User manual

(4.0E) 4-1
4. System operation
4.1. Setting up/stacking the loudspeakers
To get the best out of any high quality loudspeaker system it must be
properly set up. Care and attention needs to be paid to the position of
loudspeaker cabinets relative to each other and also to how they are
angled and aimed towards the audience.
Vertical aiming
The aiming of the loudspeaker in the vertical plane is responsible for
the coverage all the way from the stage to the furthest listening point.
Both the height and vertical angle of the loudspeakers need careful
adjustment. The best way to set the height and angle of cabinets
independently to each other is to use a loudspeaker stand with the
cabinet fitted to a swivel bracket. The loudspeaker stand can be the
usual free standing type or a simple column stand fitted to the top of a
subwoofer cabinet - both types are illustrated in the d&b system
brochures.
The lower the loudspeaker height, then the greater the sound level
difference between the audience area at the front of the stage and the
area at the extreme range of the loudspeaker coverage. To give a
relatively even level distribution the loudspeakers need to be placed as
high as practicable.
In relatively confined spaces there is a risk of aiming too much energy
towards the rear wall and ceiling, increasing the reverberant
component in the room. In the worst case bad speaker aiming can
create an audible slap echo from the rear wall, slightly tilting the
loudspeaker cabinets down towards the audience can reduce this
problem.
Because it’s HF horn has a built-in 8° downward tilt, the E9 loudspeaker
is ideally suited to this type of application. Usually there is no need to
use a swivel bracket - the cabinet can be fixed straight on to a
loudspeaker stand.
Horizontal aiming
The design of the C and E-Series cabinets simplifies horizontal aiming.
The precisely angled rear side panels of the cabinets precisely define
the edges of a cabinet’s horizontal coverage. It is easy to gauge the
extent of the horizontal coverage by sighting along a line from the
surface of each rear side panel of the cabinet.
Arraying mid/high cabinets
With more than one loudspeaker source in a room, comb filter effects
can create coverage problems. Comb filtering creates an uneven
frequency response across an area which is reached by two or more
sources at similar levels but at slightly different path lengths
(interference between the signals).
Therefore arrays need to be constructed so that the coverage patterns
of the individual loudspeakers combine with minimal overlap. Placing
d&b C-Series cabinets with their rear angled side panels butted
together guarantees minimal dispersion pattern overlap and hence
minimal interference.