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Re: Self-noise / coloration

Subject: Re: Self-noise / coloration
From: Walter Knapp <>
Date: Sat, 21 Feb 2004 16:26:19 -0500
>  From: Rob Danielson <>

> 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.

One should do everything they can to stay in the "sweet spot" of the 
pre. It's definitely not at the high end in any pre I've listened to.

My definition of sweet spot does not include gain. It's the best sound 
quality overall.

> 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 generally find the noise getting the upper hand if there is any 
significant amount of sound to record. Only in the silence between the 
sounds.

> 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?

Actually, the most obtrusive noise goes all the way off the bottom end 
of the frequency scale. Though a lot of that is not self noise.

> 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.

Inside recording is often about not recording much of the resonance, 
deliberately limiting it's effects. Partially because it's often off 
harder surfaces and thus more harsh. Nature recording is more about 
recording well with all the resonance. Which is often off softer and 
more irregular surfaces.

"prejudice through equalization" is a good term to how some react to the 
realities of nature recording, trying to fit it in their box.

A lot of the experience factor in recording is growing a awareness of 
the paths the sound is using. And how to work with those.

The trick I'm doing in putting a mic way up high is actually one of 
simplifying the reflections. And, if with a directional mic of aiming 
the mic down so it does not pick up more distant stuff than I want.

Walt




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