The traditional recording studio has its acoustic
package either built into or mounted directly on the surfaces of
the room, the walls, ceiling, floor and corners. Acoustic Sciences
is fairly well known for the TubeTrap, those cylindrical bass traps
that are found standing is the corners of the room and other half
and quarter round traps that are mounted onto the surfaces of the
room. In 1986 ASC began experimenting with something entirely different.
The results were positive and engaging. The system evolved through
the help and interest of many people and it is found alive and well
in many recording studios today.
The ATTACK Wall is the opposite of traditional room
acoustics. It creates an acoustic space that exists well within
the room, away from the surfaces. Instead of built in or surface
mounted acoustics, the ATTACK Wall is a free-standing acoustic package
that is set up well inside the room, away from the walls and corners.
It's name, "ATTACK" is an acronym that actually comes
from the concept of an All TubeTrap Acoustic Control Kit, although
the more aggressive connotation is not completely by accident.
All studio design follows certain basic
acoustic principles and so does the ATTACK Wall. We will look into
how it satisfies the requirement for promoting a strong and clean
direct signal, how it provides a reflection free zone and how it
generates a time delayed diffusive backfill. The ATTACK Wall satisfies
the LEDE principle in studio acoustic design for both stereo and
surround mixing environments.
Recording studios design is based on
the well known "LEDE" type principle. Here we see a sound
level in dB vs time in milliseconds sketch of the ETC or Energy
Time Curve that defines the LEDE type acoustic signature. It begins
with the engineer receiving a strong and clear direct signal. Next
is the Reflection Free Period that lasts about 25 milliseconds,
during which the engineer should not receive any reflected version
of the direct signal. Following this, there is to be a time delayed
diffusive backfill flushing back into the engineering position.
This back fill keeps the recording space alive and comfortable to
work in. Without it, one would be working in an anechoic space and
that is very exhausting, especially in those late night hours. All
recording studio acoustic packages should meet the LEDE type criteria,
whether the acoustics are built into the walls, mounted on the walls
or set out well into the room, whether the control room is used
for stereo or surround mixing.
The piano keyboard represents the musical
frequency range. We have middle "C" which separates the
musical bass from treble. Most of the sound in the treble range
travels along straight lines and is easily represented by ray tracing.
The sound in the bass range however expands in all directions equally.
Both types of wave front behavior have to be included in the analysis
and development of a recording studio. The TubeTrap is an acoustic
device, a cylinder, whose entire surface absorbs bass but whose
front half reflects treble, the back half absorbs treble. Because
of this unique property, the TubeTrap has become a particularly
useful device in shaping acoustics in rooms.
