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Re: Machine Gun microphone

Subject: Re: Machine Gun microphone
From: "Greg Clark" greg_in_az
Date: Fri Sep 7, 2007 11:10 am ((PDT))
Well I guess I will weigh in on this topic. I built one of these in 1957
because shotgun mics and parabolas were not available at affordable prices
for my project. I was 10 yrs old at the time. I wanted to detect human
voices, not birds. I think it works pretty well for voice stuff and my
understanding is that in the 1950's, when I built one, this was one of the
few ways to go for mechanical amplification. I don't know when modern
shotgun mics were invented, but they would have been pretty pricy back then=
Getting a parabola during the same era would also have been expensive, if
you could find one at all. Parabolas were certainly around back then, but i=
it cost a few hundred dollars that was a fortune. A good car cost a few
hundred dollars. Today, there is no advantage for natural sound recording
because flat frequency response shotgun microphones allow quiet electronic
gain to be applied to the signal. A parabola has all kinds of non-linearity
compared to the microphone, but is considered a wonderful tool nevertheless=
The tube amplification will produce a whole series of holes in the frequenc=
response and will probably produce something so non-linear that the defects
could not be removed without a lot of work. I think this technology would b=
good to use as a historical comparison technology to show how far we have
come in the last 50 years and it would be interesting physics project for
the public to see in a sound museum. But for real recordings, its day has

Greg Clark

-----Original Message-----
 On Behalf Of Michael Oates
Sent: Friday, September 07, 2007 10:44 AM
Subject: Re: [Nature Recordists] Re: Machine Gun microphone

Hmmm, Not sure if I want to go ahead with this if I am going to get lots of
the spectrum
missed in the recording. The way I would build it, it would not be cheap. I=
I start to
add up all the extra bits apart from the tubes, =A3200 is a more likely
figure, so not
exactly cheap just to try! And it would take a few weeks to make.

I would like to hear from someone who had had some success with this type o=
especially if comb filter effects can be avoided. This could be the reason
why information
on this type of mic is hard to find and is widely being used.



>I have had one of these since the 1970s. Built it from plastic
>piping, and was never happy with the performance, but it does work.
>It was the original shotgun microphone for those with little money.
>Mine was originally built for a limited spectrum of sound with quite
>a few fewer tubes than the project you plan. They are a fun project
>if you want to try one. I'd be interested in how your project turns
>--- In  "Michael Oates" <>
>> Has anyone every made and used a machine gun microphone. There is
>> much about these on the internet, but I have found this:
>> I am concidering making one using 90 tubes of 8mm diameter
>> tube with lengths from 1m down to 9mm. (That is two more rings of
>> tubes than shown on the example making it 88mm diameter instead of
>> 67mm) I was thinking of fitting a Rode NT1A as the condenser mic.
>> I really want to know if anyone has tried such a beast. Based on
>> length of tubes I would use, it should work from about 150Hz to
>> range and appears to be very directional.
>> My idea of using more tubes that in the example it to fill in the
>> gaps in the frequency range, but I don't know if that's needed.
>> Cost would be about =A3120 for the tubes plus a bit more for for
>> fitting some windshield around it with fake fur on a wire frame
>> former covering the full length.
>> Thanks,
>> Mike

"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause

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