If the mic is recessed in the boundary and theres a cavity formed due to th=
e mic body and capsule postion then the boundary will be affected, a resona=
tor is formed which will narrow the directivity and also boost the high fre=
quency response at the same time for direct sources, for side on its probab=
ly attenuating more than an exposed / flush mounted capsule.
If the mic body is sticking though the boundary then you may attenuate the =
boundary effect at high frequencies (> 10Khz) cause narrowing of the pickup=
pattern, and possible secondary reflections depending on how far away the =
diaphragm is. -Sound wave arrives at the boundary, traverses along the boun=
dary hits the outer edge of the mic body and diffracts, some waves continue=
over the obstruction and contribute to the boundary. Size of the cylinder,=
depth to the capsule are parameters that can be modeled but beyond this di=
scussion. Its one reason measurement mics have a slotted head to improve of=
f axis response.
All of the above depends on the mic diameter and how far it is away from th=
e boundary surface, for most material < 8khz your fine.
Play with the (use google) "ripple tank" application to see such effects in=
the browser, but for most the actual influence is very small and may even =
be beneficial narrowing the polar response.
All hot air without testing the effect of the MKH flush mounted and then po=
king out to the diaphragm depth.
BR
-Mike.
--- In vickipowys <> wrote:
>
> Hi Dan,
>
> Thanks for your comment!
>
> A question, wouldn't the metal tube of the mic then block some of the =
> sound that had been gathered by the boundary surface, from reaching
> the mic element?
>
> I am not quite sure how to visualize how the sound gathering works. =
> Any explanations? Anyone?
>
>
> Vicki
>
>
>
>
>
> On 22/11/2011, at 2:01 AM, Dan Dugan wrote:
>
> >> http://www.caperteebirder.com/index.php?p=3D1_27_recording-gear-2
> >
> > On that page you say:
> >
> >> MKH 8020 not suitable for SASS:
> >> One drawback to the 8020s is that the mic element is set 5-10 mm
> >> inside the mic housing, rather than flush with the surface, making =
> >> the mic unsuitable for SASS-style of mounting. (For SASS the mic
> >> element needs to be flush with the boundary surface).
> >
> > This is not a problem! Let the mic stick out from the surface of
> > the baffle (SASS or whatever kind of baffle you want the mic to be
> > flush-mounted in) so that the diaphragm of the capsule inside the
> > housing is level with the baffle surface.
> >
> > -Dan
> >
>
|