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Re: Stereo from ME66s

Subject: Re: Stereo from ME66s
From: "Mitch Hill" wa1ykn
Date: Fri Jan 27, 2012 10:47 am ((PST))
On 1/27/2012 9:03 AM, Avocet wrote:
>> I hadn't realised there might be a problem with a non matched second
>> ME66. Is it simply a matter of tweaking the volume of one channel to
>> fix this, or is there more to it?
> Robin and Peter,
>
> I'm repeating myself but as the mics are pointing at different
> sources, matching is not important. The only shared source is dead
> central, when the responses of two ME66's will be fairly well matched
> anyway except perhaps for a slight difference in level. A matched pair
> will be matched for the axial images only.
>
> Off-axis the frequency responses are never given as they can be very
> non-linear, and unmatched anyway, but in practice this is not too
> noticeable and an axially matched pair would not help.
>
> I'll be bold enough to say that any directional mic and even some
> omnis have very variable frequency responses off-axis.
>
> <  Snip>

To support what David (Avocet) is saying, here is a Coyote recording
made using two ME66 and two NGK3 microphones in a four microphone
array.  This recording was made with a Tascam DR-680 and microphone
array was coupled to the recorder using ProCom 50 foot mic cables. The
recording was post processed using Audacity to remix the 4 channels to 2
track stereo for posting on my web site. What this link takes you to is
a copy of the original recording with no other post processing, it is
basically the individual channels 1 - 4 from the DR-680 file remixed to
2 channel with no other processing or filtering and includes frogs in a
frog pond approximately 200 yards in front of the mic array as well as
distant street traffic noise and sounds of an aircondioner on a school
building starting up at about 40 seconds. There is also calling sounds
of an osprey flying in the distance:

http://www.4shared.com/mp3/0fnDHE7I/CCCoyotes02a.html

The microphone array consists of a 12" square aluminum frame made of 4
pieces of 1" x 3/8" aluminum bar stock mounted on a large photographic
tripod with the center two mics being the ME-66 pair aimed at
aproximately a 30 degree angle either side of center. The second pair of
mics ia a pair of R0de NTG-3 which are comparable to the ME-66 pair in
performance and mounted at an angle of 60 degrees either side of center
and 6" behind the ME 66 pair on the side bars of the square frame.

Drawing of frame:
http://www.4shared.com/photo/JbilEYMH/MicArrayFrm01.html

Drawing of frame showing overlap of microphone -6db/v pattern:
http://www.4shared.com/photo/NjWzfXBl/6micarray.html

Note that this 2nd conceptual drawing shows an additional two ME-64
microphones used in a later setup with the above described four
microphones with two SD 302 preamp /mixers bussed together and connected
by stereo bus to a Marantz PMD661 recorder, the concept being to expand
coverage for a long range 360 degree area...  This concept also works
well...

The concept of this recorder microphone setup was to record the sounds
of the local Coyote pack and strays along two salt water coastal bays
and several wildlife areas around the village center. The array was set
up on the roof of a building about 1/2 mile behind the village and
bordering one of the wildlife areas. Most of the Coyote pack activity is
located about 1/2 mile distant to the right of center with stray coyotes
joining in from as much as a mile away to either side.

I'm quite pleased with the results and how well the ME-66 and NTG-3
microphones worked together and with the ME-64 microphones.

--
--
Mitch Hill

(Sent from HP DV6T)







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