naturerecordists
[Top] [All Lists]

Self-noise / coloration.

Subject: Self-noise / coloration.
From: Klas Strandberg <>
Date: Wed, 18 Feb 2004 02:00:50 +0100
All:

I disagree a little with most reasoning about flat frequency response and
naturesound recording. Such recording is so very different from studio work.

In a studio you move walls, ask the musicians to play differently or,
simply, move the "flat" microphone somewhere else. If you have a mic with a
strange freq. response - the music will sound "ugly", no doupt.

But the most important factor behind the reasoning about "flat frequency
curve" comes from the "old days". When using an analog recorder, you needed
to keep two things under control: As much saturation of the tape as possible
(at all frequencies) and no peaks produced by the mic at certain
frequencies. If the microphone had a bent curve, (peaks) you either had to
sacrifice tape-noise headroom or risk distortion when the mic boosted a
certain frequency. The frequency curve had to match the equalization of the
recorder. 

Nowadays, you can set the recorder at even -20 db, still get sufficient
dynamics. No risk for tape distortion. If you have a strange microphone, it
won't cause other problems than that you need to filter a bit at replay.
That some microphones just "sound bad", that is another story. 

The only times I call for excellent mics in nature recording, is when a
beautiful ambience is involved in the stereo picture, or a "nice wind" or
"nice water". It is usually difficult to get it "nice" anyway, with the best
of mic's.


Preamp noise / mic noise:
There are several simple ways to find out, accuratelly enough:

As a reference you can use a radio with fm noise between stations. Put the
mic at an exact distance from the loudspeaker, set a certain recording level
(perhaps - 10 db of your MD, DAT) and make a 30 sec recording of the noise,
then switch the radio off and make a 1 min recording of the "silence", as
good as you can. It doesn't matter if there is a distant traffic rumble or
atmo on the recording.

Then do the same proceedure all over, - set the same recording level by
using the FM radio, but now with the test object connected, (preamp or other
mic)

Make a stereo file of the two recordings. Remove all frequencies below 500
Hz. Equalize the FM radio noise of one channel so that it resembles the
other channel as much as possible. (Perhaps you have a software frequency
analyser?)

NOTE: If you can't make the two recordings of FM noise "equal", you can't
use this method!!

Listen to the "silence" of each channel. This way you will not only hear the
db-output, but also the characteristics of the noise. Spend money on a
preamp or other mic if you hear a difference.

Consider though, that a "distant" rumble may "mask" noise. The two
recordings may not be too different. And you really have to concentrate on
the noise itself, unless there is a really big difference. Also consider,
that even if two mics (pres) may measure the same self-noise, one self-noise
may be more "scratchy" than the other, and more audible.

Wayne writes about coloration due to distance, ground reflections and
general acoustic conditions. This coloration is HUGE!!! 

Klas.


At 14:43 2004-02-17 -0800, you wrote:
>Wayne Brissette, you wrote:
>
>>All this recent talk about pre-amp noise and microphone noise has me
>>wondering about coloration in nature recording. Unless people are using
>>omni microphones (and recent posting suggest people are using hypers and
>>shotguns) then there will be some frequency bumps and drops. This in
>>addition to some of the preamps talked about leads me to believe that
>>there will be some alteration in the sound. As a very rank amateur in
>>this field (although I have done my time in a studio), I'm wondering if
>>this matters much or since most people are trying to capture a specific
>>species of animal this doesn't play that big of a role. Anyhow, I'm
>>curious how all this plays into this field.
>
>For me, frequency response is the same for nature recording as it is 
>for music recording: I want the recording system to be as flat as 
>possible.
>
>Once I've working with it in the studio, however, I may filter and 
>equalize the hell out of it to bring out what I need, or to make it 
>sound more natural! Like a photograph, a recording is an illusion of 
>reality, and what's right is what makes the illusion you want.
>
>-Dan Dugan
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg 
>Yahoo! Groups Links
>
>
>
> 
>
>
Telinga Microphones, Botarbo,
S-748 96 Tobo, Sweden.
Phone & fax int + 295 310 01
email: 
       



________________________________________________________________________
________________________________________________________________________

<Prev in Thread] Current Thread [Next in Thread>
Admin

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the naturerecordists mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU