Hi Justin,
It is interesting, in the many times super-cardiod has been mentioned on th=
is group as a possible option in an MS setup, the expected convolution of t=
he stereo image has not really been explored until now.
In your localization test, I heard something similar to what Jos=E9 describ=
ed - though for the sake of interpreting the effect I will assume a theoret=
ical L/R symmetry for this array configuration.
The frontal stereo image becomes expanded, and the maximum perceived width =
occurs somewhere between 10 and 2 o'clock. At 11 to 1 o'clock the image see=
ms stretched from 60 degrees on location to around 90 degrees in playback. =
In this frontal wedge, the relative side to side localization of subjects m=
ight be fairly accurate. Though I think it is like stretching a rubber band=
: as the width is expanded the depth becomes thinned. To the sides and ba=
ck, including 10 and 2 o'clock and beyond the image becomes severely twiste=
d.
All arrays distort the image in one way or another, so I am not discounting=
super-cardiod MS as useful technique for stereo nature recording - though =
be extra careful with any content outside the angle of focus.
John Hartog
rockscallop.org
--- In "freitojos" <> wr=
ote:
>
>
> In my stereo speakers in a equilateral triangle 2mts 90=BA speakers. 12 =
was 0=BA in front, 1 was 45=BA my right 2 35=BA right, 3 20=BA right 4 10=
=BA right 5 10=BA left 6 was as 2 but far away 7 was 20=BA left 8 was 25=BA=
left 9 30=BA left 10 45=BA left and 11 12 0=BA in front.
> I hope this helps,
> Jos=E9
>
> --- In "ajustend" <ajustend@> wrote:
> >
> >
> >
> >
> > Here is a link to the recording I made:
> >
> > http://soundcloud.com/justinmullens/ms-test-mkh30-50-handsofclock
> >
> > -Justin
> >
> > --- In "J. Mullens" <ajustend@> 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 t=
he
> > > 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 ste=
reo
> > > mic setup, but I *am *interested in maintaining a correct left-right =
stereo
> > > image. When I use an XY setup, or an XY mic like a BP4025, anything o=
n the
> > > 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 dir=
ectly
> > > in front of the M/S setup, about 15-20 feet away, and walk in a clock=
wise
> > > 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 r=
ight,
> > > 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 ri=
ght
> > > side) the sound source swap sides and sounds like it is coming from f=
ront
> > > 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 s=
etup
> > > 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 on=
e side
> > > of the stereo field to the other as it enters these rear right & left=
areas.
> > >
> > >
> > > 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 lo=
be
> > > picking up sound in the opposite channel. This definitely explains ho=
w, and
> > > why, I could be experiencing side swapping.
> > >
> > > Since I've never used an MS setup with a pure cardioid mic I am wonde=
ring
> > > if the same thing happens... For those using a Sennheiser 30/40 MS s=
etup:
> > > 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 we=
ird.
> > > How do the MS recordists on this forum deal with this?
> > >
> > > Thanks!
> > >
> > > -Justin
> > >
> > >
> > >
> >
>
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