MartinLogan EFX Manuel De L'utilisateur page 24

r a
ooM CoustICs
Your Room
This is one of those areas that requires both a little background
to understand and some time and experimentation to obtain
the best performance from your system. Your room is actually
a component and an important part of your system. This com-
ponent is a very large variable and can dramatically add to, or
subtract from, a great musical experience.
All sound is composed of waves. Each note has its own wave
size, with the lower bass notes literally encompassing from 10'
feet to as much as 40' feet. Your room participates in this wave
experience like a three dimensional pool with waves reflecting
and becoming enhanced depending on the size of the room
and the types of surfaces in the room.
Remember, your system can literally generate all of the infor-
mation required to recreate a musical event in time, space, and
tonal balance. Ideally, your room should not contribute to that
information. However, every room contributes to the sound to
some degree. Fortunately MartinLogan had designed the EFX to
minimize these anomalies
Terminology
Standing Waves
The parallel walls in your room will reinforce certain notes to
the point that they will sound louder than the rest of the audio
spectrum and cause "one note bass", "boomy bass" or "bloated
bass" . For instance, 100Hz represents a 10 feet wavelength. Your
room will reinforce that specific frequency if one of the dominant
dimensions is 10 feet. Large objects in the room such as cabinetry
or furniture can help to minimize this potential problem. Some
serious "audiophiles" will literally build a special room with no
parallel walls just to help eliminate this phenomenon.
Reflective Surfaces (near-field reflections)
The hard surfaces of your room, particularly if close to your
speaker system, will reflect some waves back into the room over
and over again, confusing the clarity and imaging of your system.
The smaller sound waves are mostly affected here, and occur in
the mid and high frequencies. This is where voice and frequen-
cies as high as the cymbals occur.
Resonant Surfaces and Objects
All of the surfaces and objects in your room are subject to
the frequencies generated by your system. Much like an
instrument, they will vibrate and "carry on" in syncopa-
tion with the music, and contribute in a negative way to the
music. Ringing, boominess, and even brightness can occur
simply because they are "singing along" with your music.
24 Room Acoustics
Resonant Cavities
Small alcoves or closet type areas in your room can be chambers
that create their own "standing waves" and can drum their own
"one note" sounds.
Clap your hands. Can you hear an instant echo respond back?
You have near-field reflections. Stomp your foot on the floor.
Can you hear a "boom"? You have standing waves or large panel
resonances such as a poorly supported wall. Put your head in
a small cavity area and talk loudly. Can you hear a booming?
You've just experienced a cavity resonance.
Rules of Thumb
Hard vs. Soft Surfaces
If the front or back wall of your listening room is soft, it might
benefit you to have a hard or reflective wall in opposition. The
ceiling and floor should follow the same basic guideline as well.
However, the side walls should be roughly the same in order to
deliver a focused image.
This rule suggests that a little reflection is good. As a matter of fact,
some rooms can be so "over damped" with carpeting, drapes and
sound absorbers that the music system can sound dull and life-
less. On the other hand, rooms can be so hard that the system can
sound like a gymnasium with too much reflection and brightness.
The point is that balance is the optimum environment.
Breakup Objects
Objects with complex shapes, such as bookshelves, cabinetry
and multiple shaped walls can help break up those sonic grem-
lins and diffuse any dominant frequencies.
Dipolar Speakers and Your Room
MartinLogan electrostatic loudspeakers are known as dipolar radi-
ators. This means that they produce sound from both their fronts
and their backs. Consequently, musical information is reflected by
the wall behind them and may arrive, either in or out of step, with
the information produced by the front of the speaker.
Now that you know about reflective surfaces and resonant
objects, you can see how the midrange and high frequencies
can be affected. The timing of the initial wave as it radiates to
your ears, and then the reflected information as it arrives at your
ears later in time, can result in confusion of the precious tim-
ing information that carries the clues to imaging. Consequently
the result is blurred imaging and excessive brightness. Soft walls,
curtains, wall hangings, or sound dampeners (your dealer can
give you good information here) can be effective if these nega-
tive conditions occur.