It definitely seems that the out of phase rear lobe of the MKH50 is what is=
causing my problem. The polar pattern of a standard cardioid seems to be m=
uch more ideal for what I am trying to accomplish, and since I am new to MS=
recording I failed to realize how the rear lobe of the super-cardioid woul=
d end up translating.
I figured that the rear lobe of the MKH50 Mid mic would only create a volum=
e 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 would =
be the same as a pair of super-cardioids in a coincident XY with both of th=
eir 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" <> 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 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.
>
> 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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