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While one can (and should) add acoustical treatment to large spaces, these are only effective to a certain degree
and not at really low frequencies. To effectively damp the reflection of a 350Hz tone the layer of damping
material applied to the wall would have to be at least 25cm thick! Instead of damping the reverbrations, using
speakers that exhibit a significant increase in directivity at all frequencies over traditional systems attains an
equal or greater improvement.
Thus the larger the room the more closely must the speaker control directivity to retain the same ratio between
the actual recorded sound and that produced by the room reverberation at any given frequency.
The AMR OptiArray® system provides a speaker system that can be expanded from a single pair, which is
appropriate in terms of directivity and acoustic output for rooms up to around 35m
2
(with normal ceiling height),
via a dual pair system that covers up to 70m
2
and scales through intermediate configurations of four and eight
pairs of speakers finally up to sixteen pairs in a 'focused dual line array' configuration, used to cover cavernous
listening spaces of up to 480m
2
*.
Due to the carefully considered directional properties of the single LS-77 and its seamless integration into larger
arrays. Each larger size array extends the tight (40
o
) vertical and wide but controlled (120
o
) horizontal radiation
angle to lower frequencies, counteracting the room’s tendency to have increasing reverb times at a given low
frequency with increasing room size.
A 2m tall vertical array of eight LS-77s manages to control the sound radiation down to 80Hz, whereas a single
LS-77 provides controlled directivity only down to 360Hz (which is still much lower a frequency than most high
fidelity speakers manage and entirely appropriate for moderate sized rooms).
*
Note - A room of 480m
2
is a small concert hall around 28m long and 17m wide!
The modular nature of the LS-77 OptiArray® system allows AMR’s setup to be scaled to almost any size
listening room. As the numbers of speaker pairs are increased in the Opti-Array configuration, the power
handling and SPL capability increase ever more dramatically over a single pair of LS-77s.