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Re: MS stereo imaging problems with MKH30/50 combo - Sounds are swap

Subject: Re: MS stereo imaging problems with MKH30/50 combo - Sounds are swap
From: "ajustend" ajustend
Date: Wed Oct 17, 2012 5:19 pm ((PDT))
That paper was VERY enlightening.

I love how it shows basically every combination of MS microphone ratio deco=
ded into the equivalent coincident (XY) format.

Again, very informative. Much appreciated!

-Justin

--- In  Michael Raphael <> wro=
te:
>
> This paper from Ron Stryker and Wes Dooley is worth a read:
>
> http://www.ribbonmics.com/pdf/technique.pdf
>
> If you are new to MS it should explain tons.
>
> Best,
> Michael
>
>
> On Oct 15, 2012, at 8:08 PM, ajustend <> wrote:
>
> >
> >
> > It definitely seems that the out of phase rear lobe of the MKH50 is wha=
t is causing my problem. The polar pattern of a standard cardioid seems to =
be much more ideal for what I am trying to accomplish, and since I am new t=
o MS recording I failed to realize how the rear lobe of the super-cardioid =
would end up translating.
> >
> > I figured that the rear lobe of the MKH50 Mid mic would only create a v=
olume bump in the sounds recorded directly behind (6 o'clock position) the =
Mid microphone. I did not consider the fact that when decoded the result wo=
uld be the same as a pair of super-cardioids in a coincident XY with both o=
f their rear lobes pointing across each other diagonally at the 4-5 o'clock=
 & 7-8 o'clock positions. :)
> >
> > Thank you for the feedback.
> >
> > -Justin Mullens
> >
> > --- In  "Avocet" <brini@> wrote:
> > >
> > > > 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.
> > >
> > > Justin,
> > >
> > > An excellent stereo test.
> > >
> > > > 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 comin=
g
> > > > from front left. And the exact opposite happens to the 7 & 8 o'cloc=
k
> > > > positions sounding like they are coming from the front right.
> > >
> > > That is what you would expect. M-S gives a good stereo image of a
> > > forward object, but at angles where M<S, the image tends to wander,
> > > then swap over. What you hear depends on your listening system.
> > >
> > > The best explantion for what is happening, especiually with an MKH-50
> > > / MKH-30 pair, is to look at the polar response diagrams side by side=
.
> > > As you look left and right, the M signal decreaes and the S signal
> > > increases. When they become equal (for a particular frequency) these
> > > are the full left and full right image positions.
> > >
> > > Beyond this "sweet image" the decoded M-S goes out of phase, and the
> > > image placement is not defined. I usually hear this as a behind image=
,
> > > but it may be just defocussed.
> > >
> > > The MKH-50 supercardoid gives a narrower front "sweet object" angle,
> > > but a larger out of phase rear object coverage. Now the MKH-50 has a
> > > rear lobe which is out of phase with the front lobe, so this swaps
> > > left and right when matrixed to L-R. As with the front image, an
> > > in-phase but reversed rear image can he heard as long as M>S.
> > >
> > > Increasing or decreasing the S signal moves the extreme L and extreme
> > > R object angles.
> > >
> > > Does this correspond with your walk around test?
> > >
> > > David
> > >
> > > David Brinicombe
> > > North Devon, UK
> > > Cogito cogito ergo cogito sum - Ambrose Bierce
> > >
> >
> >
>
>
>
>








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