On 12/29/2012 02:54 PM, Fons Adriaensen wrote:
A directional mic can give quite a bit more than just
a few dB of added
headroom before feedback. Take a look at the
frequency response charts of
the 'standard', the SM58, which pretty much has 10dB down across the
board.
True if you consider only the direct sound, which may be valid
in the case of monitors close to the mic. OTOH, if the feedback
is mainly due to indirect sound which will come from all directions
then a cardioid provides just 4.8 dB advantage. Which of course
could make a difference.
Possibly true, but consider the fact that a floor wedge is the loudest
source reproducing the mic signal. The monitor (or monitors) will
typically be at 110-120dBa, and aimed directly at the back of the
microphone. You can easily use the polar response of the microphone to
reduce feedback. For example, an SM58 has the best rejection at about
160 degrees off axis. A hyper-cardiod, such as a Beyer M88 has the best
rejection about somewhere around 120 degrees off axis.
An omni-directional mic is unusable is any situation where that mic is
being fed into a monitor system, unless the source is at least 20dB
louder than the monitor signal, which MAY be the case if you're micing a
guitar cabinet, since a) the cabinet would be close-miced, and b) there
probably isn't a monitor aimed directly at the front of the guitar cabinet.
It would NOT be suitable at all for vocals, or when you're micing horns,
acoustic guitar, violin, etc.
It would also be complicated if you are using side-fills, as is
typical. Of course, it's also complicated by stupid things such as
whether or not the lead singer decides to put on a hat!
I mixed monitors for many many years. It's far more complicated than it
would appear at a casual glance. You get 8-10 on-stage monitor mixes,
running a total of about 100,000 watts (including sidefills), and
there's a lot going on.
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