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Re: Re: Quick parabolic mic.

Subject: Re: Re: Quick parabolic mic.
From: Walter Knapp <>
Date: Wed, 23 Oct 2002 21:55:01 -0400
Shaun wrote:

> Hi Walt, 
>         Thank you for such a fast reply, i never even thought of the 
> chemicals in the sealer hurting the mic (Phew) But i have to say that 
> i'm not familiar withthe pink foam for computer parts you are talking 
> about. But about the wind screen, since you brought that up, would a 
> piece of foam (the kind off of a pair of earphone speakers be ok for 
> a makeshift windscreen, if not what would you consider from around 
> the house? And one other thing that i completly forgot to mention in 
> my first post. It was said to test the mic with pink noise? Sorry but 
> i have no idea about what this is , although i have cool edit pro, 
> and have seen "pink noise" or "add pink noise" in one of the drop 
> down menus of the program. I figure i can add pink noise to a new 
> blank session, how long (as in minutes/seconds) would  be appropiate 
> to test the mic, or mabye just loop it to fill the entire cd then 
> burn it in wave format?

When you get in some piece of electronics or some other things, it 
sometimes comes wrapped in sheets of thin foam to protect it. Consumer 
stereo gear almost always does, though theirs is thinner than what the 
computer people use. The same plastic foam can be found inside some 
mailing envelopes. It can also sometimes be bought at places like office 
depot or others selling mailing supplies. The pink stuff I've seen looks 
like the plastic may be polyethelyne.

Another thing that will work is just a couple styrofoam packing peanuts. 
Make sure it's the non-environmentally friendly kind that does not 
shrink away from moisture. The kind that won't degrade in a zillion years.

There is nothing magic about what's used. Helps a lot if it's immune to 
humidity, and does not transmit sound much and is a bit elastic so it 
will hang in there by simple compression. Except for the mold it might 
grow, a old piece of cloth rag might do.

Headphone foam cover material will work ok for a crude windscreen. It 
has to be a open foam to let the sound through, so not all foam you find 
around will work. If you are using the Telinga reflector, the best 
windscreen is some light fuzzy material stretched across the entire 
front of the reflector. That's what the official Rycote one for the 
Telinga is like. The small bit of foam direct on the mic also has the 
function of keeping dirt and such like from getting into the mic itself, 
so is worthwhile even if using the large windscreen.

I don't see a lot of need for testing like that. Pink noise is random 
sound covering the entire frequency scale, but who's energy is 
distributed logarithmically. As opposed to white noise where the energy 
is fully even through the entire spectrum. So pink noise emphasizes 
lower frequencies over higher and is considered a more "natural" random 
noise. Anyway, it corresponds, kind of, with the way we hear sound.

How much you would need would depend on what analysis you were going to 
do. Just playing and recording the noise does not tell a lot. And 
remember, your system of playing it has to be perfect for it to be just 
testing the mic. Otherwise you are testing the combination of your 
playing system and mic system. And at best you are finding out how it 
records pink noise. Real natural sounds are each different.

If you are into putting numbers on the mic's specifications it can be 
useful. But mostly if deciding between two or more mics. My own 
preference once I have a mic is to just get out and see what and how it 
will record of the natural subjects I'm interested in. Learn what it 
will do to get the optimum from it. If in the end the mic won't do what 
I want then I'll go back to mumbling over mic models and specifications 
again for my next try.

It's a hobby all unto itself to be endlessly testing things. Some people 
never seem to get around to recording, but test only. Since nothing's 
perfect it can also be a way to be constantly unhappy with your equipment.

Walt




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