Rob Danielson, you wrote:
>A colleague asked me why the sennhesier MKH-70 chart shows such
>frequency asymmetry in it's pick-up pattern. Seems like this could
>create off-axis asymmetrical coloration. Anyone familiar with this?
>Here's the sennhesier chart to save the trouble of moving through
>their site frames:
>
>http://www.uwm.edu/SOA//Film/Danielson/MKH70PolarFreqResponse.jpg
The asymmetry between left and right sides of the chart is because
they are two different charts on the left and right sides. Different
frequencies are represented, a group of lower frequencies on the
left, and higher frequencies on the right side. See the legends in
the lower left and right of the illustration. At any given frequency,
the polar pattern will be symmetrical about the axis. That's why they
economize by showing only half of the pattern for each frequency.
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.
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.
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.
-Dan Dugan
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