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Re: surround recording

Subject: Re: surround recording
From: Dan Dugan <>
Date: Tue, 29 Jun 2004 14:51:51 -0700
ROB DANIELSON
>  >used the DBX compander system for reel to reel
>>   >for years and it was not kind to low signal
>  >>levels.

DAN DUGAN:
>  >Maybe it was out-of-range on the quiet stuff? I don't recall a
>>problem with that in my dbx years.
>
>Correct, the quiet passages would drop beneath the threshold. I fear
>low levelss/quiet locations will cause the compander circuit to
>create extra noise if not pumping. I hope not though, I'd love to not
>drag wires.

I just threw that idea out because my automatic mixer can "fall off
the bottom" of its compander-like function at low input levels, but
I've never experienced it with dbx. Sounds like either a defective
unit or not level-matched properly. I'd try the companded wireless
links before buying, though, you can't expect people designing those
to be thinking about the very low levels we nature recordists love.

>  >
>>>(I start both packs running
>>>between the wide mics, sync them all and carry
>>>them out.
>>
>>So you use separate recorders for the wide rear left and right?
>
>Not usually, though its possible. I often put the wide spread
>cardioids on FL and FR to create the horizon  because these channels
>have subwoofers on them. The M-S pairs might go LF/RF with LR/RR or
>LR/LF with RR/FR and even LR/C and RR/C  or RR/LF with LR/RF. I try
>to find the "scale" that a set of files seems to want to present.
>Sometimes I get lucky and guess at the right scale in the field, but
>not often. Its alchemy at this stage of learning.

I agree it's an artistic choice how to distribute the channels you
get. I'm totally confused by your channel abbreviations.

>  >
>>>MD's are astonishingly speed accurate)
>>
>>You're either lucky or not noticing. Do you do a tail synch to check
>>for drift? The two Sharps that Sharon and I use drift a few inches
>>apart per minute. With the wide-spaced rears it won't matter much,
>>anyway.
>
>Lucky I guess. Yes, I try to tail slate.  For a class project, we ran
>4 (MT-90) MD's for 70+ mins and found the drift between them was on
>the order of one second.

In sound travel time, that's 1,150 feet at normal temperature, or 16
feet per minute, not good synch at all.

>I corrected it by changing the sample rates
>and it was almost too small for Logic to calculate.  I do slide
>tracks when the timing difference from a spread isn't complimenting
>something.   I think when one works in an enclosed space where the
>sound from all directions is roughly balanced in volume by
>reflections from the architecture, symmetrical arrays can capture
>this. Maybe outdoors, especially in open areas, its more critical to
>get each mic in a place with an interesting sound perspective and
>then find a complimentary scheme for overlapping the perspectives in
>post. Of course, in very quiet spots, the "spheres" of the mics
>overlap more and the mics can be placed further apart.  The timing
>differences can be yucky at times. and blissful at others.

That's been my experience, too. I've been spacing two stereo arrays
15-40 feet apart, and with the closer arrays it can sound like a room
(where you want it to sound like outdoors).

>My
>preference is to record for hours, let nature choreograph and pick
>the stuff that works.   Rob D.

Since my main stereo mics are body-mounted, I usually do 2-10 min
takes, though my longest was 40 minutes. One does get stiff holding
still that long.

-Dan Dugan


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