Wisdom Audio Series S90i - Manual (Page 12)

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extremely long waves do not contribute meaningfully to the imaging that the
main speakers create.
However, this fact does not mean that the placement of the subwoofers has no
effect on the sound quality in the room. Far from it. The subwoofers are the
most likely to suffer from the response irregularities introduced by the room
itself, operating as they do below approximately 80 Hz in most systems.
Recent research into the behavior of rooms as a function of speaker placement
has concluded that — if you have the freedom to do so — there are significant
advantages to placing several smaller subwoofers around the room, rather than
relying on a single large woofer. Moreover, the optimum placement is usually
centered on each of the four walls, or deep in the corners of the room. If you
have the luxury of doing so, this simple placement strategy can reduce the size
of the room’s response irregularities from 20 decibels down to perhaps as little
as 6-8 decibels—a tremendous improvement.
Reducing the room’s inherent problems to this degree provides a huge advan-
tage. It allows the SC-1 System Controller to put its considerable abilities to work
on perfecting your system’s response, rather than on trying to perform major
corrective surgery.
Room Treatment Rectangular rooms have six reflecting surfaces (four walls, ceiling and floor)
that reflect sound to the listener, after various delays introduced by the indirect
routes the sound take on their way to the listener. These first reflections are par-
ticularly damaging to sound quality. Looking at the simplest case of stereo repro-
duction, you have a minimum of twelve first reflection points in your room that
deserve some attention.
Unfortunately, it is often difficult to do much about the ceiling and floor reflec-
tions, even though they are arguably the most destructive. (The minimization of
these reflections is one of the strongest arguments for the tall, line source loud-
speakers that Wisdom Audio builds.) This leaves you with eight “first reflections”
that you should consider minimizing somehow. These points are easily found by
having an assistant slide a small mirror along the four walls of the room, while
you sit at the listening position. Any place on the wall where you can see a re-
flection of any speaker is a first reflection point. Concentrate on the first reflec-
tions for the Left and Right speakers first.
If you can, arrange to apply either absorption or diffusion at these eight points
(don’t forget the wall behind you). Absorption can be as simple as heavy, insu-
lated drapes; diffusion can be provided by a well-stocked bookcase with books
of varied sizes. Alternatively, you can buy purpose-designed room treatments
(some sources listed under References, below).
The important things to remember are these: a good room should have a bal-
ance of absorption and diffusion; and if you are going to treat only a few areas
of the room, the first reflection points are the most important ones to treat.
Professional Acoustic Design Does this all sound too complicated? For good reason: it is complicated.
The difference between the average listening room and one that is professionally
designed and implemented is huge. A great listening room will disappear to an
astonishing degree, letting the experiences captured in your recordings speak to