:
>
> Thanks for that. What diameter and focal length did you use?
>
> Apologies for hijacking this thread.
>
> Peter Shute
>
>
> --------------------------
> Sent using BlackBerry
>
> ________________________________
> From: 
> To: 
> Sent: Thu Jun 16 22:48:03 2011
> Subject: Re: [Nature Recordists] parabolic mics
>
>
>
> Hello,
> I have used this exel
> http://graffiti.virgin.net/ljmayes.mal/var/parabola.htm
>
> after computation you make your elements in hard papel, you connect the e=
lements toghether with tesa film you chose a place with sand and you put th=
e paper parabola sustained by the sand. After that you make with water and =
clay a soup, you put the soup in the parabola for one day. With a knife and=
 sand paper you makes a good mold. After that you puts the fiber glass, two=
 times at least but you can make the parabola as thik as you like it.
> Good job,
> Best regards,
> Jos=C3=A9
>
>
> --- In <naturerecordists%40yahoogr=
oups.com>, Peter Shute <pshute@> wrote:
> >
> > You made your own dish? Can you share construction details? How did you=
 design and make the mould? How thick did you make the dish?
> >
> > Peter Shute
> >
> >
> > --------------------------
> > Sent using BlackBerry
> >
> > ________________________________
> > From: <naturerecordists%40yahoog=
roups.com>
> > To: <naturerecordists%40yahoogro=
ups.com>
> > Sent: Thu Jun 16 21:45:30 2011
> > Subject: Re: [Nature Recordists] parabolic mics
> >
> >
> >
> > Hello,
> > I hope this will help
> > http://soundcloud.com/freitojos/ms-stereo-the-first-3-5
> >
> > I put ms mkh 30/40 in a fiber glass 65cm parabola that I made and the f=
ocus of the parabola was the line in the limit of the parabola not inside t=
he parabola, in the limit.
> > Best regards,
> > Jos=C3=83=C2=A9
> > --- In <naturerecordists%40yahoo=
groups.com><naturerecordists%40yahoogroups.com>, "diesel33dsl" <dies=
elmil@> wrote:
> > >
> > > Thanks all dudes!
> > >
> > > Most of your answers can be synthesized with a 'try it and see' basis=
.
> > > Thats what I'll be doing then, once I have gear and mikes enough to m=
ake comparisons (and software and measurement tools too, we could give some=
 words here also about what tools you use).
> > >
> > > It is a pleasure to read your debates and opinions, specially now I a=
m starting to take it seriously.
> > >
> > > About using parabolas, i guess my decision is to gather some coins an=
d try to ask one of those swedish to send me a telinga set :)
> > >
> > > Positioning a shotgun mic in a parabola seems quite an unexpected go =
since I'd be combining two different caption ideas (thanks David B.) and pr=
obably locating the capsule in the focus is not easy due to mike size and s=
o on... I guess the same happens when trying to locate there two isolated m=
ics for a stereo take of a distant element.
> > >
> > > Thanks Raimund also, your Goshawk take makes worth the try with my ap=
proach.
> > >
> > > What's clear is that small/light mikes will fit best there and omnis =
pointing to reflected sound are best choice...
> > > i guess the Telinga sets include good mikes on them, specially design=
ed for better performance, but has anyone of you got better results by swap=
ping default Telinga mikes with others?
> > > Or, is my choice to get a Telinga set (dish, handle, mount) without m=
ikes and put some specific models there?
> > > Which models/brands go well here?
> > >
> > > Thanks!
> > >
> > > --- In <naturerecordists%40yah=
oogroups.com><naturerecordists%40yahoogroups.com>, "Avocet" <brini@>=
 wrote:
> > > >
> > > > > Question 2:
> > > > Is the parabola approach designed to be used with JUST omni mics?
> > > > Are other caption patterns allowed, or is it senseless to use
> > > > directional mics here?
> > > >
> > > > Dani,
> > > >
> > > > As a supplementary answer, try any mic with a parabola and see what=
 it
> > > > does. However, bear in mind that a double mic or a gunmic will be
> > > > wider or longer than the high frequency focus of the parabola so th=
e
> > > > basic parabola theory won't apply.
> > > >
> > > > > Does this enhance directivity for a shotgun?
> > > >
> > > > You would be combining two very different directional principles an=
d
> > > > it is unlikely that they would reinforce each other's characteristi=
cs
> > > > but try it. And it is likely that they would reinforce each other's
> > > > disadvantages.
> > > >
> > > > BTW I regard the MKH 416 one of the most useful mics available and
> > > > can't see how it can be improved on except for the MKH 816 (still
> > > > available second hand). If you have a bottomless pocket there is th=
e
> > > > MKH 8070 which has an amazing spec but I can't afford two of them f=
or
> > > > stereo. :-) I think the law of diminishing returns would act here,
> > > > money-wise.
> > > >
> > > > Going to basic parabola theory:
> > > >
> > > > a) The focus is finer at higher frequencies and virtually non-exist=
ant
> > > > at low freqencies.
> > > >
> > > > b) An omni mic will pick up both direct sound and reflected sound a=
nd
> > > > at some frequenies these will tend to cancel out, but for most want=
ed
> > > > frequencies the reflected sound swamps the direct.
> > > >
> > > > c) A cardioid theoretically avoids cancellation effect type b) but
> > > > other diffraction effects still apply. A cardioid is always more
> > > > susceptible to wind and handling noise. Take your pick on
> > > > disadvantages.
> > > >
> > > > d) Stereo with a parabola is only possible using two points just
> > > > off-focus on either side. The theory behind this is complex so tria=
l
> > > > and error is the best method of finding out what works.
> > > >
> > > > David
> > > >
> > > > David Brinicombe
> > > > North Devon, UK
> > > > Cogito cogito ergo cogito sum - Ambrose Bierce
> > > >
> > >
> >
> >
> >
> >
> >
> >
>
>
>
>
>
>








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