t's From:
>
> Good questions, which I for one will be following along with as I try
to rig something for my current mics. Is there a lower limit for the ID
of the zeppelin compared to the OD of the mic element? Would someone
care to recap briefly the reason for the choice of fake fur? Is it
particularly acoustically transparent? I mean, why not cotton or
tarlatan? My mics have low cut switches, designed primarily for
proximity effect, but could the known curve of that contribute to screen
design? BTW, I don't know modern mics very well, how common are low
cuts? Or have designers found other solutions for proximity effect?
(which wind noise almost seems to be a variety of, it strikes me).
The minimum diameter zeppelin I've seen is 3" in diameter, a pretty old
one I have a MKH-416 in right now. There were probably some even
smaller. Most modern mono zeppelin's are about 3.5". If you get too
small the wind will not smooth out before reaching the mic. As has been
noted, the larger the better. The size used is a compromise.
For stereo the traditional M/S zeppelin is either 5" or 6", you can see
one of those holding my M/S MKH-80 pair. I've worked out that, with the
design of the Sennheiser suspension, I can fit a M/S into a standard
mono zeppelin with little compromise in wind protection. I use that in
my M/S MKH-40/30 and MKH-60/30.
The outer layer of your wind protection has to have the property that it
does not produce wind turbulence. Many materials will produce turbulence
on a micro scale, and that produces noise. Fake fur gets around it by
being highly irregular and damping out the turbulence. There is a fairly
wide variation in the acoustic transparency of the fur. I generally
choose fake fur that has long, irregular length fur that's not too
stiff, no filler in the backing and a thin knit backing. I have had a
expert in fake fur (a teddy bear manufacturer) take a look at rycote's
fake fur and he said it was a standard type, nothing special.
Note some try to take a different approach than the fur for the outer
cover. They typically will use panty hose, or a equivalent in thin
lycra. The idea is that it's supposed to be smooth enough to not cause
turbulence. While effective, it appears to me to be less effective than
the fur.
In rycote's modular system, in addition to the fur cover there is also a
fleece like cover available. It's not as effective as the fur, but is
used by some. It's even possible, though tough to assemble, to use both.
To my mind the practice of filtering out the low end to lower wind noise
in a recording is wrong. First off wind noise is not just there, but
more important that low end is part of the natural ambiance and removal
takes a lot of character away from the recording.
In terms of making zeppelins, the early zeppelins were made from a
textile mesh, very similar to the mesh used for craft hook latch rug
making. Later they went to a all plastic molded mesh that's pattered
like the original. The original material material was molded to shape,
probably when wet, and then painted. The paint locked in the shape. I
have a old zeppelin made exactly that way, you can see the original mesh
in spots on the end where the paint has worn away. This method is
probably easier than trying to thermally mold the plastic canvas
material to a shape like the end domes on a zeppelin. I've experimented
with molding plastic canvas and it takes a temperature just a little
above the boiling point and a two part mold to force the material to
shape. I've a piece of the latch hook material, but have not yet gotten
around to doing some molding with it. I want to build a xy stereo setup
with my pair of MKH-816's and no commercial zeppelin system will fit a
xy stereo of that size.
What's more, with the paint method, you could press the fill material
into the mesh while the paint was still wet to get it glued on. A
commercial zeppelin is a windscreen in it's own right, not just large
mesh to support stuff. The fill fabric is a essential part to making the
zeppelin a screening layer. Using just open mesh and covering it with a
layer of fur is only one layer. The commercial setup has 2 or three
layers of protection by the time the fur is on. Rycote lines their fur
cover with a layer of nylon taffeta, making the third layer. They have
not always done this, and some fur covers are just the fur fabric alone.
With the zeppelin that's two layers instead of three.
Note with a commercial setup the suspension is part of the framework of
the wind protection. The zeppelin slips onto the track of the suspension
and is locked to it in a rattle free arrangement. It's important that
the frame of your wind protection does not rattle or creak. This also
makes it very easy to slip the system apart to remove or adjust a mic.
That aspect is one of the hard parts to duplicate, though I could do so
by milling the track and slot on a homemade. It was the amount of work
involved in doing a suspension and zeppelin as a integrated unit like
this which was why I did not build my own.
As far as a particular incoming wind direction, that's more a academic
than practical question. Wind in most situations is not a nice laminar
flow from one direction, but eddies and swirls. You have to protect from
all directions. In this regard, getting the mic higher will get into
smoother air currents. Even my 17' high mic setup is enough to notice a
lot of smoothing in the wind. This is the reverse of the general advice
of hiding behind something. I wind protect well, then stick it up in the
wind. Up where it's a little less turbulent.
Walt
________________________________________________________________________
________________________________________________________________________
|