Avalon Acoustics Sentinel - Manual (Page 55)

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11 Listening Position
Just as loudspeaker positioning and room treatment can address the issues of
standing waves, flutter echo, reflections, and bass reinforcement, careful
attention to listening position is crucial to achieving accurate sound stage
placement, tonal balance, harmonic structure, focus, and image size. In
order to fully benefit from the Sentinel Active Reference System's outstanding
resolving potential, one must consider the three dimensional location of the
listening position in relation to the system and room.
Path Length Symmetry
In the previous chapter, it is recommended to maintain left/right symmetry in
the listening room to preserve a balanced acoustic "space." Similarly, if the
listening position is severely off to one side, there will be a significant
difference in the path length of sound emanating from the loudspeakers. The
resulting time differential will disturb the overall left/right balance and cause a
phase shift in the information coming from one channel relative to the other
channel. Depending on the frequencies involved, some sounds will arrive at
the listener's ear to some degree out of phase and cause cancellations or
drop-outs in the frequency spectrum. Therefore, it is important to maintain a
listening position that is reasonably symmetric to the room and centered
between the loudspeakers.
Time Alignment
The front planes of the Sentinel Active Reference System have been carefully
sculpted to establish accurate driver time alignment. In Figure 10.1, notice
that the acoustic centers of the drivers are situated so that the wave front
converges precisely at the listener's ear. In order to achieve this
convergence, it is recommended to place the listener in a comfortable chair
or sofa with the listener's ear about 110 cm above the floor and a minimum of
two, and preferably three meters or more from the system.