Rotel RSP-980 Owner's Manual page 24

SURROUND SOUND PROCESSOR RSP-980
left and right speakers too close to the side walls or to close the
wall behind them. Read your speaker owners manual for place¬
ment advice as the manufacturer should know placement re¬
quirements better than anyone else.
If you're still uncertain, begin by using the "rule of thirds." De¬
cide which wall you're going to place the front speakers on and
divide that dimension by three. Place the main speakers at those
markers. On a twelve foot wall, for example, place the left
speaker 4' away from the left wall and the right speaker 8' from
the same wall.
This gives you rough placement only. You may have to move
each main speakers bit towards the nearest side wall in order to
integrate the center channel speaker effectively but you'll find
this out only when you actually play movie soundtracks and mu¬
sic as you "fine tune" the system after you've set everything up.
Ideally, all front speakers (including the center channel) should
be exactly the same distance from your main listening position.
Place them in a slight arc — not in a straight line across the
front of the room. You'll benefit from higher precision and better
integration between dialog and front stereo effects in the result¬
ing image.
If you're using a direct view monitor (a conventional TV) or a rear
projection set, you'll have to place the Center speaker either
above or below it. Remember to aim the center speaker so that it
points at your ears when you're in your favorite listening/viewing
location.
Two piece front projectors offer the most flexibility (and, many
would argue, the best picture). From a sonic viewpoint, a perfo¬
rated ("perf") screen is best. A perf screen contains thousands
of almost-microscopic holes per square foot. These holes let
sound through so you can place the center speaker directly be¬
hind the screen at the same height as the main left and right
speakers. This ideal placement maintains vertical coherence as
sounds pan across the front.
One drawback to a perf screens is that the holes don't reflect
light from the projector. Typically, a perf screen results in a 30%
brightness reduction compared to a non-perf screen. You'll have
to make the decision to use one or the other based on overall
room conditions and your viewing preferences.
Surround Speakers
There are few hard and fast rules for surround speaker place¬
ment. Some organizations, notably the THX division of Lucasfilm,
Ltd., contend that the surround speakers should be placed above
and to the sides of your listening/viewing position. Although they
present cogent arguments in support of this advice, other au¬
thorities argue that placement on the rear wall is equally effec¬
tive. Remember that the THX advice must be taken in context:
THX mandates surround speakers which radiate sound in a "di¬
polar" pattern that complements side wall placement. (See THX
literature for more details.)
Those who suggest rear wall placement are usually very com¬
fortable with direct radiating speakers that generate sound in
one primary direction. Your Rotel dealer will gladly explore differ¬
ent possibilities with you.
Subwoofers
Subwoofers, because they deal exclusively with very low fre¬
quencies, can be the most difficult speaker to place effectively.
You'll need to experiment a bit to determine the best place for
them.
Remember that the job of a subwoofer isn't just to produce
heart-stopping thuds and growls. A good, properly placed
subwoofer must integrate with the rest of your system to pro¬
duce a continuously smooth response. If you're suddenly
"aware" of a separate subwoofer as your system is playing,
something is wrongl
Rather than understanding everything about room "modes' and
"standing waves' (two topics particularly germane to accurate
low frequency reproduction), we suggest the following points as
you begin to place your subwoofer:
•
Putting the subwoofer close to a wall will give you more bass
than if you placed it farther from the wall. On the other hand, the
extra bass energy may not be evenly distributed and may sound
'muddy"or "lumpy."
• Putting the subwoofer in a corner will give you even more bass
but an equally greater chance for uneven response.
• Conversely, placing the subwoofer well away from corners and
walls will reduce overall bass levels. Do not assume, however,
that the residual bass energy will be evenly distributed.
Try the following trick. Place the subwoofer in your favorite lis¬
tening position with its driver or port as close to where your ears
would be as possible. Play a test tone CD ("warble tones" from
about 30 Hz to 100 Hz are best, sine waves are less desirable)
and walk around the room until you hear a lot of evenly distrib¬
uted bass information. You might have to get down and do a bit of
crawling closer to the floor to really accomplish this but it will be
worth iti In any case, it's much easier to walk (or crawl) around
the room yourself than to put the subwoofer in one position, lis¬
ten from your favorite spot, move the subwoofer to another posi¬
tion, listen again, move it..., listen ..., move it..., listen ...,
etc.
What do you listen for? The most important characteristic of
good subwoofer placement is that all test tones sound equally
loud. You simply don't want any wide variations. If the 70 Hz test
band sounds much louder than the 40 Hz band, or if the 80 Hz
band is much lower than the 100 Hz tone, something's wrong
with the placement. "Experiment" is the keyword.
Once you've identified the place in the room where you hear the
test tones most convincingly, simply put the subwoofer there.
You may have to fine tune the position a little bit but you've al¬
ready identified the most likely place for proper placement.