| The
best rooms ...
The best rooms are at least 15 feet wide, 20 feet
long and have a ceiling height of 8 feet or more. This allows the two
loudspeakers of a stereo system to be placed symmetrically and with their
tweeters at least 3 feet from side and rear walls. With the loudspeaker
tweeters 8 feet apart the sweet spot is located on the room symmetry line
and at 8 feet from left and right loudspeakers. This leaves more than 9
feet behind the listeners for the sound to travel before it is reflected
back. It is very important for balanced phantom image creation that the
immediate vicinity around the two loudspeakers is symmetrical.
Rooms can, of course, be much larger than 15 x 20
x 8 feet and with the loudspeakers much further than 3 feet from the
walls, but the optimum listening distance for phantom imaging remains
equal to the loudspeaker left-right separation or up to 1.5 times that
value.
Room construction can vary widely, which tends to
affect low frequency reproduction and sound transmission to and from the
neighbors. You take what you get and try to correct one or two frequencies
if necessary. But, if the room is pleasing to live in, to have a
conversation or to relax, is neither a dungeon nor a stuffed pillow, then
it is also suited for accurate sound playback. The room should be
furnished, have irregular hard surfaces, books and shelves for sound
diffusion, rugs, pillows and soft surfaces for sound absorption at higher
frequencies. Just keep it lively. The best loudspeakers will make you
forget the room, if the room talks back from all directions in the same
familiar voice.
Actually,
the loudspeaker is the problem
The room is usually considered to be the problem
when a loudspeaker does not sound right. Actually, the loudspeaker is the
problem, because it illuminates the room unevenly with sound at different
frequencies. The room merely talks back and the listener's brain cannot
withdraw attention from it. Room correction will make the loudspeaker
sound different but it cannot fix its off-axis frequency response, which
is heard via the room.
Below you will find a lot of theory that you can
safely ignore, because your room is most likely not one of those ideal
cases that can be described mathematically. No one can tell you the right
room proportions, though many have and are trying. Listening rooms in the
home are much more difficult to understand and describe than concert
halls, because their acoustic size varies from being small compared to a
56 foot wavelength at 20 Hz, to being very large at 10 kHz with 1.3 inch
wavelength. Concert halls are acoustically large even at the lowest
frequencies and thus easier to analyze and they have been studied
extensively. Even so, concert hall design is still a blend of art and
science. For your listening/living room design and layout follow the
simple guidelines above and forget what you read about 1/3rd rules, costly
room treatment products, magic wood blocks, etc. and use appropriate
loudspeakers.
Accurate
Stereo performance tests
SL - October
2009
|
