At 2:41 PM -0600 4/15/06, Bruce Wilson wrote:
>I've got a couple Rode NT2000 mics. They work great in ORTF configuration
>(11 o'clock pattern setting), but when I try the mid-side configuration I
>can't get a stable stereo image, and there are holes in the pattern at
>different frequencies.
Hi Bruce--
You should be able to obtain some beautiful M-S derived stereo
imaging with the NT2000's. Did you experiment with an omni mid or
some of the "tween" positions between omni and cardioid?. Large
diaphragm cardioid mics can be "high-frequency centric," (brighter
in the center) but the cardioid polar pattern on the NT2000 shows off
axis response very comparable to small diaphragm mics. Perhaps try
switching back and forth between omni and cardioid positions on your
NT2000 mid. If the omni setting exhibits less frequency focusing,
then try using a tween position.
>I tried the cardioid mid with the mic standing vertically, and the
>figure-eight side with that mic placed directly behind the mid in a
>horizontal orientation. Very poor image that actually jumped back and fort=
h
>in the phones as I whistled and moved from 0 to 90 degrees. I guess it's
>path-length cancellation effects.
>
>
>Should the side mic be directly above the mid mike, and if so, how does on=
e
>do that with a stereo bar and the spider mounts that come with studio mics=
?
>Anyone do MS with studio mics in the field?
I use large diaphragm mics in M-S in vertical and front/back
configurations. Vertical alignment should provide more timing
accuracy for sounds in the (usually horizontal) plane perpendicular
to the mics but front and back positioning (like you tried) doesn't
seem to compromise timing enough for me to hear it. You can test this
yourself using very slight sample delay on a sound coming from dead
on. If I'm reading the specs correctly, the NT2000 is a dual
diaphragm mic. In the figure 8 pattern, it accesses discrete signals
from two capsules like the mkh-80/800.
I'm not sure I'd rely on the built-in decoder in making judgements,
even in the 722. I'd saturate both channels in the field (not encode)
and do simple "mixer style" decoding judging the result over
speakers. You might also want to pay attention to depth as well as
direction.
If you set up the ORTF & M-S tests to play back to back, that could
be very telling.
>I also tried a near-coincident Blumfield (two figure 8's @ 90 degrees and =
a
>head-width apart) but the center image was weak and phasey.
For stereo end-products, it seems that what is common to both of the
mics in the "front" and to the "rear" gets mixed into one "middle".
For me, Blumlein works nicely for close sources surrounding the mics,
but the imaging gets more and more undefined for sources in the
distance.
>
>
>Bruce Wilson KF7K
>http://science.uvsc.edu/wilson
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