Walt wrote:
>The realities of portable recording in natural environments pretty much
>force us back toward the purist approach.
>
>How would you apply the 3:1 rule to a bird calling 50 feet away? That
>seems like it's going to lead to darned large mic separations in
>multimic setups. Or deal with the elaborate phase shifting and
>reflections in a multimic situation?
"...to reduce phase cancellation...the miking distance should be less
than 1/3 the distance between mics." -Bruce Bartlett (Sound Advice)
Yes,.. 150 feet apart! As Rich described in an earlier report, we
set four omni mics along 240 feet of the Kickapoo River:
http://www.uwm.edu/PSOA///Film/Danielson/Surround/StarValleyArray.jpg
facing a tall limestone wall:
http://www.uwm.edu/PSOA///Film/Danielson/Surround/StarValleyReflector.jpg
and a famous binaural pair in a tree set back about 50':
http://www.uwm.edu/PSOA///Film/Danielson/Surround/StarValleyBlockhd.jpg
Part of the fun is finding field realities to collaborate with. We
fussed with trying to figure out how to arrange our "three stereo
pairs," but when I got home I suddenly realized,.. any two mics
create a stereo pair: 1+2, 1+3, 1+4, 1+5, 1+6, 2+3, 2+4, 2+5, 2+6,
3+4, 3+5, 3+6, 4+5, 4+6, 5+6 =3D 15 stereo pairs. In 5.1, I count 10
not counting virtual speakers.
So where's the dreaded phase cancellation? Out of curiosity this
afternoon I used a VST plug called "round panner" to place (mix) six
channels randomly within a 5.1 speaker arrangement. Over 15 minutes,
I heard a very minor phase dip or two and a couple of unnatural slap
back echoes. A sense of unified space was always maintained. Perhaps
phase cancellation depends on precise alignments and uniform
surfaces, which the landscape doesn't provide? The limestone wall
could be acting a little like the rim of an ear -- adding useful
complexity while reflecting. There is some parabolic focusing as
when a distant owl is picked up only on one mic and gurgling from the
river that is unexplainably up front. At times there is too much
going on for me, but its refreshing to be able place some mics a
further away from hot spots and use the air.
>
>And then there is the problem of practical, battery operated portable
>multichannel recorders.
sans the car battery and long runs of wire:
http://www.uwm.edu/PSOA///Film/Danielson/Surround/StarValleyTibookRec.jpg
> And that a simple mic becomes a elaborate
>balloon of suspension and wind protection.
>
>And how much we can carry before we collapse under our load. I really
>hate it if I have to make two trips through the brush to get the gear to
>where I'm recording. It's real restricting, we need to be as mobile as
>our subjects.
It started me thinking more about the Sound Devices 744,...two mic
preamps, 4 channels and fits in the palm of a hand. Add an MP-2,
battery pack and it would be much smaller than my current stereo rig.
While working with the files on the laptop, I discovered I was making
global EQ settings, regions, exporting sub files, logging and burning
to DVD-R all at the same time.
>
>And that most of us have no one paying the bills but us. Which limits
>what we can do.
>
>That's how we become purists. We just get too big a headache trying to
>get more elaborate stuff to work. Though as Bernie has pointed out in
>his book, mixing has it's place too.
The line between equalizing and mixing is one I'd like to cross less
often. Single field recordings standing on it their own-- Aaron Ximm
has great talent for this. When a recording seems to have promise, I
enjoy attenuating the dominant frequencies that are masking
attentions to other frequencies and textures. Each file brings a
complex of issues to resolve. When I have to mix files to create
something that is missing its a lot of work to do right and not as
much fun. Recording six channels at once using only what's there has
some of both methods.
>
>The equalization techniques of the studio still apply to my mind. The
>listeners are the same, and mostly listen with the same equipment that
>they listen to music. The actual techniques used will differ, and there
>certainly is no nice handy cookbook around. Comparing notes on how we do
>it is definitely helpful. I certainly look at studio techniques with a
>eye to how I might apply them to what I do.
One good trick you probably know of, but others may not: Gradually
increase the playback volume from "off" making note of the tones and
textures your ears first detect. If you push these back with careful
EQ attenuation, more space opens. Even cutting back dominant,
sustained notes in animal calls can make the overall recording more
tonally balanced and the call more informative.
>
>
>Walt
>
I really should get that stereo book. I am working the Field Mic
List. Soon, I'll be asking some folks to provide comments about their
favorite mics/techniques. Rob D.
>
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