> 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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