[LAU] Pro Audio? OT rant.

Al Thompson althompson58 at gmail.com
Sun Dec 30 16:19:30 UTC 2012

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.

My bands, CD projects, music, news, and pictures:

My blog, with commentary on a variety of things, including audio,
mixing, equipment, etc, is at:
Staat heißt das kälteste aller kalten Ungeheuer.  Kalt lügt es auch;
und diese Lüge kriecht aus seinem Munde: 'Ich, der Staat, bin das Volk.'
                                                - [Friedrich Nietzsche]

More information about the Linux-audio-user mailing list