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Re: surround recording

Subject: Re: surround recording
From: Walter Knapp <>
Date: Wed, 30 Jun 2004 11:20:22 -0400
From: Dan Dugan <>

> Another way to avoid comb filtering would be to use a PZM on the ground...

If the ground was flat and even for a fair ways. This PZM technique is 
good inside where such conditions are the norm. But, outside, classic 
comb filtering is less of the problem than the many different 
reflections off the irregular ground surface or surrounding objects. All 
slightly different phase. That's what you are really trying to get away 
from.

You are also getting away from the greater attenuation of sound by all 
the ground objects. Getting a more direct shot at distant subjects. In 
the past I've measured considerable drop in sound levels right at the 
ground. So the PZM would have a very significant disadvantage laying on 
the ground. It will do better up high too.

Walt




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