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Re: Decca Tree?

Subject: Re: Decca Tree?
From: "Kevin Colver" kjcolver
Date: Thu Aug 28, 2008 9:25 am ((PDT))
> Scott,
>


Thanks for the Decca info.  Regarding the placement of mics up and
over the sound field, I've wondered about this in field recording.
Sometimes, when on a steep hill, I get this effect and it gives a
nice stereo field.  Walt mounts his mics on a very tall mic stand
with good results.  Does the group think this would be worthwhile to
try to consistently achieve?  Usually if my mics are nearly at ground
level I get a dull and blunted stereo effect.  I've wondered if I
should string my MKH 30/40 pair up on a rope into a tall tree to get
this effect?  Does anyone do that?
Kevin


>
> testing using spaces instead of tabs. the last ascii diagram got
> mangled
> hope this one works better>>
>
> Still mangled. Let me try an alternative Decca description: Stretch
> both arms straight out to your left & right. Grab an omni mic in each
> hand & aim outward at a 30 to 60 degree angle. Now imagine a center
> mic mounted anywhere from mid-arm to full arm's length directly out
> in front of your neck. That's a basic Decca arrangement & it is
> placed close to & over the orchestra, with the mics aimed down. The
> set up can scale larger or smaller depending on the size of the
> soundstage it is intended to pick up. The arm's length model would
> work well for the average chamber ensemble, a somewhat larger size
> works for a symphonic orchestra, & smaller is appropriate for a
> string quartet. As for ambient field recording, I personally don't
> see the application working very well. The Decca stereo field is a
> result of arrival time & amplitude differences between the 3 capsules
> & is governed largely by the proximity of each element in the stereo
> field to any given mic in the array. In other words, the first
> violins are clearly heard primarily left because they may be as much
> as 50% closer to the left mic than the others. On the other hand, a
> bird 50 feet or more horizontally in the distance will basically be
> picked up equally well by all three mics, because it is not within
> the general depth of field perceived by the offset arrangement &
> overhead placement of the Decca tree. If you can get up & over an
> active sound environment with a Decca arrangement, it will result in
> a deep, three dimensional sound field. Otherwise, at a distance, a
> standard XY, MS, ORTF or AB stereo approach will provide a more
> coherent stereo image.
>
> Scott Fraser
>
>
>
>







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