if you take apart a 416 (or any of the sennheiser shotguns) what they reall=
y have are not slots so much as circular holes. my ancient 805, which is th=
eir longest, has holes every inch or so, and they are grouped into four or =
five sizes. the smallest holes are near the capsule, and the largest near t=
he opening. the holes are then covered with a fine fabric, the whole pipe i=
s covered with a stainless mesh and a second tube slides over the whole. it=
is this tube that has the slots. There are very small shotgun designs whic=
h only have circular holes, and no slots.
you do need a cardioid capsule ( i built the popular mechanics design, ye=
ars ago, with omnis a few decades ago.)
umashankar
Rich Peet <> wrote:
--- In "Rich Peet" wrote:
>
> I will try and build an interference tube for my wl183 this week and
> post an example to show if it works or not.
Ok, so what happens when you take a copper tube and just screw the
math and start cutting slots into it to build a interference tube
shotgun mic?
http://home.comcast.net/~richpeet/wl183-shotgun.jpg
I ran out of fine sawblades as these break about every 6" I cut.
But I came close to completion.
Ran it through the cooledit/audition to test the results.
This was not a controlled test and was just done in my work area at 10
feet from the speaker.
The mic "on" target with the tube showed a 10 db cut from 3 to 5.5
thousand cycles compared to the matched one mounted above. It
performed about the same in the rest of the spectrum.
"Off" axis the mic off target with the tube showed a 20 db cut from 3
to 5.5 thousand cycles comapred to the matched one mounted above. It
performed about the same in the rest of the spectrum.
Translated this means it will continue to be something fun to play
with but Walt is right in that it will take better quality mics to
play in shotguns.
Rich Peet
"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
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