At 12:35 2004-02-18 -0600, you wrote:
>At 2:00 AM +0100 2/18/04, Klas Strandberg wrote:
>>
>>
>>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 th=
e
>>mic at an exact distance from the loudspeaker, set a certain recording le=
vel
>>(perhaps - 10 db of your MD, DAT) and make a 30 sec recording of the nois=
e,
>>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 o=
r
>>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 ot=
her
>>mic)
>>
>>Make a stereo file of the two recordings. Remove all frequencies below 50=
0
>>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.
>
>Of course, I cranked the mic pre in my test with the specific
>interest of _recording the background_. One can also start off with
>max mic pre gain and lower it in steps listening for the "sweet spot"
>where the most gain with least addition of noise is realized.
>
>Using radio fizz to simulate local hi Hz sources like moving leaves,
>grass, running water, insects, radio fizz is clever, but doesn't the
>high end in many natural settings drop off so quickly that the noise
>from the mic/pre combination quickly rises above them? My specrtral
>curves outside are very steep.
I don't mean to simulate anything, just get a reference.
Klas.
>
>
>>Consider though, that a "distant" rumble may "mask" noise. The two
>>recordings may not be too different. And you really have to concentrate o=
n
>>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-no=
ise
>>may be more "scratchy" than the other, and more audible.
>
>As Walt and I discussed a while back, I find the most obtrusive noise
>contributed by mic/pre combinations is in the range of 125 to 900Hz.
>Lower signal to noise in this range places a sonic haze over the
>subtle reflections of the local acoustics/communications. Could this
>be a component of your "scratchy" description?
>
>>
>>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 an=
d
>>>>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
>>
>
>What is increasingly interesting to me about this process of partial
>"recovery" of mic/pre etc. prejudice through equalization is how
>much more aware of the influences of the physical surroundings I
>become-- like comb filtering along the ground, or the echo from a
>wall of trees surprisingly far away. The practice truly does require
>getting to understand the "real" better.
>
>It seems like my work is often to lessen the resonance(s) of a
>location so that the lower level phenomena may be audible. This is
>contrary to experience in the field, where local resonance is often
>the harbinger of overtones, edges and access to greater details.
>Rob D.
>--
>Rob Danielson
>Film Department
>University of Wisconsin-Milwaukee
>
>
>"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:
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