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Re: parabolic mics + recorder noise

Subject: Re: parabolic mics + recorder noise
From: "Raimund" animalsounds
Date: Thu Jun 9, 2011 1:47 pm ((PDT))
< With my LS-10, I discovered that even though I got a lower recorded level=
 than I wanted with LOW and 10, when that signal was digitally raised in po=
st it was still quieter than HIGH and a lower setting producing the same mo=
dulation. >

Yep, I now remember that we already discussed this issue a few years ago. A=
t that time I also measured the noise levels both at LOW and 10 (-113dBu) a=
nd at HIGH and 2 (-103dBu) because these two settings provide both the same=
 clipping level of -30dBu (see T=
he explanation for this behavior is obvious:

The recording level dial is a simple potentiometer (attenuator) that is pro=
bably located more or less at the input of the recorder and the LOW/HIGH sw=
itch adjusts the gain of the preamplifier that is located between that pote=
ntiometer and the A/D converter. It is therefore not a good idea to first a=
ttenuate the signal (by turning down the record level dial to position 2) a=
nd afterwards amplify it again. The intermediate low signal level will then=
 degrade the overall signal-to-noise ratio. For the same reason it is for i=
nstance not recommended to activate the 10 dB pad on a microphone and at th=
e same time rise the gain of the recorder to compensate this attenuation.


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