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Re: Making a parabola

Subject: Re: Making a parabola
From: "Scott Fraser" scottbfraser
Date: Sat Sep 22, 2012 10:03 am ((PDT))
<<Scott, with modern recorders it has all got twisted and uncertain.
1/ Using a certain recorder model "A" - where, in the chain, is the
internal base filter? Will wind amplitude distort the input stage,
even if the base filter is used? We don't know that, and it seems to
vary with models.>>

I was making the assumption, probably unwarranted, that the high pass filte=
r is invoked prior to gain stages, as it is in professional gear. The proli=
feration of budget consumer devices has definitely muddied the waters when =
referring to professional recording procedures. The implementation of filte=
rs, pads, limiters, & even record gain setting in DSP (i.e. post AD convers=
ion) renders the rationale for using these processes in the first place com=
pletely meaningless.

<<2/ How does recording level interact with noise? We don't know that
either, and it varies with recorder models. The Olympus LS makes much
more noise at 16bit than on 24bit, for example, regardless of the
recording wheel setting. And noise figures vary a lot, depending on
sensitivity setting "low" or "high", regardless of the recording
level showing on the meter, but depending on the sample rate.

I think by trying to make a device foolproof for amateur users manufacturer=
s have made their products rather useless for people with enough experience=
 to know how to set proper record levels.
What's important to mention, regarding the question of high pass filtering =
when recording vs in post production, is that one cannot rely on high pass =
filtering alone to eliminate wind issues. Mechanical strategies, such as ze=
ppelins, furries, fuzzies, foam socks, etc. are necessary to prevent wind f=
rom directly hitting the mic's diaphragm at full velocity. Once a physical =
membrane is in place, the high pass filter can, if needed (& if in a pre-ga=
in place in the signal chain,) attenuate LF problems.

Scott Fraser

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