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Room Acoustics 13
the frequencies generated by your system. Much like an
instrument, they will vibrate and “carry on” in syncopation
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.
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 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 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 mat-
ter of fact, some rooms can be so “over damped” with
carpeting, drapes and sound absorbers that the music
system can sound dull and lifeless. 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 gremlins and diffuse any dominant frequencies.
Solid Coupling
Your loudspeaker system generates frequency vibrations or
waves into the room. This is how it creates sound. These
vibrations vary from 20 per second to 20,000 per sec-
ond. If your speaker system is not securely planted on the
floor or solid surface, it can shake as it produces sound
and, consequently, the sound can be compromised. If
your speaker is sitting on the carpet and only foot gliders
are used, the bass can be ill defined and even boomy. The
use of spikes is recommended to insure secured footing for
your speakers. (See ‘Solid Footing’ for spike information
and installation instructions).
Dipolar Speakers and Your Room
MartinLogan electrostatic loudspeakers are known as
dipolar radiators. 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 informa-
tion produced by the front of the speaker.
The low frequencies can either be enhanced or nulled
by the position from the front wall. Your Summit X’s
have been designed to be placed two to three feet from
the front wall (the wall in front of the listening position)
to obtain the best results; however, your room may see
things differently. So listening to the difference of the bass
response as a result of the changes in distance from the
front wall can allow you to get the best combination of
depth of bass and tonal balance.
Now that you know about reflective surfaces and reso-
nant 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 informa-
tion as it arrives at your ears later in time, can result in
confusion of the precious timing 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 negative
conditions occur.
Solid Footing
After living and experimenting with your Summit X’s, you
may want to use ETC (energy transfer coupler) spikes sup-
plied with the Summit X (see figure 5). With the use of
these spikes, the Summit X will become more firmly plant-
ed on the floor and, consequently, bass will tighten and
imaging will become more coherent and detailed. It is
best not to implement the spikes, however, until you are
secure in the positioning, as the spikes can damage the
floor if the speaker is moved. The feet that attach to the
bottom of the Summit X use a common
3
/8 - 16 thread.