User Manual

20
4 System Configuration
4.1 Recognizing Problem Rooms
StudioLive
™
AI-Series Loudspeaker
Owner’s Manual
4 System Conguration
StudioLive AI-series full-range loudspeakers are designed to reproduce an input
signal with extreme delity, maintaining near-at frequency and phase response
at all levels up to the threshold of clipping. However, the performance of any
loudspeaker will be inuenced by the acoustics of the space in which they operate.
Dicult room acoustics, combined with improper loudspeaker placement, can
interfere with achieving the delity of which your StudioLive AI-series loudspeakers
are capable. To help you get the most out of your system, this section has been
included to guide you around some of the pitfalls when conguring a PA system.
4.1 Recognizing Problem Rooms
In most live environments, the room is rarely designed to maximize the listening
experience. More often then not, money is spent on aesthetic appeal rather than
acoustic treatment. For large-scale tour productions, venues are often sports arenas
that have been designed to maximize crowd noise. Smaller music venues are often
chosen for location or architectural aesthetics, rather than music reproduction.
While an empty warehouse or old wine cellar might make a great environment
to hang out in, it’s necessary to recognize and correct what that space does to
the sound system in order to optimize the PA’s performance in the venue.
In general, the following physical features of a room
can aect a sound system’s performance:
• Room size
• Construction
• Reectivity
The size of the room directly impacts how well certain frequencies will be
reproduced. For example, if you measure a room diagonally, you will discover how
well that room will be able to sustain low frequencies. This may seem odd until you
think about the physical size of audio waves at various frequencies. For example, a
50 Hz wave is about 22.6 feet long. (To calculate how big an audio wave is, divide
the speed of sound—1,130 ft./second—by the frequency. For a 50 Hz wave,
1,130/50 = 22.6 ft.) So a room that is 45 feet on the diagonal is going to regenerate
low frequencies more eectively than a room that is 15 feet on the diagonal.
When a room’s width or length correlates directly to the size of a waveform at a
specic frequency, a standing wave can occur where the initial sound and the
reected sound begin to reinforce each other. Let’s say we have a long, narrow
room where the distance from one side to the other is 22.6 feet. When a 50 Hz
wave bounces o the wall, the reective wave travels right back along the same
path and bounces o the other wall and cycle repeats. In a room such as this, 50 Hz
reproduces very well—maybe too well. So any mix will have a heavier low end.
In addition, low-frequency waves are powerful enough to cause the walls, ceiling,
and even the oor to ex and move. This is called “diaphragmatic action,” and it
dissipates energy and strips away the low-end denition. So if you’re in an old
cotton mill, and the walls and oor are made of thick concrete that don’t vibrate
much, the bass response is going to be much more powerful than if you’ve set up
a show in an old warehouse where the walls are made of barge board and tin.