Recording - November 2014 - 16

should be aware that whenever you do this, you introduce phase shifts, and it's in
that design that the tonal quality of any directional microphone lies.
So the magic is in how you design the
way that sound gets to the back of the
microphone, as opposed to how it gets
to the front?
Exactly. Let me tell you just a short story
here. Developing the 4011 capsule, which
we still consider one of the best cardioid
microphones in the world due to its
extreme off-axis linearity, actually took
around ten years before the Danish developers were satisfied at that time. It goes
back some 25 years now and it's still
among the best; we actually could not
have made it any better today. If you study
that microphone, you will see that it's not
only linear on axis, but we wanted it to
have the same linear response at all angles
out to 90 degrees... just attenuated. For the
4011 we made the capsule have that
polar pattern at all frequencies, from down
to 30 Hz up to at least 12 kHz, above
which the diaphragm diameter starts to
introduce high-frequency "shadowing."

Now that implies, for our
readers who are just learning this stuff, that most
cardioid microphones do
not have the same polar
pattern if you go to lower
or higher frequencies.
We are often met with,
"It's a cardioid, so I'm safe, because then
I reject the angles I do not want to capture." And we have to ask back, "At
which frequency range is it actually a cardioid?" Anybody can draw the heart
shape of a cardioid mic on a polar pattern, but the thing is, that might be the
directional shape at some frequencies,
normally in the midrange, at 500 Hz to 4
kHz for instance... but in most other frequency areas they are close to omnis!
I think that is something important to
give your readers. A microphone is a
sound shaping device, and the way that
it behaves to its surroundings cannot be
changed afterwards! You can EQ, but
you EQ on 360 degrees around the mic.
You can't change the way it internally
blends the soundfield capture.
Are there certain polar patterns that are
going to give you more sound coloration
than others? Can you sort of get a feel
for what a microphone's tonality might
be, based on its polar pattern?

As soon as you introduce the pressure gradient principle, you will also always suffer
from the proximity effect. You just have to be
aware that it's there. Going very close to
instruments, as we do with many of our products, we often choose an omni microphone
solution, because we can go extremely
close-and even inside the instrument-without being punished with too much bass.
The idea being that as you grow closer
to your sound source with a directional mic, the low frequencies are accentuated with respect to the mids and
the highs?
And the other way around. If you move
further away, you will experience a bass
frequency drop.
Are certain diaphragm sizes better
suited to certain polar patterns?
As I said that not all cardioids are cardioids, omnis are also only omnis up to a
certain frequency. From that certain frequency, they will also start to be directional to some extent, and that is in direct correlation with the diaphragm size. The bigger the diaphragm diameter, the sooner
the omni microphone will start behaving
like a cardioid. A very small diaphragm
stays omni at higher frequencies; that's
why we see that measurement mics always
have small diaphragms.

Recording - November 2014

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