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Re: Infrasound microphone

Subject: Re: Infrasound microphone
From: "James Shatto" wwwshadow7
Date: Wed Jul 28, 2010 8:24 am ((PDT))
Heh.=C2=A0 I got the MM-1's to IMPROVE the low end.=C2=A0 And they do just =
that relative to the preamps on my Korg MR-1000.=C2=A0 My Avenson STO-2's a=
re still a little light in the low end in general, plus high in the noise f=
loor.=C2=A0 I also got the MM-1's to improve battery life by moving the pha=
ntom power burden off the field recorder.=C2=A0 And they do just that.=C2=
=A0 2.5 hours on fully and freshly charged NiMH batts for the Korg by itsel=
f.=C2=A0 2 hours or less if the batts were charged a week ago and left in t=
he off field recorder.=C2=A0 With the MM-1's, in addition to the Korg, I've=
 done 4 hours continuous and the field recorder still showed 50% on the met=
er.=C2=A0 Which takes about 30 minutes to go past with just the field recor=
der and phantom powered STO-2's.

EQ is your friend.=C2=A0 Not really doable at those frequencies live though=
.=C2=A0 Baring some DIY and other custom electronics.=C2=A0 You also need a=
 monitoring environment capable of producing those tones to hear what you r=
ecorded.=C2=A0 Otherwise you might need to double the speed or more to brin=
g those frequencies up to the reproducable range depending on your gear.=C2=
=A0 Audacity has some tools to analyze and filter and EQ.=C2=A0

Even if your headphones are spec'd to 5Hz, they probably don't actually pro=
duce that.=C2=A0 And wind noise and other things can be in that range, so t=
here's not much proofness in such content.=C2=A0 Although using that range =
as a location detector might be interesting.=C2=A0 Those lower frequencies =
don't travel as well over distance in air.=C2=A0 Visions of indians with th=
eir ear to the ground come to mind.=C2=A0 I guess I should have done more s=
chool.=C2=A0 It's feasible to make a locator with three points in contact w=
ith the ground.=C2=A0 Strength and timing to each sensor (mic) to determine=
 a direction.=C2=A0 Much like earthquakes and the use of three points to de=
termine the epicenter.=C2=A0 I'm not sure how useful it'd be without hard d=
ata to single out the subject from deer, bear, squirrel, wolf, wildcat, moo=
se, and whatever other critters.=C2=A0 It's a noisy world out there.=C2=A0 =
And you'd only be able to detect when the subject was moving.=C2=A0 And try=
ing to find / catch up with a moving
 target might be an exercise in futility.

I've had SM81's that were decent on the low end.=C2=A0 No measurements thou=
gh.=C2=A0 Just a hankering for some Tuba.=C2=A0 An old AT4033a was pretty s=
weet on the low side.=C2=A0 A current AT3035 that is okay down low.=C2=A0 N=
oticeably better than my STO-2's.=C2=A0 None of which I'd want to use outdo=
ors since wind proofing them would be near impossible.=C2=A0 Plus you need =
some decent shock mounts or it's all handling noise.=C2=A0 Special cables a=
nd other things to further isolate them from the rigging.=C2=A0 Good luck w=
ith that as that range is probably the most difficult to do well.=C2=A0 I'v=
e been longing for some MKH8020's which spec okay down there according to t=
he manufacturer anyway.=C2=A0 But not cheap, and not the most favored of th=
e not cheap mics.

- James


--- On Wed, 7/28/10, Eric Benjamin <> wrote:

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