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hollywood_steve
 
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Default Decca tree size - related to room size?

Is there anything resembling a formula or basic guidelines for sizing
a Decca tree? I know the proportions (2X from left to right, 1.5X
from front to back) as described in the New Stereo Soundbook: but can
the overall scale be related to the size of the facility somehow?
What guidelines would someone use when designing a tree assembly? Is
there a smallest practical size or could I rig up 3 Schoeps mini mics
into a palm-sized tree? Seriously, what are the tradeoffs for smaller
vs larger and could the size be somehow related to how live/dead the
room is, or ???

steve

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Scott Dorsey
 
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Default Decca tree size - related to room size?

hollywood_steve wrote:
Is there anything resembling a formula or basic guidelines for sizing
a Decca tree? I know the proportions (2X from left to right, 1.5X
from front to back) as described in the New Stereo Soundbook: but can
the overall scale be related to the size of the facility somehow?


Not really. It relates to the size of the stereo image you want, and
the directionality of the microphones. The standard proportions are
about right for M50s.

What guidelines would someone use when designing a tree assembly? Is
there a smallest practical size or could I rig up 3 Schoeps mini mics
into a palm-sized tree?


I don't think you can do Decca miking with something as omnidirectional
as the Schoeps. The whole point of the system is that it takes advantage
of the top end directionality of a large diaphragm omni.

Seriously, what are the tradeoffs for smaller
vs larger and could the size be somehow related to how live/dead the
room is, or ???


The more you pull them apart and toe them out, the more separation you
get and the wider the image there is. If everything is clustered in the
center, pull them apart. If there's a hole in the middle, move them together.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Benjamin Maas
 
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Default Decca tree size - related to room size?

"Scott Dorsey" wrote in message
...

I don't think you can do Decca miking with something as omnidirectional
as the Schoeps. The whole point of the system is that it takes advantage
of the top end directionality of a large diaphragm omni.


I agree with this assessment to a point. I've used B&K 4006s in a decca
tree and wasn't thrilled with the result. I've used Schoeps but with the
MK21 capsules and had pretty good luck there. I like them as they tend to
approximate the response of an M50...

While I haven't personally tried it, there are also folks that will drill
out balls to put on the outside of the capsule and get good results that
way...

--Ben

--
Benjamin Maas
Fifth Circle Audio
Los Angeles, CA
http://www.fifthcircle.com


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ScotFraser
 
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Default Decca tree size - related to room size?

Is there anything resembling a formula or basic guidelines for sizing
a Decca tree? I know the proportions (2X from left to right, 1.5X
from front to back) as described in the New Stereo Soundbook: but can
the overall scale be related to the size of the facility somehow?


The Decca tree was designed for orchestras. You can scale it down when working
with smaller ensembles. Some of the best imaging I've ever heard on Kronos was
a smaller Decca tree arrangement set up for a film scoring date they did at
Todd-AO. Direct to room ratio was incredible. I'm sure there's a point where
downscaling the tree makes it stop working & the imaging falls apart, & I
suspect that point will be determined by the pattern of the mics you use.

The standard proportions are
about right for M50s.

Bobby Fernandez, an ace Hollywood orchestral sound track engineer, told me he's
converted from M50s to Sennheiser MKH20s. Says he gets the same overall sound,
but with a lot less self-noise.

I don't think you can do Decca miking with something as omnidirectional
as the Schoeps. The whole point of the system is that it takes advantage
of the top end directionality of a large diaphragm omni.

It may be a stretch to even use the term "Decca tree" in this context, but I
heard a system using Coles 4038s in a tree arrangement for the PBS "Sessions"
series. Sounded very good, but was really a bit more like 3 spot mics over the
band than a coherent stereo image. Might have worked better if they were pulled
in together more, but this is a preset flown overhead arrangement, a sort of
one size fits all thing for that show.




Scott Fraser
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Scott Dorsey
 
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Default Decca tree size - related to room size?

David Satz wrote:
Scott Dorsey wrote:

I don't think you can do Decca miking with something as omnidirectional
as the Schoeps. The whole point of the system is that it takes advantage
of the top end directionality of a large diaphragm omni.


The Neumann M 50 and its successors aren't large-diaphragm--they're small-
diaphragm pressure microphones with the transducer embedded in the surface
of a Lucite sphere. The sphere makes the response above a few kHz more
strongly directional, and bumps up the on-axis response slightly.


Okay, I'd call the M50 a large diaphragm, in that it's large enough for
off-axis response effects to exist, but that's just me. I'd say the same
for the 1" B&K as well. But yes, it's true that the sphere is where most
of the beaminess comes from.

What that description doesn't convey is the greatly increased focusing
ability of the microphones at a distance from the sound source. This
amazed me when I worked with M 50s at RCA Studios (they were a favorite
of our late head producer, Mr. Jack Pfeiffer). I recorded a CD of the
Tokyo String Quartet with M 50s under his supervision--the microphones
were over twice as far from the quartet as I would ever have placed any
pair of normal omnis, yet the sound is highly detailed without being the
least bit screechy.


Yes, this is true. You can also use the same mikes, incidentally,
in a baffled configuration and get a lot of that.

To mimic this setup with conventional pressure (omnidirectional) capsules,
both Schoeps and Neumann sell accessory spheres that can be slipped over
the ends of their respective small microphones. Schoeps even offers two
different sizes of sphere, each with a slightly different effect. Details
can be seen on http://www.schoeps.de/E/ka40-50.html which also gives a set
of frequency response graphs that show that aspect of the spheres' effect.
Neumann's Web site shows the polar response graphs of their current models
"M 150 Tube" and TLM 50, both of which use this type of construction; see
http://www.neumann.com/infopool/mics...?ProdID=tlm50s and click
on the tiny word "Diagrams" near the top of the page.


B&K also sells them, and I have never been able to get anything even
approaching the general sound of the M50 with them. It does increase
the high frequency directionality and I like using them that way with
baffled miking configurations, but I never could make them (or at least
the B&Ks) work in a Decca tree anything like the M50.

I've recorded only a little with Schoeps KA 40 spheres on MK 2S capsules.
It was a useful and pleasant experience; the effect of the spheres was
definitely quite noticeable. I mostly work with directional microphones
but if I were to use omnis again, I think that I would use the spheres
on them. The ability to back the microphones away from the sound source
and still maintain good focus helps to solve one of the real problems of
spaced-omni recording, which is the undue extra clarity given to sound
sources that are at the front of the ensemble as opposed to those which
are located farther back. There should be a difference--but when omnis
(or any other pattern of microphone to some extent, but omnis especially)
are close to the front edge of the ensemble, the players in back may be
literally ten times as far from the microphones as the players in front.
Reducing that from 10:1 to, say, 3:1 is a real improvement to my ears.


I agree, and I like the spheres a lot in general, but I still can't make
them work with a Decca tree and I haven't seen anyone else do it to my
satisfaction either. There's a local fellow here who uses MKH-20s with
the balls and it just doesn't sound like what I hear in the hall at all.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."


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