Fascinating MS
"Gary Eickmeier" skrev i en meddelelse
...
A possible new problem has come up with MS, namely some imaging
anomalies at different frequencies.
Yes and no, ie. I trust them to be there and they are not a result of MS, MS
and XY remains mathematically equivalent. There is then the issue of stereo
acceptance angle, ie. the room segment that is placed between L and R, see
also the paper "The Stereophonic Zoom".
When I do my stereo test and even during a performance, I have noticed
that higher frequency percussive sounds will image in the center more than
at left or right. Like, the drum set is at stage left, but there are some
pings and other sounds that come from the center.
Is this some well known principle, or fault, of MS? Ever heard of it?
You are using large membrane microphones AND you tell us you evaluate stereo
played back as 5.1. All bets are off for both reasons, the most likely cause
is however large membrane anomalies.
To evaluate mic off axis behaviour:
set up recorder to record one channel
connect one microphone to recorder
set recorder to record
hold microphone in a straight arm in front of you
be on axis
recite Mary had a little lamb, entire poem
rotate microphone so that you are 45 degrees off axis
recite Mary had a little lamb, entire poem
rotate microphone so that you are 90 degrees off axis
recite Mary had a little lamb, entire poem
rotate microphone so that you are 135 degrees off axis
recite Mary had a little lamb, entire poem
rotate microphone so that you are 180 degrees off axis
recite Mary had a little lamb, entire poem
Listen to recording and evaluate, fft analysis may or may not be
informative.
If you are really bored repeat with the other three microphones, they will
probably be somewhat different.
The expected difference is that any treble "issues" will be more prominent
off axis if correlated with resonance in the housing, but you'll be the
first to know. Consider one microphone aimed at the drumkit and linear on
axis and one microphone aimed 90 degrees away from the drumkit BUT "almost
omni"" from 7200 to 8800 Hz because of a resonance and it gets obvious why
the intensity information will cause the highhat to move towards center.
Speak at one meter, even if only on axis, is a very good fast way to compare
microphones and select the best sounding. It was such a test that made me
skip buying calrec condensers in the early 1980'ties, however I also didn't
really have very much use for them then, if I had really needed them I had
asked for some more to compare and selected the two best.
Gary
Kind regards
Peter Larsen
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