SCHOEPS UMS 20 - Handbuch (Seite 15)

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M/S Stereo
15
English
Fig. 10 M/S with cardioid and figure-8, shown for the left channel
ϕ = acceptance angle; (this is greater than the pickup angle in this case.
Only when this is exceeded will reproduction errors arise.)
ω = angle between the two “virtual microphones”
ω = 0°
ω/2 ω/2
ω/2
ϕ/2
ϕ/2
ϕ = 0° *
ϕ = 180°
Mono
S = 0%
M = 100% (unusable)
S = 100%
M = 0%
main stereo axis
increasing ratio of S signal to M signal
A short distance will sound ”dry” while
microphones placed at a large distance will
record ”more room.” The latter is usually
desired if the room has nice acoustics.
What this all implies is that it is best to
choose the distance primarily for aesthetic
purposes, where the acoustic properties of the
room are as important as anything else.
3. and 4.
In order to determine the angle
ω and the
dis tance d between the microphones, you
first have to determine the pickup angle
α.
You can do this with the help of Table 1 on
page 5. T he pickup angle
α is calculated
from the ratio of the s ound s ource width b to
the distance a from the sound source (Fig. 9a).
In such a case, a and b have to be either esti-
mated, paced out or measured.
You then look for the curve in Figure 9b
that comes closest to the pickup angle calcu-
lated in the manner just described. Along this
curve lie all possible settings for d and
ω that
give the best reproduction of the stereophonic
recording angle within the playback area.
M/S Stereo
...with axially addressed microphones
(blue markings; Fig. 3)
Microphones:
For the mid signal: typically an MK 4 cardioid
or MK 41 supercardioid, or possibly an omni-
directional (MK 2S or MK 3);
for the side signal: an MK 8 capsule
(or MK 6 in figure-8 position).
Angle the clamps so that they point verti-
cally out from the rail. Now insert the micro-
phones. The clamps should grip the micro-
phones as close as possible to the plug end.
Now, first angle one of the clamps down as
far as it goes towards the middle of the rail,
then angle the other clamp until it is touching
the first. Make sure the plug ends of the two
microphones are flush with each other. Then
the capsules will also be correctly positioned.
Now you need to align the pickup axis of the
side microphone (figure-8). This is correct
when the red dot on the microphone is facing
the left side of the sound source.
More information on MS with cardioids
and figure-8 is given in Fig. 10.