Posted by: "Rich Peet"
>
> --- In Scott Fraser
> <> wrote:
> Shotguns are
>> > designed primarily for voice pickup at relatively close distance & do =
>> > some audio 'damage' in order to obtain good off axis rejection.
>
> Sorry, I don't buy into the design being for close distance. Maybe
> just your schooling and perspective.
The design is for a directional boom mic. And it does depend on what you
call close. Boom mics are used very close compared to the range of
distances that nature recordists work. The design is not for a specific
distance, but it works best close.
The more important point as far as nature recording is that a shotgun
mic has no inherent gain. It cuts off the sound from off axis somewhat,
but the sound that's on axis will be no better signal than a omni or
cardioid with the same sensitivity. Shotguns work at distance only by
supplying the needed gain with a amplifier. And the amplifier provides
gain not only for the signal you want, but amplifies the self noise of
the mic by the same amount. The self noise of the shotgun quickly
becomes limiting as to how much gain, and thus distance, you can use.
When considering self noise of a mic you need to take into account the
amount of gain you will be supplying. For shotguns that will be a lot
for a distant subject, for parabolics (the other main choice for
distance) it will be a lot less. So the mic you use for a parabolic can
have higher self noise as it gets a lot of gain before the mic, and thus
gain without increasing the self noise. To come close a shotgun has to
have very high sensitivity and very low self noise relative to what one
is using in a parabolic.
> All directional mics suffer on off axis. And with this logic M/S
> don't work.
M/S is a different problem, as are all stereo setups, the combination of
two polar patterns used for a specific purpose. Mono mics are just one
pattern. Not the same thing as the stereo is reproducing a dimensional
field while the mono is only reproducing sound levels with no
dimensional field (or maybe one dimensional).
And M/S does work well.
Newer shotguns have better off axis patterns than the older ones, and
that cleaner pattern is a lot of the cost in higher priced shotguns.
Compare a MKH-416 to the MKH-60. Most inexpensive shotguns will be like
the MKH-416 or worse in polar patterns. Depends on how much variation in
off axis sensitivity you are willing to tolerate.
Walt
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