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6. Re: parabolic mics

 Subject: 6. Re: parabolic mics "Peter Shute" pshute2 Thu Jun 16, 2011 9:49 am ((PDT))
 ```Thanks for that. What diameter and focal length did you use?=0D =0D Apologies for hijacking this thread.=0D =0D Peter Shute=0D =0D =0D --------------------------=0D Sent using BlackBerry=0D =0D ________________________________=0D From: m("yahoogroups.com","naturerecordists");=0D To: m("yahoogroups.com","naturerecordists");=0D Sent: Thu Jun 16 22:48:03 2011=0D Subject: Re: [Nature Recordists] parabolic mics=0D =0D =0D =0D Hello,=0D I have used this exel=0D http://graffiti.virgin.net/ljmayes.mal/var/parabola.htm=0D =0D after computation you make your elements in hard papel, you connect the ele= ments toghether with tesa film you chose a place with sand and you put the = paper parabola sustained by the sand. After that you make with water and cl= ay a soup, you put the soup in the parabola for one day. With a knife and s= and paper you makes a good mold. After that you puts the fiber glass, two t= imes at least but you can make the parabola as thik as you like it.=0D Good job,=0D Best regards,=0D Jos=E9=0D =0D =0D --- In m("yahoogroups.com","naturerecordists");, Peter Shute wrote:=0D >=0D > You made your own dish? Can you share construction details? How did you d= esign and make the mould? How thick did you make the dish?=0D >=0D > Peter Shute=0D >=0D >=0D > --------------------------=0D > Sent using BlackBerry=0D >=0D > ________________________________=0D > From: m("yahoogroups.com","naturerecordists");=0D > To: m("yahoogroups.com","naturerecordists");=0D > Sent: Thu Jun 16 21:45:30 2011=0D > Subject: Re: [Nature Recordists] parabolic mics=0D >=0D >=0D >=0D > Hello,=0D > I hope this will help=0D > http://soundcloud.com/freitojos/ms-stereo-the-first-3-5=0D >=0D > I put ms mkh 30/40 in a fiber glass 65cm parabola that I made and the foc= us of the parabola was the line in the limit of the parabola not inside the= parabola, in the limit.=0D > Best regards,=0D > Jos=C3=A9=0D > --- In m("yahoogroups.com","naturerecordists");, "diesel33dsl" wrote:=0D > >=0D > > Thanks all dudes!=0D > >=0D > > Most of your answers can be synthesized with a 'try it and see' basis.= =0D > > Thats what I'll be doing then, once I have gear and mikes enough to mak= e comparisons (and software and measurement tools too, we could give some w= ords here also about what tools you use).=0D > >=0D > > It is a pleasure to read your debates and opinions, specially now I am = starting to take it seriously.=0D > >=0D > > About using parabolas, i guess my decision is to gather some coins and = try to ask one of those swedish to send me a telinga set :)=0D > >=0D > > Positioning a shotgun mic in a parabola seems quite an unexpected go si= nce I'd be combining two different caption ideas (thanks David B.) and prob= ably locating the capsule in the focus is not easy due to mike size and so = on... I guess the same happens when trying to locate there two isolated mic= s for a stereo take of a distant element.=0D > >=0D > > Thanks Raimund also, your Goshawk take makes worth the try with my appr= oach.=0D > >=0D > > What's clear is that small/light mikes will fit best there and omnis po= inting to reflected sound are best choice...=0D > > i guess the Telinga sets include good mikes on them, specially designed= for better performance, but has anyone of you got better results by swappi= ng default Telinga mikes with others?=0D > > Or, is my choice to get a Telinga set (dish, handle, mount) without mik= es and put some specific models there?=0D > > Which models/brands go well here?=0D > >=0D > > Thanks!=0D > >=0D > > --- In m("yahoogroups.com","naturerecordists");, "Avocet" w= rote:=0D > > >=0D > > > > Question 2:=0D > > > Is the parabola approach designed to be used with JUST omni mics?=0D > > > Are other caption patterns allowed, or is it senseless to use=0D > > > directional mics here?=0D > > >=0D > > > Dani,=0D > > >=0D > > > As a supplementary answer, try any mic with a parabola and see what i= t=0D > > > does. However, bear in mind that a double mic or a gunmic will be=0D > > > wider or longer than the high frequency focus of the parabola so the= =0D > > > basic parabola theory won't apply.=0D > > >=0D > > > > Does this enhance directivity for a shotgun?=0D > > >=0D > > > You would be combining two very different directional principles and= =0D > > > it is unlikely that they would reinforce each other's characteristics= =0D > > > but try it. And it is likely that they would reinforce each other's= =0D > > > disadvantages.=0D > > >=0D > > > BTW I regard the MKH 416 one of the most useful mics available and=0D > > > can't see how it can be improved on except for the MKH 816 (still=0D > > > available second hand). If you have a bottomless pocket there is the= =0D > > > MKH 8070 which has an amazing spec but I can't afford two of them for= =0D > > > stereo. :-) I think the law of diminishing returns would act here,=0D > > > money-wise.=0D > > >=0D > > > Going to basic parabola theory:=0D > > >=0D > > > a) The focus is finer at higher frequencies and virtually non-existan= t=0D > > > at low freqencies.=0D > > >=0D > > > b) An omni mic will pick up both direct sound and reflected sound and= =0D > > > at some frequenies these will tend to cancel out, but for most wanted= =0D > > > frequencies the reflected sound swamps the direct.=0D > > >=0D > > > c) A cardioid theoretically avoids cancellation effect type b) but=0D > > > other diffraction effects still apply. A cardioid is always more=0D > > > susceptible to wind and handling noise. Take your pick on=0D > > > disadvantages.=0D > > >=0D > > > d) Stereo with a parabola is only possible using two points just=0D > > > off-focus on either side. The theory behind this is complex so trial= =0D > > > and error is the best method of finding out what works.=0D > > >=0D > > > David=0D > > >=0D > > > David Brinicombe=0D > > > North Devon, UK=0D > > > Cogito cogito ergo cogito sum - Ambrose Bierce=0D > > >=0D > >=0D >=0D >=0D >=0D >=0D >=0D >=0D =0D =0D =0D ```
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