Dan Dugan wrote:
> It's normal for an interference-tube mike to be wide at lower
> frequencies and narrow down at high frequencies. Not desirable, but
> the nature of the beast. Any mike pattern narrower than hypercardioid
> suffers from severe frequency coloration off-axis.
It's really true anytime you have more than one path for the sound to
reach the diaphragm, as those paths are frequency dependent.
> The new DSP super-directional mike from Audio-Technica, the AT-895,
> claims super-directionality all the way down. They don't publish
> polar patterns, which is a clue they might be ugly.
And at something like 24dBA self noise it's pretty noisy for a quality
nature recording mic. I figure that concept needs a bunch more work for
us. At least at the price they want for it.
> Note that the scale of the polar pattern is in dB. This means that
> the shape of the pattern on the chart is not the same as the shape of
> the pattern in space. Sennheiser used to use a linear scale, from 0
> in the center to 1 at the periphery, but alas a few years ago they
> gave it up to do what everybody else was doing. A dB scaled polar
> plot looks fatter and wider than the actual pattern in space.
The link I gave gives a more generalized 3d view, that's probably a bit
more realistic of actual:
http://www.sennheiserusa.com/pdf/rfcm.pdf
Before we get too sweaty about pretty polar patterns it's well to
remember that the natural environment out there is busy modifying the
sound considerably on it's way to our mics. Combine those with the mic's
response pattern and it gets much more complex and uneven. Before
starting recording, I'll usually wander around a bit with mic in hand
listening to what I get, hunting the good spots to have the mic. You
cannot predict it just by looking at graphs and the site.
Walt
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