[Top] [All Lists]

Re: Making a parabola

Subject: Re: Making a parabola
From: "freitojos" freitojos
Date: Fri Sep 21, 2012 7:28 am ((PDT))
Once more thank you for your knowdlge and tips, they are precious.
About your previous ( in another post) coment and answer about the stereo s=
ound in a parabola, as you have said it is questionable but here are two fi=
les with mkh 30/40 in a 60cm fiberglass parabola 15cm focal lenght, once yo=
u have said, and it was right of corse, that the side gain was too low mayb=
e it was the case here I d'ont remember, now I balance the gain in the two =
channels better.
In my cans and in my speakers I think it is stereo.
My next experiment would be to put the mkh30/40 in my fiberglass 40 cm para=
bola and compare the results with those in the 60 cm parabola.

--- In  "Avocet" <> wrote:
> > This formula is a general formula for waves, light, radio or sound
> > in a parabola,
> Jos=E9,
> This is exactly the problem. Sound waves are fundamentally different
> from light and radio waves. Firstly, they are longitudinal not lateral
> waves and secondly, their wavelength is comparable to the dimensions
> of the parabola. Thirdly we are using them over a 20:1 range of
> frequencies, not a narrow band like light or radio waves. The good
> news is that the coefficient of reflection of sound with a solid
> surface is near 100%.
> The bad news is that you won't get a clear focussed image from the
> dish. The best you can hope for is the sound equivalent of a fuzzy
> blob where most of the focussed energy will completely miss the mic.
> That's the simplest explanation for the loss of low frequencies where
> the blob gets larger. You can plot the focus pattern by moving around
> a small mic.
> A parabolic mic does its job well, which is bringing in kilohertz
> frequencies where it it more directional than any other type of mic.
> Just don't expect a good music balance from one. :-)
> A general rule with location sound recording is to use what works in
> practice. In the end our ears are the best judge rather than the
> theory.
> David
> David Brinicombe
> North Devon, UK
> Cogito cogito ergo cogito sum - Ambrose Bierce

<Prev in Thread] Current Thread [Next in Thread>

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the naturerecordists mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU