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Re: Getting used to mics in the field

Subject: Re: Getting used to mics in the field
From: Walter Knapp <>
Date: Thu, 24 Apr 2003 21:46:28 -0400
Laloux, Dominique wrote:
> Walt said :
> 
> 
>>The samples I've put up show both some of the fumbling, 
>>and some of the variation. So far they are all close recordings, 
>>I'll try for some more distant stuff to put up
> 
> 
> Walt,
> 
 > This is another very basic question -- it will tell what my current 
level of expertise is --, but it relates to background traffic noise.
 >
 > What do you call "close recording". I know it is difficult to express 
it in yards or meters, as "close to" a very loud bird (or frog) is not 
the same as "close to" a more quiet bird or frog.

I generally mean 50' or less in talking about close recording. In the 
samples of frogcalls I put up this fits, except maybe the Brimley's 
Chorus frog where the near frogs were 20' and the far ones maybe 200'. 
As you noted, for any particular call you may be able to pick it up 
farther than a quiet call. But, the techniques and so on begin to differ 
beyond the shorter distance.

For avoiding traffic noise, I'd try for as close as the bird will 
tolerate. Keeping in mind that the call you are used to may depend on 
the echos and reverberation from the environment. If so it will sound 
thin if too close. More accurate, but thin, not like you are used to.

 > I often find that, even when I am relatively close to a bird (about 
0-15 meters), I have a reading between -40 and -18 db on the Portadisc 
(with the rec level at about 7). If I use a higher rec level (8 or 9), 
the background noise becomes really to evident. I then use the 
normalization feature of CoolEdit to push the track level to -6 or -2.

I normally record with the Portadisc's meter peaking at about -10dB if I 
can get that. There is a peak hold function in the Portadisc, and I 
normally have it on the 2second setting so as to hold the peaks for me 
to check. Best recordings seem to come from a range of about 5-7 on the 
Portadisc's settings. Those two factors are not independent, however.

When you go into the higher gain settings on the portadisc, you will 
begin to pick up a noise floor, which is a bit more likely to be mic, 
but at the top may include some from the portadisc. For me it varies 
more with which mic I have connected. I try to find ways to avoid using 
the top of the gain control.

Note that backing off on the gain to avoid noise, then normalizing later 
will not avoid noise. Better to get the call well to start with.

> What am I doing wrong ?

I'm not sure what you mean here. Sounds reasonable enough. Some would 
probably quibble about using normalization, but I only worry about that 
sort of thing when putting together a output CD so that sound levels 
reflect somewhat the originals.

Using a shotgun mic (or parabolic) it's very important to monitor the 
signal with headphones. Aim is fairly critical, more so for the 
parabolic than the shotgun. I'd really think a close bird would give a 
little higher readings. If your aim is off slightly that would drop the 
reading.

Did you see a change going from the ME shotgun to the MKH 416 in the 
readings you get vs gain settings? I'd expect there would be some. 
Impedance and sensitivity both differ.

Walt




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