Here is an extract of BL50 technical guide (available on the B&O website):
Appendix 1: Recommendations for Critical Listening
14.1 Loudspeaker Configuration
The Beolab 50 provides you with an
extremely wide range of parameters
that can be used to adjust the timbral
and spatial presentation of your
recordings for various listening rooms,
loudspeaker placements and listening
positions. However, it is always best to
start with an optimal configuration in
your listening room.
First consider the relationship between
the loudspeakers and the listening
position itself. The two loudspeakers
and the listening position should be the
three corners of an equilateral triangle.
This means that the distance from
each loudspeaker to the listening
position should be the same as the
distance between each loudspeaker.
This also means that the loudspeakers
will be 30◦ away from the front, centre
location, directly in front of the
listening position.
Figure 14.1: The centre of the sound
beam in the vertical plane is level with
the top edge of the acoustic lens when
raised (at a height of 108.7 cm from the
floor).
Secondly, the two loudspeakers should
be “toed-in” by 30◦. This means that
they should be slightly rotated so that
they are both facing the listening
position. This is shown in Figure 14.2.
Figure 14.2: A “perfect” loudspeaker
configuration with Beolab 50’s. Both
loudspeakers are aimed at the listening
position. The distance from the listening position to each loudspeaker is the
same as the distance between the two
loudspeakers.
If possible, the height of the listening
chair should be set so that the
listener’s ears are level with the centre
of the vertical beam, shown in Figure
14.1.
The next consideration is symmetry
within your listening room. It is
commonly recognised that the best
stereo imaging will be achieved if the
listening configuration (the triangle
formed with the listener and the two
loudspeakers) is placed in left–right
centre of the room. Therefore, the side
walls will both be the same distance
from the listening position, and the
loudspeakers will have the same
distance to its adjacent walls. This is to
say that the distance from the left
loudspeaker to the left wall is the same
as the distance between the right
loudspeaker and the right wall. The
distance to the front wall (behind the
loudspeakers) should be the same for
both loudspeakers, but certainly does
not have to be the same as the
distance to the side walls.
Figure 14.3: An optimal placement for
the loudspeakers with respect to adjacent walls. Note that the distance between each loudspeaker and its closest side wall are identical, and that the
distances from the loudspeakers to the
front wall are also matched.
Figure 14.4: An less-optimal placement
for the loudspeakers with respect to adjacent walls. Note that the distances
from the loudspeakers to the front wall
are matched , however, the distance between each loudspeaker and its closest
side wall are not identical.
Figure 14.5: Another example of a lessoptimal placement for the loudspeakers with respect to adjacent walls. The
distances from the loudspeakers to the
front wall are matched, however, the
right loudspeaker and lacks a side wall
nearby.
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