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Re: level setting

Subject: Re: level setting
From: Jeremiah Moore <>
Date: Thu, 7 Apr 2005 12:03:34 -0700
>I guess I was not clear enough in what I need.
>I have moved from multichannel laptop recording using de-correlated
>wide spaced microphone arrays to coherent full immersion surround
>recording.
>
>The results are wonderful and very direction accurate in a full 360
>degree field. But when I setup I need to define reference levels for
>each channel that I can see for use in post production.  This is
>needed to keep the immersion direction accurate.
>
>I can not point the mic at the sky, can not use a small radio as the
>volume changes as it is turned, and can not carry studio equipment
>into the field. I already carry 25 lbs into the field for a 3 hour
>record capability at 24/96 or 10 lbs for 16 bit atrac full day
>capability. Right now I am just setting levels based on a hold of the
>minimum valley gain and maybe that is good enough with a good quantity
>of material
>
>I am starting to think that accurate level settings are not done in
>the music industry except by ear.

Since the intended result is purely aesthetic, relative levels are a
creative decision when it comes to film and music.

I think I understand what you're trying to do in the field, i.e. lay
down a tone which allows you to align your playback volume later.
You can use a point source of broadband noise, but where to locate it
relative to the mics, and

Why not calibrate record levels in a controlled setting, using a
single speaker playing pink noise, mics equally spaced and angled
around it, note your levels, and duplicate your gain settings in the
field?  For instance, use an SPL meter to be sure each mic is
receiving 85dB of pink noise at the capsule, the set gain so your
recorder sees an average level of -20dBFS.

-jeremiah




--
-------------------------------------------------------------------
jeremiah lyman moore | sound+media | san francisco | 
http://babyjane.com/timeweb/
http://northstation.net/  downtempo acid jazz project


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