A conventional recording studio design is called
a LEDE type studio, LiveEnd DeadEnd. Although the original LEDE
type studio concept was a study in pure geometry, a room shape that
gave no early reflections, one that did not use absorptive or diffusive
devices. This oddity quickly gave way to a more conventional way
of setting up a studio in a rectangular room. The front half of
the room was made acoustically dead and the back end of the studio
was made acoustically diffusive or live. As long as the distance
to the back wall was about 12 feet, the requirement of a LEDE room
was met. However, these rooms had the clear distinction of one end
being dead and one end being live, hence the acronym LEDE. But when
it comes to surround audio, there is no "End". What is
the DeadEnd for one speaker becomes the LiveEnd for another speaker.
5.1 Studio design seems to not be able to meet the LEDE requirement,
at least using conventional design practice.
The baffles used in the ATTACK Wall are double sided.
The front faces the mix position and is full bandwidth absorptive.
The backside faces the bare walls of the room and is very diffusive.
Each set of baffles is open at the bottom and top. Sound that hits
the ceiling bounces over the baffles and sound that hits the floor
bounces under the baffles. These rays hit the wall behind and are
reflected onto the diffusive backside of the baffles. At this point
the sound has been sufficiently delayed and diffused. It is scattered
back again towards the bare wall where it is finally reflected back
over and under the baffle wall and into the engineering location.
Vertical Circulation Paths
In addition to the over and under
action by the vents above and below the baffles, there are also
lateral vents in the overall 5.1 ATTACK Wall setup. By ray tracing
sound from each speaker that exits through each vent and on through
a sequence of wall reflections, a lateral condition of diffusive
backfill is created. The space between the reflective side of
the baffle system and the bare walls works well when kept in the
3 to 6 foot range. Larger rooms retain the reflection free condition
but the onset of the diffusive backfill becomes more time delayed
and weaker in level.
Lateral Circulation Paths
By using properly designed and
positioned acoustic baffles, essentially gobos, the three stages
of proper recording studio design can be met. The strong and
undistorted direct signal is launched from the speaker array.
The sequence of early reflections that distort musicality and
imaging are eliminated and a backfill of time delayed diffusive
energy is returned to the mix environment. The most interesting
aspect of this is that not only the speakers are in a surround
configuration but the diffusive backfill is also delivered to
the engineer in a surround format. The old fashioned LiveEnd
DeadEnd style of studio design cannot produce a surround mixing
environment. In this new medium the ETC definition for studio
design remains the same but its spatial or geometric representation
is forever changed. The new design criteria is identified by
the acronym LSDS ™, LiveSurround DeadSurround ™.
Typical "LSDS"™ Type ETC Signature
The original reflection free
zone first conceived by Chip Davis was a geometric space that
was reflective but sized and shaped to avoid reflections during
the first 25 milliseconds following the direct signal. Nobody
really built these rooms but the idea spawned two decades
of one-dimensional LiveEnd DeadEnd studio designs. Now, studio
design has come full circle due to the seemingly insurmountable
mutually exclusive requirements of surround studio speaker
positions. What started as a geometric surround studio design
concept has become an acoustic surround studio design reality.
Although it took TubeTraps to pioneer the concept, it will
be up to the professional studio designers to adopt this next
wave in studio design, the LSDS ™ type studio.
