Here is a link to the recording I made:
http://soundcloud.com/justinmullens/ms-test-mkh30-50-handsofclock
-Justin
--- In "J. Mullens" <> wrote:
>
> Hi, this is my first post to Nature Recordists.
>
> I have just added an MKH 30 to my collection in order to expand into MS
> recording and am experiencing very bad imaging (side swapping) with the
> setup when the sound source is located in certain places behind the
> microphone.
>
> To clarify, I am *not *trying to record a surround signal using a stereo
> mic setup, but I *am *interested in maintaining a correct left-right ster=
eo
> image. When I use an XY setup, or an XY mic like a BP4025, anything on th=
e
> left side of the mic (in front of it or behind) will playback out of the
> left speaker. Using the MKH30/50 combo this is not the case.
>
> Here is the test I conducted: Set the microphones up in the middle of an
> open field so that I can walk in a full circle around it. I start directl=
y
> in front of the M/S setup, about 15-20 feet away, and walk in a clockwise
> direction around mic calling out each position on the clock face. 12 is
> directly in front, 1, is to the right of that, 3 is directly to the right=
,
> 6 is directly behind, 9 is directly to the left side, etc.
>
> Here's the problem, when I get to the 4 & 5 o'clock postions (rear right
> side) the sound source swap sides and sounds like it is coming from front
> left. And the exact opposite happens to the 7 & 8 o'clock positions
> sounding like they are coming from the front right.
>
> Again, any source originating in the 180 degree arc in front of the setup
> performs beautifully and the stereo image is perfect. It only happens to
> sounds coming from behind the mics, and if a sound source is making a
> constant tone you can actually hear it jump diagonally across from one si=
de
> of the stereo field to the other as it enters these rear right & left are=
as.
>
>
> After asking around it has come to my attention that the closer your Mid
> mic is to a pressure-gradient mic (figure 8 polar pattern), the more of a
> rear lobe you have, and thus the more chance you have of that rear lobe
> picking up sound in the opposite channel. This definitely explains how, a=
nd
> why, I could be experiencing side swapping.
>
> Since I've never used an MS setup with a pure cardioid mic I am wondering
> if the same thing happens... For those using a Sennheiser 30/40 MS setup=
:
> does this happen? Do you have side swapping in the 4-5 o'clock and 7-8
> o'clock positions?
>
> Nature recording is, for me, one of the areas where a really accurate
> stereo image in a 360 degree circle around my recording location is
> critical. I am always pointing my mics at the source I am recording, but
> having sounds behind the mic appearing in opposite channel is just weird.
> How do the MS recordists on this forum deal with this?
>
> Thanks!
>
> -Justin
>
>
>
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